Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

水道原水である河川水が降雨に伴い濁りが増すと、浄水場での最適PAC注入濃度も多くなることはよく知られたことである。しかしながら、大分県杵築市浄水場では、無水降水期間に水道原水である河川水の濁度が上がっていないのにも関わらず、PACの最適注入濃度が増加するとの報告があった。杵築市浄水場では水道原水の一つとして場内の地下水も利用しており、特にイオン状シリカ濃度が高いことがわかった。水道原水中の高濃度のイオン状シリカと最適PAC注入濃度の定量的関係をジャーテストによって調査し、高濃度のイオン状シリカはPACの凝集剤としての働きを阻害することがわかった。

Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Repository Public URL： http://hdl.handle.net/2324/1929765

Language：English   Publishing type：Research paper (international conference proceedings)  

To reproduce an accurate hydrological cycle condition quantitatively with numerical analysis model, it is essential to incorporate hydraulic geological conditions of the investigated area as clearly as possible. In the previous research, although the river flow discharge was calculated by the TSUTSUMI-JINNO model as will hereinafter be described, the numerical value of the river flow discharge at the most downstream observation point was considerably higher than the observation value. Therefore, hydraulic geological conditions of the basin had to be reconsidered. In this paper, in order to reproduce the actual surface water-groundwater relationship, a new model is developed by adding the following the two conditions: 1)the existence of the former channel of the Obaru river, and 2)phenomenon of groundwater flow out to river as gaining river(stream) is also taken into account the phenomenon of river water flow in to groundwater as losing river(stream) as well. As the results, considering the two phenomena, the calculated river flow discharge and its observed value showed good correlation at the observation point. To reproduce real hydrological cycle condition quantitatively, it is important that evaluating the accurate hydraulic geological conditions in the investigated area are incorporated in the model.

Repository Public URL： http://hdl.handle.net/2324/1929769

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

Kyushu University has been constructing its new campus (Ito Campus) in an area spanning the Motooka-Kuwabara district in Fukuoka City. Agriculture is active in this area and a large amount of groundwater is used for irrigation and horticultural facilities. In recent years, land development for house building has proceeded and one of groundwater recharge sources, paddy area has decreased. Therefore, it is the urgent need to grasp the total amount of groundwater discharge by pumping wells. It was estimated that dividing into three usage ways; for living, agriculture and business. The result shows the daily average groundwater discharge is approximately 635m3 and the percentages of groundwater usage are 59 percent for agriculture, 38 percent for living and 3 percent for business. Next, saline-affected groundwater by effects of groundwater pumping was evaluated from value changes of EC (electrical conductivity), Na and Cl at the wells for agriculture. Consequently, it was revealed that groundwater pumping has an effect on salinization of groundwater and its influences were reflected on the groundwater quality about one month later.

Language：English   Publishing type：Research paper (scientific journal)  

Repository Public URL： http://hdl.handle.net/2324/1929763

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

TWO-DIMENSIONAL TRANSPORT MODEL OF ARSENIC　CONSIDERING THE REDOX REACTION IN GROUNDWATER

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jhazmat.2010.01.008

Repository Public URL： http://hdl.handle.net/2324/4483201

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Probable sources and mechanisms of arsenic (As) release in shallow aquifer in eastern Bangladesh are evaluated using statistical analysis of groundwater compositions. Dissolved As in 39 samples ranged from 8.05 to 341.5 μg/L with an average of 95.14 μg/L. Ninety seven percent of wells exceed the WHO limit (10 μg/L) for safe drinking water. Principal component analysis is applied to reduce 16 measured compositional variables to five significant components (principal components-PCs) that explain 86.63% of the geochemical variance. Two component loadings, namely PC 1 and PC 2 (45.31% and 23.05%) indicate the natural processes within the aquifers in which organic matter is a key reactant in the weathering reactions. Four groups of wells are defined by the PCA and each group of wells represents distinct physicochemical characteristics. Among them, group III groundwater shows higher As concentration together with high concentrations of Fe, Mn, dissolved organic carbon, PO₄³ and HCO₃^- than groups I and II. Speciation calculations suggest that only wells of group III are saturated with respect to siderite, and all groups of samples are supersaturated with respect of rhodochrosite. The relationship of As with these parameters in the different groups of wells of the study area suggests that reductive dissolution of Fe-Mn oxyhydroxides with microbially mediated degradation of organic matter is considered to be the dominant processes to release As in groundwater.

DOI： 10.1007/s10661-009-0760-9

Repository Public URL： http://hdl.handle.net/2324/4400024

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jhazmat.2010.01.008

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s12403-009-0021-8

Repository Public URL： http://hdl.handle.net/2324/4483771

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Groundwater - surface water interaction analysis using a groundwater flow model and radioactive isotopes

Language：English   Publishing type：Research paper (scientific journal)  

Geochemical composition and the level of Arsenic (As) contamination of groundwater in the Ganges Delta Plain, southwestern Bangladesh were elucidated. Hydrogeochemical data of tube well samples suggested that the groundwater is mostly Ca-Mg-HCO₃ type with bicarbonate (HCO₃^-) as the dominant anion, though other type waters are also observed. In contrast, the elevated EC, Cl^- and high content of Na⁺ relative to Ca²⁺, Mg²⁺ and K⁺ in six groundwater samples suggest their saline origin. Low concentrations of NO₃^- and SO₄^2-, and high concentrations of dissolved organic carbon (DOC), HCO₃^- and PO₄^3- indicate the reducing conditions of subsurface aquifer where sediments are deposited with abundant organic matter. The total As concentration in the analyzed samples is very high (0.0431-1.352 mg/L) along with high Fe (2.791-17.058 mg/L) and relatively low Mn (0.134-1.972 mg/L) at different depths. Distinct relationship of As with Fe and Mn, and strong correlation with DOC suggests that the biodegradation of organic matter and reductive dissolution of Fe-oxyhydroxide is considered to be the dominant processes to release As in aquifers. Moreover, negative correlation between As and SO₄^2- demonstrates the As may not be directly mobilized from sulfide minerals like arsenopyrite.

DOI： 10.1016/j.jhazmat.2008.09.046

Repository Public URL： http://hdl.handle.net/2324/4377833

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

IMPLEMENTATION OF STATISTICAL APPROACH FOR EVALUATION OF ARSENIC RELEASE MECHANISM IN GROUNDWATER OF BANGLADESH

Language：Japanese   Publishing type：Research paper (scientific journal)  

THE ANALYSIS FOR THE QUESTIONNAIRE SURVEY ON WATER OF FUKUOKA CITY CITIZENS BY SELF ORGANIZING MAP

Language：English   Publishing type：Research paper (scientific journal)  

The Motooka region in the Fukuoka prefecture in western Japan is a coastal area, where groundwater is utilized as the main water resource for greenhouse agriculture and domestic use. Over-exploitation of groundwater has resulted in seawater intrusion and thus in the contamination of the freshwater aquifer. Fluctuations in electric conductivities caused by such intrusion are a crucial problem, since even slight changes in electric conductivities of the water used for agricultural purposes significantly affect the crops' growth and yield. However, no study has thus far been conducted on the electric conductivity fluctuations caused by groundwater pumping and seasonal recharge of groundwater in the Motooka region. To this end, an attempt is made in the present study to develop a numerical variable-density solute transport model and then apply it to simulate the electric conductivity fluctuations with groundwater pumping and rainwater recharge. This model is developed under a finite difference scheme, and the method of characteristics is used as the numerical technique for solving the advection term of the advection-dispersion solute transport equation. The results from this numerical model are compared with the field measurements.

DOI： 10.1007/s00477-008-0279-6

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Repository Public URL： http://hdl.handle.net/2324/4483768

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Repository Public URL： http://hdl.handle.net/2324/4400016

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Chemical interaction between arsenic and iron with changing redox condition

Language：Japanese   Publishing type：Research paper (scientific journal)  

REDOX PROCESSES BY ROCK-WATER INTERACTION IN SUBSURFACE ENVIRONMENT

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

TRANSPORT MODEL ON BEHAVIOR OF IRON(II) AT SALINITY TRANSITION IN COASTAL AQUIFER

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

Repository Public URL： http://hdl.handle.net/2324/5468

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

Repository Public URL： http://hdl.handle.net/2324/5471

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Coastal groundwater aquifers are often exposed to heavy pumping and consequently to risks of saltwater intrusion. In many cases, however, the observed increase in groundwater salinity can only be partly explained by actual saltwater intrusion from the sea. Other salinity-increasing processes may also significantly contribute to the total salt content of the groundwater. This paper describes a geochemical investigation that was carried out to investigate recent salinity increases in groundwater for the Motooka coastal area in Fukuoka, Japan. A strong increase in electrical conductivity at 15-20 m depth was observed, corresponding to the freshwater and saltwater interface. Oxidation-reduction potentials observed in deeper groundwater were low, indicating long residence time for the groundwater. These results, together with hydrogen-oxygen isotope ratio analysis, indicated that the deeper groundwater is affected by seawater. Consequently, observed tritium concentration in the shallow groundwater system was higher than that of the deeper groundwater system, and a ¹⁴C isotope dating of shell samples collected at 2 m depth indicated an age of about 2000 years. The overall results suggest that the aquifer was originally below the current sea floor and that deeper saline groundwater is not mixed with the shallower fresh groundwater. The deeper groundwater is, therefore, mainly affected by old seawater. In other words, modern saltwater intrusion has not yet occurred even if some wells contain saline water. The study shows that, even though coastal aquifers are heavily pumped, the reason for the rise in groundwater salinity may not necessarily be due to seawater intrusion. Further geochemical and hydrological investigations will be necessary to identify the underlying mechanisms.

DOI： 10.1002/hyp.6099

Repository Public URL： http://hdl.handle.net/2324/4483402

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The spatial distribution of major ion concentration limits the predictability of solute sport processes in field soils. Therefore, it is important to analyze solute transport with chemical reactions based on results obtained from field soils and numerical simulation. A simulation model with cation-exchange reactions was developed and applied to solute-transport analysis of an undisturbed field soil. Chemical reaction terms in the convective-dispersive equation were estimated by the Levenberg-Marquardt nonlinear least-squares regression technique to satisfy physical stud chemical processes simultaneously. The reliability of the model was tested with liquid-phase and solid-phase concentrations of measured spatial distributions of Ca²⁺, Mg²⁺, Na⁺, and K⁺ after continuous infiltration of KCl solution into an undisturbed soft column. The experimental results revealed that the selectivity coefficients for Ca-Na and Co-Mg exchange could be kept constant, while those for Ca-K exchange increased with the equivalent fraction of K⁺ in the solid phase. The effects of the exchange selectivity coefficient on reactive solute transport are discussed based on the simulation results. When a constant selectivity coefficient was used, the model failed to predict the spatial distributions of cation concentrations in the solid phase. Thus, model predictions can be improved by use of variable instead of constant selectivity coefficients.

DOI： 10.2136/sssaj1997.03615995006100060001x

Repository Public URL： http://hdl.handle.net/2324/4483765

Language：English   Publishing type：Research paper (other academic)  

Over-exploitation of groundwater in coastal aquifers is one of the major reasons for saltwater intrusion. Saltwater intrusion contaminates the freshwater resource in coastal aquifers by increasing the salinity levels of the groundwater. A small quantity of saltwater is enough to contaminate the large quantity of freshwater in a coastal aquifer. Therefore, saltwater intrusion should be considered seriously. Numerical models are needed to enhance the understanding of saltwater intrusion and its related phenomena extensively. The Motooka region in the Fukuoka prefecture in Japan is a coastal area, where groundwater is the main water resource for green house agriculture and domestic use. Over-exploitation of groundwater in this coastal region has resulted in saltwater intrusion and thus in the contamination of the freshwater aquifer. In addition to the more obvious effects of saltwater intrusion, fluctuations in salinity caused by such intrusion is a crucial problem to address, since even slight changes in salinity of the water use for agricultural purposes significantly affect the crop's growth and yield. So far, a research on the salinity fluctuations with groundwater pumping and their effects on seasonal recharge of groundwater in the Motooka region has not been conducted. Therefore, in this study a three-dimensional density-dependent solute transport flow model is developed to simulate the salinity fluctuations due to groundwater pumping. In the present numerical study, the emphasis is on the development of conceptual, mathematical and numerical model of variable density flow and solute transport and its application to simulate the salinity fluctuation due to groundwater pumping at different rates. The model is based on the “transition zone” approach, which considers the interface as a miscible zone where freshwater and saltwater is mixing while maintaining a density gradient across the freshwater/saltwater interface. The transition zone approach requires simultaneous solutions of the governing water flow and solute transport equations. To this end, the model incorporates three fundamental equations in flow and solute transport, namely Darcy's law, general groundwater flow equation and the advection dispersion solute transport equation. The groundwater flow equation and solute transport equation are coupled by the equation of state to produce the salt concentration at each time step for whole flow domain. The finite difference method is used as the numerical technique to solve the partial differential equations of flow and transport under an implicit scheme. The method of characteristics is applied to solve the advection term in the solute transport equation. A non-uniform discretized grid system is adopted in the flow domain allocating relatively small grid sizes to pumping well locations. To achieve reliable results, relevant and important hydro-geological parameters are assigned to the numerical model after considering the hydrological situation of the Motooka region. Different boundary conditions are assigned considering the dominant hydrological processes those are believed to be in effect in the selected area. The numerical results obtained from the model demonstrate the salinity variation due to groundwater pumping and seasonal recharge rates from year 2001 to 2007 under the influence of saltwater intrusion. The results also reveal that model is capable of correctly simulating the physical processes. A comparison of the measured and modeled electric conductivities shows reasonable agreement.

Language：English   Publishing type：Research paper (scientific journal)  

Geochemical characteristics of shallow groundwaters and core sediments are studied to better understand the sources and transportation process responsible for As and Mn enrichment in Singair Upazila of Manikgonj District in Bangladesh. Results demonstrate that the groundwater is mostly of Ca-HCO₃ and Ca-Mg-HCO₃ types. Concentrations of As in groundwater ranged from 1 to 159 μg/L, with about 59% of these exceeded the WHO drinking water guideline of 10 mg/L. In addition, all groundwater samples had higher concentrations of Mn (0.6-5.7 mg/L) and Fe (0.9-16.5 mg/L) than the WHO drinking water guidelines (0.4 and 0.3 μg/L, respectively). Most groundwaters contained both As(III) and As(V) species in which the concentration of As(III) was generally higher than that of As(V). High concentration of As (23 mg/kg) with elevated levels of FeO, MnO and TOC were found within the upper 15 m of silty clay sediments. Multivariate geostatistical analysis showed that dissolution of the Fe-Mn oxides was the dominant process of As and Mn release in groundwater. Geochemical modeling suggested that the concentrations of As, Mn, Fe and PO₄^3- in groundwaters were also influenced by secondary minerals phases in addition to redox processes.

DOI： 10.1007/s13369-014-1111-x

Repository Public URL： http://hdl.handle.net/2324/4372011

Language：English   Publishing type：Research paper (scientific journal)  

There is a tremendous demand for developing efficient methods for arsenic removal from drinking waters due to its severe toxicity effect on living beings. In order to predict an appropriate technique for arsenic removal from groundwater a numerical model that is able to describe the removal of arsenic and other background species from the groundwater considering chemical and biochemical processes has been developed in the present paper. Based on the adsorption/co-precipitation of arsenic with iron(III) hydroxides, the behavior of arsenic and iron under oxidation dominant environment including advection, dispersion, molecular diffusion and the microbially mediated chemical processes are also presented. The arsenic transport equation and the balance equations are solved numerically using the finite difference method and method of characteristics (MOC), subject to prescribed initial and boundary conditions are also presented. The kinetic sub model describes the heterotrophic metabolisms of several groups of microorganisms. Microbial growth is assumed to follow Monod type kinetics. The results of the removal simulation model demonstrated that availability of substrate (e.g. organic carbon), maximum growth rate, yield coefficient of bacteria, the precipitation rate of iron-hydroxide and the adsorption/precipitation rate of arsenic with iron hydroxide were important parameters which affected the removal of arsenic from groundwater. Among all the parameters organic carbon concentration proved as the most important.

Language：English   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (scientific journal)  

A three-dimensional mathematical model of variable density groundwater flow and miscible solute transport is developed to investigate the saltwater contamination of a coastal aquifer in west Japan. The selected area is an agricultural region located on a coastal aquifer where the groundwater is being consumed continuously as the main water source for drinking, greenhouses and industries. The salinity of the pumped water has been analysed periodically and it has been found that the threat of saltwater intrusion is emerging due to the continuous exploitation of groundwater. Owing to the distributed nature of pumping-well locations and nonuniform geological conditions, a three-dimensional model is needed to understand the saline contamination of the coastal aquifer. A numerical model was built by using the finite difference framework, taking into account the development of a transition zone and the variation of fluid density within it. The model simulates the saturated and unsaturated zone groundwater flow under the influence of a variable density situation in the coastal aquifer. Moreover, it can be used as a numerical tool to simulate the salinity contamination of the freshwater in this coastal aquifer.

DOI： 10.1680/wama.2010.163.7.367

Repository Public URL： http://hdl.handle.net/2324/4479077

Language：English  

The Motooka area of Fukuoka prefecture of Japan is an agricultural area located on a coastal aquifer where the groundwater is being exploited for drinking and green house agriculture. The groundwater is the main water supply for drinking and greenhouse agriculture. With the increased water demand, groundwater is being extracted at the rate of 1,200m³/day. The salinity of the pumped water has been analyzed periodically and it has found that the aquifer is affected by the saltwater intrusion due to over exploitation of groundwater. The high salinity of pumped water is not suitable for both drinking and greenhouse farming. The salinity fluctuation in the pumped groundwater has become an important issue to attract much attention of the green house farmers due to its significant effect on their crops. To the authors' knowledge, research on the salinity fluctuations with groundwater pumping and their effects on seasonal recharge of groundwater in the Motooka region has not been conducted thus far. In the field of numerical modeling of saltwater intrusion, so far the simulation of salinity fluctuations is not significant. Therefore authors found a keen interest on numerical simulation of the saltwater intrusion and the salinity fluctuation phenomenon in the Motooka. To this end, a three dimensional density dependent finite difference solute transport numerical model was developed. Due to the distributed nature of pumping well locations and non-uniform geological conditions; a three-dimensional model was needed to understand the saltwater intrusion and salinity fluctuations in the Motooka. The developed model is capable of simulating the saltwater intrusion and the salinity fluctuations due to groundwater pumping for satisfactory extent.

DOI： 10.1142/7158-vol17

Language：English  

The Motooka area of Fukuoka prefecture of Japan is an agricultural area located on a coastal aquifer where the groundwater is being exploited for drinking and green house agriculture. The groundwater is the main water supply for drinking and greenhouse agriculture. With the increased water demand, groundwater is being extracted at the rate of 1,200m³/day. The salinity of the pumped water has been analyzed periodically and it has found that the aquifer is affected by the saltwater intrusion due to over exploitation of groundwater. The high salinity of pumped water is not suitable for both drinking and greenhouse farming. The salinity fluctuation in the pumped groundwater has become an important issue to attract much attention of the green house farmers due to its significant effect on their crops. To the authors' knowledge, research on the salinity fluctuations with groundwater pumping and their effects on seasonal recharge of groundwater in the Motooka region has not been conducted thus far. In the field of numerical modeling of saltwater intrusion, so far the simulation of salinity fluctuations is not significant. Therefore authors found a keen interest on numerical simulation of the saltwater intrusion and the salinity fluctuation phenomenon in the Motooka. To this end, a three dimensional density dependent finite difference solute transport numerical model was developed. Due to the distributed nature of pumping well locations and non-uniform geological conditions; a three-dimensional model was needed to understand the saltwater intrusion and salinity fluctuations in the Motooka. The developed model is capable of simulating the saltwater intrusion and the salinity fluctuations due to groundwater pumping for satisfactory extent.

DOI： 10.1142/7158-vol17

Language：English  

The Motooka area of Fukuoka prefecture of Japan is an agricultural area located on a coastal aquifer where the groundwater is being exploited for drinking and green house agriculture. The groundwater is the main water supply for drinking and greenhouse agriculture. With the increased water demand, groundwater is being extracted at the rate of 1,200m³/day. The salinity of the pumped water has been analyzed periodically and it has found that the aquifer is affected by the saltwater intrusion due to over exploitation of groundwater. The high salinity of pumped water is not suitable for both drinking and greenhouse farming. The salinity fluctuation in the pumped groundwater has become an important issue to attract much attention of the green house farmers due to its significant effect on their crops. To the authors' knowledge, research on the salinity fluctuations with groundwater pumping and their effects on seasonal recharge of groundwater in the Motooka region has not been conducted thus far. In the field of numerical modeling of saltwater intrusion, so far the simulation of salinity fluctuations is not significant. Therefore authors found a keen interest on numerical simulation of the saltwater intrusion and the salinity fluctuation phenomenon in the Motooka. To this end, a three dimensional density dependent finite difference solute transport numerical model was developed. Due to the distributed nature of pumping well locations and non-uniform geological conditions; a three-dimensional model was needed to understand the saltwater intrusion and salinity fluctuations in the Motooka. The developed model is capable of simulating the saltwater intrusion and the salinity fluctuations due to groundwater pumping for satisfactory extent.

DOI： 10.1142/7158-vol17

Language：English   Publishing type：Research paper (other academic)  

The Motooka region in Fukuoka, Japan is a coastal region where agriculture is dominant. The green houses and wineries cover their water demand from groundwater. With the increased water demand, seawater intrusion is identified as an alarming threat to the Motooka coastal aquifer in near future. The measured electric conductivities of the water samples have been analyzed periodically. Until now the measured electric conductivities do not show high values but those values convince the emerging threat of seawater intrusion in this aquifer in future if groundwater will be pumped at current rate further. Therefore it is worth to conduct a numerical study of seawater intrusion and its impact to the Motooka area since the sustainability of the aquifer is inevitable for the future groundwater development and agriculture. In this paper a numerical study of the seawater intrusion of the Motooka is discussed. The numerical model presented in this paper was developed by coupling the groundwater flow equation with the mass transport equation to simulate the density dependent solute transport in the three dimensional space. The usage of this model as a management tool to simulate the salinity variation with groundwater pumping is emphasized. The numerical model was adequately capable of simulating the seawater intrusion and numerical results show a satisfactory agreement with the field observations.

Language：English   Publishing type：Research paper (other academic)  

Over-exploitation of groundwater in coastal aquifers is one of the major reasons for saltwater intrusion. Saltwater intrusion contaminates the freshwater resource in coastal aquifers by increasing the salinity levels of the groundwater. A small quantity of saltwater is enough to contaminate the large quantity of freshwater in a coastal aquifer. Therefore, saltwater intrusion should be considered seriously. Numerical models are needed to enhance the understanding of saltwater intrusion and its related phenomena extensively. The Motooka region in the Fukuoka prefecture in Japan is a coastal area, where groundwater is the main water resource for green house agriculture and domestic use. Over-exploitation of groundwater in this coastal region has resulted in saltwater intrusion and thus in the contamination of the freshwater aquifer. In addition to the more obvious effects of saltwater intrusion, fluctuations in salinity caused by such intrusion is a crucial problem to address, since even slight changes in salinity of the water use for agricultural purposes significantly affect the crop's growth and yield. So far, a research on the salinity fluctuations with groundwater pumping and their effects on seasonal recharge of groundwater in the Motooka region has not been conducted. Therefore, in this study a three-dimensional density-dependent solute transport flow model is developed to simulate the salinity fluctuations due to groundwater pumping. In the present numerical study, the emphasis is on the development of conceptual, mathematical and numerical model of variable density flow and solute transport and its application to simulate the salinity fluctuation due to groundwater pumping at different rates. The model is based on the "transition zone"approach, which considers the interface as a miscible zone where freshwater and saltwater is mixing while maintaining a density gradient across the freshwater/saltwater interface. The transition zone approach requires simultaneous solutions of the governing water flow and solute transport equations. To this end, the model incorporates three fundamental equations in flow and solute transport, namely Darcy's law, general groundwater flow equation and the advection dispersion solute transport equation. The groundwater flow equation and solute transport equation are coupled by the equation of state to produce the salt concentration at each time step for whole flow domain. The finite difference method is used as the numerical technique to solve the partial differential equations of flow and transport under an implicit scheme. The method of characteristics is applied to solve the advection term in the solute transport equation. A non-uniform discretized grid system is adopted in the flow domain allocating relatively small grid sizes to pumping well locations. To achieve reliable results, relevant and important hydro-geological parameters are assigned to the numerical model after considering the hydrological situation of the Motooka region. Different boundary conditions are assigned considering the dominant hydrological processes those are believed to be in effect in the selected area. The numerical results obtained from the model demonstrate the salinity variation due to groundwater pumping and seasonal recharge rates from year 2001 to 2007 under the influence of saltwater intrusion. The results also reveal that model is capable of correctly simulating the physical processes. A comparison of the measured and modeled electric conductivities shows reasonable agreement.

Language：English   Publishing type：Research paper (other academic)  

The Motooka region in Fukuoka, Japan is a coastal region where agriculture is dominant. The green houses and wineries cover their water demand from groundwater. With the increased water demand, seawater intrusion is identified as an alarming threat to the Motooka coastal aquifer in near future. The measured electric conductivities of the water samples have been analyzed periodically. Until now the measured electric conductivities do not show high values but those values convince the emerging threat of seawater intrusion in this aquifer in future if groundwater will be pumped at current rate further. Therefore it is worth to conduct a numerical study of seawater intrusion and its impact to the Motooka area since the sustainability of the aquifer is inevitable for the future groundwater development and agriculture. In this paper a numerical study of the seawater intrusion of the Motooka is discussed. The numerical model presented in this paper was developed by coupling the groundwater flow equation with the mass transport equation to simulate the density dependent solute transport in the three dimensional space. The usage of this model as a management tool to simulate the salinity variation with groundwater pumping is emphasized. The numerical model was adequately capable of simulating the seawater intrusion and numerical results show a satisfactory agreement with the field observations.

Language：English   Publishing type：Research paper (scientific journal)  

A one dimensional reactive transport model was developed in order to illustrate the biogeochemical behavior of arsenic and iron reduction and release to groundwater that accounts for the reaction coupling the major redox elements under reducing environment. Mass transport equation and the method of characteristics were used considering fundamental geochemical processes to simulate transport processes of different pollutants in mobile phase. The kinetic sub-model describes the heterotrophic metabolisms of several microorganisms. To model a complete redox sequence (aerobic or denitrifiers, Fe(III)-reduction, respiration bacteria of iron and arsenic compounds, and As(V) reduction) four functional bacterial groups (X₁, X₂, X₃, and X₄) were defined. Microbial growth was assumed to follow Monod type kinetics. The exchange between the different phases (mobile, bio, and matrix) was also considered in this approach. Results from a soil column experiment were used to verify the simulation results of the model. The model depicts the utilization of oxygen, nitrate, iron oxide and arsenic as electron acceptors for oxidation of organic carbon (OC) in a column. The OC as electron donor is one of the most important factors that affect the iron and arsenic reduction bacterial activity.

DOI： 10.1007/s00254-008-1517-4

Repository Public URL： http://hdl.handle.net/2324/4363102

Language：English   Publishing type：Research paper (scientific journal)  

An integrated study has been carried out to elucidate the distribution and occurrence of arsenic in selected groundwater samples in the area of Sherajdikhan, Bangladesh. Arsenic and other parameters (T, pH, EC, Na ⁺, K⁺, Ca²⁺, Mg²⁺, Cl^-, NO₃ ^-, SO₄ ^2-, HCO₃ ^-, PO₄ ^3-, Fe, Mn and DOC) have been measured in groundwater samples collected from shallow/deep tube wells at different depths. Hydrogeochemical data suggest that the groundwaters are generally Ca-Mg-HCO₃ and Mg-Ca-HCO₃ types with bicarbonate (HCO ₃ ^-) as the dominant anion, though the other type of water has also been observed. Dissolved arsenic in groundwater ranged from 0.006 to 0.461 mg/l, with 69% groundwater samples exceeded the Bangladesh limit for safe drinking water (0.05 mg/l). Correlation and principal component analysis have been performed to find out possible relationships among the examined parameters in groundwater. Low concentrations of NO₃ ^- and SO ₄ ^2-, and high concentrations of DOC, HCO₃ ^- and PO₄ ^3- indicate the reducing condition of subsurface aquifer where sediments are deposited with abundant organic matter. Distinct relationship of As with Fe and Mn, and strong correlation with DOC suggests that the biodegradation of organic matter along with reductive dissolution of Fe-Mn oxyhydroxides has being considered the dominant process to release As in the aquifers studied herein.

DOI： 10.1007/s00254-008-1493-8

Repository Public URL： http://hdl.handle.net/2324/4483766

Language：English   Publishing type：Research paper (scientific journal)  

A one dimensional reactive transport model was developed in order to illustrate the biogeochemical behavior of arsenic and iron reduction and release to groundwater that accounts for the reaction coupling the major redox elements under reducing environment. Mass transport equation and the method of characteristics were used considering fundamental geochemical processes to simulate transport processes of different pollutants in mobile phase. The kinetic sub-model describes the heterotrophic metabolisms of several microorganisms. To model a complete redox sequence (aerobic or denitrifiers, Fe(III)-reduction, respiration bacteria of iron and arsenic compounds, and As(V) reduction) four functional bacterial groups (X₁, X₂, X₃, and X₄) were defined. Microbial growth was assumed to follow Monod type kinetics. The exchange between the different phases (mobile, bio, and matrix) was also considered in this approach. Results from a soil column experiment were used to verify the simulation results of the model. The model depicts the utilization of oxygen, nitrate, iron oxide and arsenic as electron acceptors for oxidation of organic carbon (OC) in a column. The OC as electron donor is one of the most important factors that affect the iron and arsenic reduction bacterial activity.

DOI： 10.1007/s00254-008-1517-4

Language：English   Publishing type：Research paper (scientific journal)  

An integrated study has been carried out to elucidate the distribution and occurrence of arsenic in selected groundwater samples in the area of Sherajdikhan, Bangladesh. Arsenic and other parameters (T, pH, EC, Na ⁺, K⁺, Ca²⁺, Mg²⁺, Cl^-, NO₃ ^-, SO₄ ^2-, HCO₃ ^-, PO₄ ^3-, Fe, Mn and DOC) have been measured in groundwater samples collected from shallow/deep tube wells at different depths. Hydrogeochemical data suggest that the groundwaters are generally Ca-Mg-HCO₃ and Mg-Ca-HCO₃ types with bicarbonate (HCO ₃ ^-) as the dominant anion, though the other type of water has also been observed. Dissolved arsenic in groundwater ranged from 0.006 to 0.461 mg/l, with 69% groundwater samples exceeded the Bangladesh limit for safe drinking water (0.05 mg/l). Correlation and principal component analysis have been performed to find out possible relationships among the examined parameters in groundwater. Low concentrations of NO₃ ^- and SO ₄ ^2-, and high concentrations of DOC, HCO₃ ^- and PO₄ ^3- indicate the reducing condition of subsurface aquifer where sediments are deposited with abundant organic matter. Distinct relationship of As with Fe and Mn, and strong correlation with DOC suggests that the biodegradation of organic matter along with reductive dissolution of Fe-Mn oxyhydroxides has being considered the dominant process to release As in the aquifers studied herein.

DOI： 10.1007/s00254-008-1493-8

Language：English   Publishing type：Research paper (scientific journal)  

Geochemical composition and the level of Arsenic (As) contamination of groundwater in the Ganges Delta Plain, southwestern Bangladesh were elucidated. Hydrogeochemical data of tube well samples suggested that the groundwater is mostly Ca-Mg-HCO₃ type with bicarbonate (HCO₃^-) as the dominant anion, though other type waters are also observed. In contrast, the elevated EC, Cl^- and high content of Na⁺ relative to Ca²⁺, Mg²⁺ and K⁺ in six groundwater samples suggest their saline origin. Low concentrations of NO₃^- and SO₄^2-, and high concentrations of dissolved organic carbon (DOC), HCO₃^- and PO₄^3- indicate the reducing conditions of subsurface aquifer where sediments are deposited with abundant organic matter. The total As concentration in the analyzed samples is very high (0.0431-1.352 mg/L) along with high Fe (2.791-17.058 mg/L) and relatively low Mn (0.134-1.972 mg/L) at different depths. Distinct relationship of As with Fe and Mn, and strong correlation with DOC suggests that the biodegradation of organic matter and reductive dissolution of Fe-oxyhydroxide is considered to be the dominant processes to release As in aquifers. Moreover, negative correlation between As and SO₄^2- demonstrates the As may not be directly mobilized from sulfide minerals like arsenopyrite.

DOI： 10.1016/j.jhazmat.2008.09.046

Repository Public URL： http://hdl.handle.net/2324/4483769

Language：English   Publishing type：Research paper (scientific journal)  

The Motooka region in the Fukuoka prefecture in western Japan is a coastal area, where groundwater is utilized as the main water resource for greenhouse agriculture and domestic use. Over-exploitation of groundwater has resulted in seawater intrusion and thus in the contamination of the freshwater aquifer. Fluctuations in electric conductivities caused by such intrusion are a crucial problem, since even slight changes in electric conductivities of the water used for agricultural purposes significantly affect the crops' growth and yield. However, no study has thus far been conducted on the electric conductivity fluctuations caused by groundwater pumping and seasonal recharge of groundwater in the Motooka region. To this end, an attempt is made in the present study to develop a numerical variable-density solute transport model and then apply it to simulate the electric conductivity fluctuations with groundwater pumping and rainwater recharge. This model is developed under a finite difference scheme, and the method of characteristics is used as the numerical technique for solving the advection term of the advection-dispersion solute transport equation. The results from this numerical model are compared with the field measurements.

DOI： 10.1007/s00477-008-0279-6

Repository Public URL： http://hdl.handle.net/2324/4483768

Language：English   Publishing type：Research paper (other academic)  

Groundwater discharge to sea areas affects environmental conditions along coasts. Enclosed bays may experience eutrophication caused by nutrient input from land areas through groundwater discharge since groundwater is often contaminated by large amounts of nutrients as compared with river water. Therefore, it is necessary to estimate the groundwater discharge into seas quantitatively in order to understand nutrient pathways. A distributed groundwater recharge model was developed in order to estimate total groundwater discharge flow into the Ariake Bay, in Kyushu, Japan. The Komoda catchment within the Kikuchi River basin in Kumamoto prefecture was studied as a representative area for the Ariake Bay. The model partitions rainfall into direct runoff, evapotranspiration, and groundwater recharge. Parameters are set based on land use. Groundwater discharge is calculated using a water balance approach. The results show that groundwater discharge into the Ariake Bay from Kukuchi River basin is on average 123 mm year^-1. The groundwater discharge accounts for about 8% of total water discharge and 9% of river discharge. The results can be used to better estimate annual transport of nutrients in the groundwater to the sea and thus also to better manage eutrophication problems.

Language：English   Publishing type：Research paper (other academic)  

Groundwater discharge to sea areas affects environmental conditions along coasts. Enclosed bays may experience eutrophication caused by nutrient input from land areas through groundwater discharge since groundwater is often contaminated by large amounts of nutrients as compared with river water. Therefore, it is necessary to estimate the groundwater discharge into seas quantitatively in order to understand nutrient pathways. A distributed groundwater recharge model was developed in order to estimate total groundwater discharge flow into the Ariake Bay, in Kyushu, Japan. The Komoda catchment within the Kikuchi River basin in Kumamoto prefecture was studied as a representative area for the Ariake Bay. The model partitions rainfall into direct runoff, evapotranspiration, and groundwater recharge. Parameters are set based on land use. Groundwater discharge is calculated using a water balance approach. The results show that groundwater discharge into the Ariake Bay from Kukuchi River basin is on average 123 mm year^-1. The groundwater discharge accounts for about 8% of total water discharge and 9% of river discharge. The results can be used to better estimate annual transport of nutrients in the groundwater to the sea and thus also to better manage eutrophication problems.

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (other academic)  

Oxidation-reduction geochemical processes coupled with mass transport in a coastal aquifer is a unique subsurface environmental phenomenon to model. When a porous material is contaminated by organic carbons, nitrate is denitrified and manganese dioxide and oxi-iron hydroxide would be reduced. However, it is expected that the reduced divalent iron is oxidized once again by seawater when discharged to the sea. The paper discusses a numerical model of transport and geochemical reaction processes along the mixing zone of fresh and reduced salt water in a coastal aquifer. By comparing the numerical solution with experimental observations for the precipitation of divalent iron along the mixing zone, the validity of the model is demonstrated.

Language：English   Publishing type：Research paper (other academic)  

Oxidation-reduction geochemical processes coupled with mass transport in a coastal aquifer is a unique subsurface environmental phenomenon to model. When a porous material is contaminated by organic carbons, nitrate is denitrified and manganese dioxide and oxi-iron hydroxide would be reduced. However, it is expected that the reduced divalent iron is oxidized once again by seawater when discharged to the sea. The paper discusses a numerical model of transport and geochemical reaction processes along the mixing zone of fresh and reduced salt water in a coastal aquifer. By comparing the numerical solution with experimental observations for the precipitation of divalent iron along the mixing zone, the validity of the model is demonstrated.

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (scientific journal)  

Seawater intrusion is identified as a critical issue that needs to be addressed in coastal hydrology, due its irreversible effect on the water quality of coastal freshwater aquifers. Due to the density differences in seawater and freshwater, the density dependent flow phenomenon is dominant seawater intrusion. Three dimensional numerical model is necessary to address the complex hydro-geological formations. Therefore, it is important to develop a three dimensional simulation model to understand the density dependent solute transport process taking place in the seawater intrusion problem. The model developed in this study is based on the transition zone approach which couples the groundwater flow and mass transport equation to solve the density dependent flow. The finite difference method is used as the numerical method to solve the partial difference equations of groundwater flow and solute transport. The method of characteristic is applied to solve the advection term of mass transport equation. Therefore, in this paper, a valued attempt has been taken to simulate the seawater intrusion in the three dimensional point of view under the density dependent flow effect. Motooka area of Fukuoka Prefecture Japan which is a coastal area is selected as an application area for the developed model to emphasize seawater intrusion and justify the model. This area is affected by seawater intrusion and so far numerical study of seawater intrusion under the density dependent flow concept has not performed.

Language：English   Publishing type：Research paper (scientific journal)  

Seawater intrusion is identified as a critical issue that needs to be addressed in coastal hydrology, due its irreversible effect on the water quality of coastal freshwater aquifers. Due to the density differences in seawater and freshwater, the density dependent flow phenomenon is dominant seawater intrusion. Three dimensional numerical model is necessary to address the complex hydro-geological formations. Therefore, it is important to develop a three dimensional simulation model to understand the density dependent solute transport process taking place in the seawater intrusion problem. The model developed in this study is based on the transition zone approach which couples the groundwater flow and mass transport equation to solve the density dependent flow. The finite difference method is used as the numerical method to solve the partial difference equations of groundwater flow and solute transport. The method of characteristic is applied to solve the advection term of mass transport equation. Therefore, in this paper, a valued attempt has been taken to simulate the seawater intrusion in the three dimensional point of view under the density dependent flow effect. Motooka area of Fukuoka Prefecture Japan which is a coastal area is selected as an application area for the developed model to emphasize seawater intrusion and justify the model. This area is affected by seawater intrusion and so far numerical study of seawater intrusion under the density dependent flow concept has not performed.

Language：English   Publishing type：Research paper (scientific journal)  

Groundwater contamination has been rising as a critical issue to be solved. Prediction of distribution and fate of different contaminants need to be obtained prior to designing an appropriate monitoring and remediation scheme. To model bacteria mediated redox processes a one-dimensional, multi-component reactive transport model that accounts for the reaction coupling the major redox elements was presented. Mass transport equation was used to simulate transport processes of different pollutants. For the numerical modelling of mass transport in the mobile phase, the method of characteristics was used considering fundamental geochemical processes. Then, solute transport was coupled to microbially mediated organic carbon degradation. To model a complete redox sequence (aerobic or denitrifiers, Mn(IV)-reduction, Fe(III)-reduction, respiration bacteria of iron and arsenic compounds, and As(V) reduction) five functional bacterial groups (X₁, X₂, X₃, X ₄ and X₅) were defined. Microbial growth was assumed to follow Monod type kinetics. The exchange between the different phases (mobile, bio, and matrix) was also considered in this approach. Results from a soil column experiment were used to verify the simulation results of the model. It was concluded that the transport model provides a useful framework for predicting the transport of arsenic in the groundwater aquifer.

Language：English   Publishing type：Research paper (scientific journal)  

Groundwater contamination has been rising as a critical issue to be solved. Prediction of distribution and fate of different contaminants need to be obtained prior to designing an appropriate monitoring and remediation scheme. To model bacteria mediated redox processes a one-dimensional, multi-component reactive transport model that accounts for the reaction coupling the major redox elements was presented. Mass transport equation was used to simulate transport processes of different pollutants. For the numerical modelling of mass transport in the mobile phase, the method of characteristics was used considering fundamental geochemical processes. Then, solute transport was coupled to microbially mediated organic carbon degradation. To model a complete redox sequence (aerobic or denitrifiers, Mn(IV)-reduction, Fe(III)-reduction, respiration bacteria of iron and arsenic compounds, and As(V) reduction) five functional bacterial groups (X₁, X₂, X₃, X ₄ and X₅) were defined. Microbial growth was assumed to follow Monod type kinetics. The exchange between the different phases (mobile, bio, and matrix) was also considered in this approach. Results from a soil column experiment were used to verify the simulation results of the model. It was concluded that the transport model provides a useful framework for predicting the transport of arsenic in the groundwater aquifer.

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Spring water, however, is often formed in complex geological formations and therefore it is difficult to determine the catchment area contributing to the flow. The Sayanokami spring, located in western part of Fukuoka City, Japan, is such a spring and an important water resource for the local agriculture. In order to better understand the hydrological properties of infiltration and groundwater processes for the spring water, ²²²Rn and tritium were used as tracers. Results showed that the residence time for the spring water is 10 - 20 years. A groundwater model confirmed these results and the travel time from the catchment border estimated to be about 25 years. Using this information the catchment border and uptake area were estimated. The method can be used to more efficiently determine catchment area and travel time for groundwater and thus to better manage the spring water.

Language：English   Publishing type：Research paper (scientific journal)  

This paper presents the estimation of the parameters F_∞, and (r)_1/2 used in the groimdwater recharge model by separating the surface runoff component for isolated rainfall event. The time-area distribution method was used. Several types of land use were considered. The watershed of the upstream of Sakurai River at Suematsu Bridge in Itoshlma Peninsula which includes the western part of the new campus (Ito campus) area of Kyushu University in southern Japan, was selected as a site study to test the model approach. Since more than 80% of study area is covered with forest, the proposed model considers rainfall interception by forest canopy. The runoff parameters F_∞ and (r)_1/2 were identified in this study using records of river discharge at the outlet point of the watershed. The results indicate that the separation approach satisfactorily predicted runoff parameters for different land use, and also showed that simulated runoff results agree well with observed results.

Language：English   Publishing type：Research paper (scientific journal)  

Spring water, however, is often formed in complex geological formations and therefore it is difficult to determine the catchment area contributing to the flow. The Sayanokami spring, located in western part of Fukuoka City, Japan, is such a spring and an important water resource for the local agriculture. In order to better understand the hydrological properties of infiltration and groundwater processes for the spring water, ²²²Rn and tritium were used as tracers. Results showed that the residence time for the spring water is 10 - 20 years. A groundwater model confirmed these results and the travel time from the catchment border estimated to be about 25 years. Using this information the catchment border and uptake area were estimated. The method can be used to more efficiently determine catchment area and travel time for groundwater and thus to better manage the spring water.

Language：English   Publishing type：Research paper (scientific journal)  

This paper presents the estimation of the parameters F_∞, and (r)_1/2 used in the groimdwater recharge model by separating the surface runoff component for isolated rainfall event. The time-area distribution method was used. Several types of land use were considered. The watershed of the upstream of Sakurai River at Suematsu Bridge in Itoshlma Peninsula which includes the western part of the new campus (Ito campus) area of Kyushu University in southern Japan, was selected as a site study to test the model approach. Since more than 80% of study area is covered with forest, the proposed model considers rainfall interception by forest canopy. The runoff parameters F_∞ and (r)_1/2 were identified in this study using records of river discharge at the outlet point of the watershed. The results indicate that the separation approach satisfactorily predicted runoff parameters for different land use, and also showed that simulated runoff results agree well with observed results.

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (scientific journal)  

Within the Ito Campus and surrounding area, subsurface investigations with several borings had been conducted by the Kyushu University. Core samples obtained by the boring and groundwater samples collected from the boring wells provide important information on understanding geological and geochemical features of this area. Age determination of a lamprophyre dike in the Itoshima Granitoid using K-Ar technique provided age of around 90.7 ± 1.2 Ma, which is in accordance with the reported age for main body of the granitoid. This result would be one of constraints for discussion on igneous activities in the northern Kyushu. The groundwater collected from this area can be classified into four types based on the chemical and isotopic compositions. The relationship between water chemistry and water elevation can be explained as a snap shot of groundwater evolution from meteoric water to the Ca-HCO₃ type groundwater accompanying weathering of granitic rocks. Within the alluvial sediments in the east of the Ito Campus, the Na-Cl type groundwater is widely distributed, which is attributed to the influence of seawater intrusion. The natural flow which is associated with the West Off Fukuoka Earthquake on March 20, 2005 is explained as a result of rising of the freshwater-seawater boundary.

Language：English   Publishing type：Research paper (scientific journal)  

Within the Ito Campus and surrounding area, subsurface investigations with several borings had been conducted by the Kyushu University. Core samples obtained by the boring and groundwater samples collected from the boring wells provide important information on understanding geological and geochemical features of this area. Age determination of a lamprophyre dike in the Itoshima Granitoid using K-Ar technique provided age of around 90.7 ± 1.2 Ma, which is in accordance with the reported age for main body of the granitoid. This result would be one of constraints for discussion on igneous activities in the northern Kyushu. The groundwater collected from this area can be classified into four types based on the chemical and isotopic compositions. The relationship between water chemistry and water elevation can be explained as a snap shot of groundwater evolution from meteoric water to the Ca-HCO₃ type groundwater accompanying weathering of granitic rocks. Within the alluvial sediments in the east of the Ito Campus, the Na-Cl type groundwater is widely distributed, which is attributed to the influence of seawater intrusion. The natural flow which is associated with the West Off Fukuoka Earthquake on March 20, 2005 is explained as a result of rising of the freshwater-seawater boundary.

Language：English   Publishing type：Research paper (other academic)  

The identification of release mechanisms of arsenic may assist in designing safe and effective remediation strategies, due to its severe toxicity effect for the human body. In this regards, investigations were carried out to observe the release of As from soil into water. It was found that As concentration increased with decreasing oxidation reduction potential. Arsenic concentrations demonstrated negative covariation with the concentrations of NO₃ but strongly correlated with DOC and Fe concentrations. Batch leaching tests at different pH conditions showed a strong pH dependence on arsenic and iron leaching. A numerical simulation of arsenic transport model, coupled with microbially mediated biogeochemical processes was developed for describing the release of As in soil under reducing environment. The simulation concentrations of Mn, Fe and As were well matched those found experimentally. The results of this study suggested that the microbially mediated degradation of organic matter and reductive dissolution of Fe-oxyhydroxide are considered to be the dominant processes to release As in aquifers.

Language：English   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (other academic)  

Submarine groundwater discharge (SGD) is now recognized as an important pathway between land and sea. This study attempts to estimate the nutrient inputs through SGD to Ariake Bay. SGD rates and its quality along the coast of Ariake Bay in the Oura Region, Japan, were investigated. It was shown that the on-site SGD rate ranges from 0.01 to 20.52 μm/s, and SGD flows through the shallow confined aquifers, which consist of two kinds of rocks: basalt and pyroclastic rocks. The reduction reaction for SGD proceeded just up to denitrification. SGD associated with nutrient loads of N, P and SiO₂ were estimated to be 1.40, 0.07 and 52.78 g m^-2 d^-1, respectively. This study demonstrates that SGD must be considered as a significant source of nutrient input to the coastal sea area in Ariake Bay.

Language：English   Publishing type：Research paper (other academic)  

The identification of release mechanisms of arsenic may assist in designing safe and effective remediation strategies, due to its severe toxicity effect for the human body. In this regards, investigations were carried out to observe the release of As from soil into water. It was found that As concentration increased with decreasing oxidation reduction potential. Arsenic concentrations demonstrated negative covariation with the concentrations of NO₃ but strongly correlated with DOC and Fe concentrations. Batch leaching tests at different pH conditions showed a strong pH dependence on arsenic and iron leaching. A numerical simulation of arsenic transport model, coupled with microbially mediated biogeochemical processes was developed for describing the release of As in soil under reducing environment. The simulation concentrations of Mn, Fe and As were well matched those found experimentally. The results of this study suggested that the microbially mediated degradation of organic matter and reductive dissolution of Fe-oxyhydroxide are considered to be the dominant processes to release As in aquifers.

Language：English   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (other academic)  

Submarine groundwater discharge (SGD) is now recognized as an important pathway between land and sea. This study attempts to estimate the nutrient inputs through SGD to Ariake Bay. SGD rates and its quality along the coast of Ariake Bay in the Oura Region, Japan, were investigated. It was shown that the on-site SGD rate ranges from 0.01 to 20.52 μm/s, and SGD flows through the shallow confined aquifers, which consist of two kinds of rocks: basalt and pyroclastic rocks. The reduction reaction for SGD proceeded just up to denitrification. SGD associated with nutrient loads of N, P and SiO₂ were estimated to be 1.40, 0.07 and 52.78 g m^-2 d^-1, respectively. This study demonstrates that SGD must be considered as a significant source of nutrient input to the coastal sea area in Ariake Bay.

Language：English   Publishing type：Research paper (scientific journal)  

Coastal groundwater aquifers are often exposed to heavy pumping and consequently to risks of saltwater intrusion. In many cases, however, the observed increase in groundwater salinity can only be partly explained by actual saltwater intrusion from the sea. Other salinity-increasing processes may also significantly contribute to the total salt content of the groundwater. This paper describes a geochemical investigation that was carried out to investigate recent salinity increases in groundwater for the Motooka coastal area in Fukuoka, Japan. A strong increase in electrical conductivity at 15-20 m depth was observed, corresponding to the freshwater and saltwater interface. Oxidation-reduction potentials observed in deeper groundwater were low, indicating long residence time for the groundwater. These results, together with hydrogen-oxygen isotope ratio analysis, indicated that the deeper groundwater is affected by seawater. Consequently, observed tritium concentration in the shallow groundwater system was higher than that of the deeper groundwater system, and a ¹⁴C isotope dating of shell samples collected at 2 m depth indicated an age of about 2000 years. The overall results suggest that the aquifer was originally below the current sea floor and that deeper saline groundwater is not mixed with the shallower fresh groundwater. The deeper groundwater is, therefore, mainly affected by old seawater. In other words, modern saltwater intrusion has not yet occurred even if some wells contain saline water. The study shows that, even though coastal aquifers are heavily pumped, the reason for the rise in groundwater salinity may not necessarily be due to seawater intrusion. Further geochemical and hydrological investigations will be necessary to identify the underlying mechanisms.

DOI： 10.1002/hyp.6099

Language：English  

Groundwater quality is affected by the various reactions such as precipitation of dissolved ions, solid-liquid phase interaction, and the bacteriamediated reduction-oxidation process. The geochemical properties in coastal aquifers are unique and important for the management of groundwater environment. Although the studies analyzing the hydrological behaviors have been intensively done up to now, a study of coupling both groundwater flow and geochemical analysis is limited. In this study, the one-dimensional multicomponent solute transport model which accounts for the cation exchange reaction and the reduction reaction induced by anaerobic degradation is studied. It is found out both through experiment and numerical simulation that the cation exchange process is significant at the frontal part of the seawater infiltration, while reducing process by the bacteria mediation takes places at the entire soil column except for the top of the soil where dissolved oxygen infiltrates. Saltwater intrusion into a coastal aquifer is a traditional but still important for the hydro-geologists and civil engineers even at present time. Contamination of salt is a trouble for various freshwater uses. Therefore, much attention has been put on the movement and potential contamination. Meanwhile, the geophysical study is solely carried out. However, the consistent and accurate conclusion will be hardly obtained due to the complicated and limited information on the aquifer properties. In order to get a confident conclusion that can be agreed by the researchers in various fields, an interdisciplinary approach anticipating both hydrological and geochemical processes is indispensable.

DOI： 10.1142/9789812707208_0031

Language：English  

Groundwater quality is affected by the various reactions such as precipitation of dissolved ions, solid-liquid phase interaction, and the bacteriamediated reduction-oxidation process. The geochemical properties in coastal aquifers are unique and important for the management of groundwater environment. Although the studies analyzing the hydrological behaviors have been intensively done up to now, a study of coupling both groundwater flow and geochemical analysis is limited. In this study, the one-dimensional multicomponent solute transport model which accounts for the cation exchange reaction and the reduction reaction induced by anaerobic degradation is studied. It is found out both through experiment and numerical simulation that the cation exchange process is significant at the frontal part of the seawater infiltration, while reducing process by the bacteria mediation takes places at the entire soil column except for the top of the soil where dissolved oxygen infiltrates. Saltwater intrusion into a coastal aquifer is a traditional but still important for the hydro-geologists and civil engineers even at present time. Contamination of salt is a trouble for various freshwater uses. Therefore, much attention has been put on the movement and potential contamination. Meanwhile, the geophysical study is solely carried out. However, the consistent and accurate conclusion will be hardly obtained due to the complicated and limited information on the aquifer properties. In order to get a confident conclusion that can be agreed by the researchers in various fields, an interdisciplinary approach anticipating both hydrological and geochemical processes is indispensable.

DOI： 10.1142/9789812707208_0031

Language：English   Publishing type：Research paper (scientific journal)  

A multicomponent solute transport model that includes the biochemical redox reactions and cation exchange reactions was developed. It takes into consideration four different phases: pore water phase, bio phase, soil matrix phase, and solid phase. The microbially mediated sequence of reactions was modeled using Monod type equations. The model computes changes in concentration over time caused by the processes of advection, dispersion, biochemical reactions, and cation exchange reactions. A soil column experiment was conducted to determine the behavior of chemical species in aoil columns applied with secondary treated sewage water. The soil column experiment and the solute transport model had produced interesting observations on the behavior of different chemical species. The observed concentrations correlated fairly well with the simulated concentrations. The model reproduced the sequential reduction reaction. O₂ was reduced first after 30 hours then followed by NO₃^- after 31 hours. In this study, the numerical simulation of NO₃^- was done using the multicomponent solute transport model to determine the effect of pore velocity and input C H₂O concentration needed to reduce the NO₃^- leaching. It is revealed that the multicomponent solute transport model is useful to design the land, treatment system for NO₃^- removal from wastewater.

DOI： 10.1016/S0167-5648(04)80112-6

Language：English   Publishing type：Research paper (scientific journal)  

A multicomponent solute transport model that includes the biochemical redox reactions and cation exchange reactions was developed. It takes into consideration four different phases: pore water phase, bio phase, soil matrix phase, and solid phase. The microbially mediated sequence of reactions was modeled using Monod type equations. The model computes changes in concentration over time caused by the processes of advection, dispersion, biochemical reactions, and cation exchange reactions. A soil column experiment was conducted to determine the behavior of chemical species in aoil columns applied with secondary treated sewage water. The soil column experiment and the solute transport model had produced interesting observations on the behavior of different chemical species. The observed concentrations correlated fairly well with the simulated concentrations. The model reproduced the sequential reduction reaction. O₂ was reduced first after 30 hours then followed by NO₃^- after 31 hours. In this study, the numerical simulation of NO₃^- was done using the multicomponent solute transport model to determine the effect of pore velocity and input C H₂O concentration needed to reduce the NO₃^- leaching. It is revealed that the multicomponent solute transport model is useful to design the land, treatment system for NO₃^- removal from wastewater.

DOI： 10.1016/S0167-5648(04)80112-6

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

The present trend of disposing treated sewage water by allowing it to infiltrate the soil brings a new dimension to environmental problems. It is therefore necessary to identify the chemicals likely to be present in treated sewage water. A soil column experiment was conducted to determine the behavior of chemical species in soil columns applied with secondary treated sewage water. To predict the behavior of chemical species, a multicomponent solute transport model that includes the biochemical redox process and cation exchange process was developed. The model computes changes in concentration over time caused by the processes of advection, dispersion, biochemical reactions and cation exchange reactions. The solute transport model was able to predict the behavior of different chemical species in the soil column applied with secondary treated sewage water. The model reproduced the sequential reduction reaction. To design the safe depth of plow layer where NO ₃ ^- is totally reduced, a numerical study of NO ₃ ^- leach was done and it was found out that the pore velocity and concentration of CH ₂O at the inject water was found to affect NO ₃ ^- reduction in the mobile pore water phase. It is revealed that the multicomponent solute transport model is useful to design the land treatment system for NO ₃ removal from wastewater.

Language：English   Publishing type：Research paper (scientific journal)  

The present trend of disposing treated sewage water by allowing it to infiltrate the soil brings a new dimension to environmental problems. It is therefore necessary to identify the chemicals likely to be present in treated sewage water. A soil column experiment was conducted to determine the behavior of chemical species in soil columns applied with secondary treated sewage water. To predict the behavior of chemical species, a multicomponent solute transport model that includes the biochemical redox process and cation exchange process was developed. The model computes changes in concentration over time caused by the processes of advection, dispersion, biochemical reactions and cation exchange reactions. The solute transport model was able to predict the behavior of different chemical species in the soil column applied with secondary treated sewage water. The model reproduced the sequential reduction reaction. To design the safe depth of plow layer where NO ₃ ^- is totally reduced, a numerical study of NO ₃ ^- leach was done and it was found out that the pore velocity and concentration of CH ₂O at the inject water was found to affect NO ₃ ^- reduction in the mobile pore water phase. It is revealed that the multicomponent solute transport model is useful to design the land treatment system for NO ₃ removal from wastewater.

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Geochemical evaluation of distribution of heavy metals in water and sediments of Ogunpa River within Ibadan metropolis in Southwestern Nigeria is presented in respect of anthropogenic contamination from the surrounding urbanized catchment area. The results revealed low contamination or enrichment of the heavy metals (Pb, Zn, Cu, Cd, and As) in the water phase. Also, the sediment phase (<63μm) of the drainage system is anthropogenically enriched in Ph, Zn, Cu, Cd, As and t-Hg with all recording an estimated anthropogenic factor (AF) value above 1. The estimated index of geoaccumulation (I_gco) with a value of approximately 2 for Pb, Zn and t-Hg indicates moderate or middle level contamination in the sediments while I_gco of <1 recorded for Cu, Cd, and As indicate very low or no contamination. This trend is however, reversed in the water column with Cu and Cd having I_gco value of 1.2 and 3.2 respectively, pointing to relative partitioning of the metals between the two media. Quantification of degree of pollution revealed high anthropogenic contribution for Pb (75%), Zn (75%) and t-Hg (60%), indicating enrichment by a factor of at least 5 in the sediment phase, while anthropogenic in-put also accounts for 70% (Cu) and 90% (Cd) in the water column. Furthermore, correlation of electrical conductivity (EC) peaks with the high values of Pb, Zn and t-Hg indicated that the inputs are related to anthropogenic sources along the stretches of the Ogunpa channel. The sources of contamination are attributed to urbanised anthropogenic sources, mostly vehicular emissions and related repair products, domestic sewage and effluents, varied household garbages and refuse dumps including incineration bye-products. Based on the overall evaluation, recommendations in respect of sanitization and contamination control/monitoring strategies in the study area are also presented.

DOI： 10.4314/jmg.v40i1.18811

Language：English   Publishing type：Research paper (scientific journal)  

Geochemical evaluation of distribution of heavy metals in water and sediments of Ogunpa River within Ibadan metropolis in Southwestern Nigeria is presented in respect of anthropogenic contamination from the surrounding urbanized catchment area. The results revealed low contamination or enrichment of the heavy metals (Pb, Zn, Cu, Cd, and As) in the water phase. Also, the sediment phase (<63μm) of the drainage system is anthropogenically enriched in Ph, Zn, Cu, Cd, As and t-Hg with all recording an estimated anthropogenic factor (AF) value above 1. The estimated index of geoaccumulation (I_gco) with a value of approximately 2 for Pb, Zn and t-Hg indicates moderate or middle level contamination in the sediments while I_gco of <1 recorded for Cu, Cd, and As indicate very low or no contamination. This trend is however, reversed in the water column with Cu and Cd having I_gco value of 1.2 and 3.2 respectively, pointing to relative partitioning of the metals between the two media. Quantification of degree of pollution revealed high anthropogenic contribution for Pb (75%), Zn (75%) and t-Hg (60%), indicating enrichment by a factor of at least 5 in the sediment phase, while anthropogenic in-put also accounts for 70% (Cu) and 90% (Cd) in the water column. Furthermore, correlation of electrical conductivity (EC) peaks with the high values of Pb, Zn and t-Hg indicated that the inputs are related to anthropogenic sources along the stretches of the Ogunpa channel. The sources of contamination are attributed to urbanised anthropogenic sources, mostly vehicular emissions and related repair products, domestic sewage and effluents, varied household garbages and refuse dumps including incineration bye-products. Based on the overall evaluation, recommendations in respect of sanitization and contamination control/monitoring strategies in the study area are also presented.

DOI： 10.4314/jmg.v40i1.18811

Language：English   Publishing type：Research paper (scientific journal)  

Due to uncertainties raised about the presence of contaminants from recycled water it is necessary to identify the chemicals likely to be present in treated sewage water, and assess approaches for minimizing their release. The relevant physical, chemical and biochemical processes must be understood in order to determine the state and movement of contaminants. To simulate the mechanisms responsible for the movement of chemical species, predictive tools in the form of mathematical models have been developed. This study deals with the processes and chemical transport in an aqueous soil similar to paddy fields where successive reduction reactions occur. To examine the behaviour of the different chemical species present in the secondary treated sewage water, a two-soil column experiment was conducted. In order to more fully understand chemical and biochemical processes, a solute transport model that takes into consideration the biochemical reactions and cation exchange reactions was developed in this study. The soil column experiment and the solute transport model produced interesting observations on the behaviour of different chemical species. The observed concentrations correlated fairly well with the simulated concentrations and the sequence of reduction reactions were reproduced by the developed solute transport model.

Language：English   Publishing type：Research paper (scientific journal)  

Due to uncertainties raised about the presence of contaminants from recycled water it is necessary to identify the chemicals likely to be present in treated sewage water, and assess approaches for minimizing their release. The relevant physical, chemical and biochemical processes must be understood in order to determine the state and movement of contaminants. To simulate the mechanisms responsible for the movement of chemical species, predictive tools in the form of mathematical models have been developed. This study deals with the processes and chemical transport in an aqueous soil similar to paddy fields where successive reduction reactions occur. To examine the behaviour of the different chemical species present in the secondary treated sewage water, a two-soil column experiment was conducted. In order to more fully understand chemical and biochemical processes, a solute transport model that takes into consideration the biochemical reactions and cation exchange reactions was developed in this study. The soil column experiment and the solute transport model produced interesting observations on the behaviour of different chemical species. The observed concentrations correlated fairly well with the simulated concentrations and the sequence of reduction reactions were reproduced by the developed solute transport model.

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

In order to clarify the behaviour of chemical species under reducing condition in a subaqueous soil similar to a paddy field, a column experiment was carried out. As Mn- and Fe-(hydr)oxides were dissolved by microbially mediated reduction, Na⁺, K⁺, Mg²⁺, Ca²⁺, Mn²⁺, and Fe²⁺ existed in the pore water as major cations. The Ca²⁺ concentration had a tendency to decrease in the layer at 5-25 cm depth in the column, whereas the Ca²⁺ concentration increased with time below 45 cm depth. This phenomenon can be assumed to be due to the desorption of Ca²⁺, by Mn²⁺ and Fe²⁺, and its infiltration. Therefore, it is necessary to develop a solute transport model which takes into account both biochemical and cation exchange reactions. In this paper, a simulation model that considers both reactions is described and applied to simulate the results of the column experiment. The reliability of this model was evaluated by comparing the calculated results with the result of the experiment.

Language：English   Publishing type：Research paper (scientific journal)  

In order to clarify the behaviour of chemical species under reducing condition in a subaqueous soil similar to a paddy field, a column experiment was carried out. As Mn- and Fe-(hydr)oxides were dissolved by microbially mediated reduction, Na⁺, K⁺, Mg²⁺, Ca²⁺, Mn²⁺, and Fe²⁺ existed in the pore water as major cations. The Ca²⁺ concentration had a tendency to decrease in the layer at 5-25 cm depth in the column, whereas the Ca²⁺ concentration increased with time below 45 cm depth. This phenomenon can be assumed to be due to the desorption of Ca²⁺, by Mn²⁺ and Fe²⁺, and its infiltration. Therefore, it is necessary to develop a solute transport model which takes into account both biochemical and cation exchange reactions. In this paper, a simulation model that considers both reactions is described and applied to simulate the results of the column experiment. The reliability of this model was evaluated by comparing the calculated results with the result of the experiment.

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

This paper presents a numerical model for predicting solute transport with multicomponent chemical reactions in subsurface. A nonlinear least-squares estimation by the Levenberg-Marquardt method is adopted for obtaining numerical solution of the chemical reaction term in the advection-dispersion equations. To test the reliability of the model, a laboratory experiment is performed with continuous injection of KCl solution into an undisturbed soil column. The values of cation exchange capacity of the soil used in the experiment have spatial distribution with a range from 15 meq/100g in the upper part of the column to 5 meq/100g in the lower part. Based on the numerical and experimental results, the effect of the choice of selectivity coefficient on the cation concentrations is investigated. When the exponential function with respect to the equivalent fraction of K⁺ on sorption site is employed for selectivity coefficient between Ca²⁺ and K⁺, the calculated results by the model developed here are in good agreement with the measured vertical distributions of the cation concentrations in solution and sorption sites. The use of fixed selectivity coefficient results in poor prediction accuracy. It is concluded that the accuracy of model predictions can be improved by suitable choice of selectivity coefficient for the soil being considered.

Language：English   Publishing type：Research paper (scientific journal)  

This paper presents a numerical model for predicting solute transport with multicomponent chemical reactions in subsurface. A nonlinear least-squares estimation by the Levenberg-Marquardt method is adopted for obtaining numerical solution of the chemical reaction term in the advection-dispersion equations. To test the reliability of the model, a laboratory experiment is performed with continuous injection of KCl solution into an undisturbed soil column. The values of cation exchange capacity of the soil used in the experiment have spatial distribution with a range from 15 meq/100g in the upper part of the column to 5 meq/100g in the lower part. Based on the numerical and experimental results, the effect of the choice of selectivity coefficient on the cation concentrations is investigated. When the exponential function with respect to the equivalent fraction of K⁺ on sorption site is employed for selectivity coefficient between Ca²⁺ and K⁺, the calculated results by the model developed here are in good agreement with the measured vertical distributions of the cation concentrations in solution and sorption sites. The use of fixed selectivity coefficient results in poor prediction accuracy. It is concluded that the accuracy of model predictions can be improved by suitable choice of selectivity coefficient for the soil being considered.

Language：Japanese   Book type：Scholarly book

Language：Japanese   Book type：General book, introductory book for general audience

Language：Japanese   Book type：General book, introductory book for general audience

Responsible for pages：251-260   Language：English  

Groundwater quality is affected by the various reactions such as precipitation of dissolved ions, solid-liquid phase interaction, and the bacteriamediated reduction-oxidation process. The geochemical properties in coastal aquifers are unique and important for the management of groundwater environment. Although the studies analyzing the hydrological behaviors have been intensively done up to now, a study of coupling both groundwater flow and geochemical analysis is limited. In this study, the one-dimensional multicomponent solute transport model which accounts for the cation exchange reaction and the reduction reaction induced by anaerobic degradation is studied. It is found out both through experiment and numerical simulation that the cation exchange process is significant at the frontal part of the seawater infiltration, while reducing process by the bacteria mediation takes places at the entire soil column except for the top of the soil where dissolved oxygen infiltrates. Saltwater intrusion into a coastal aquifer is a traditional but still important for the hydro-geologists and civil engineers even at present time. Contamination of salt is a trouble for various freshwater uses. Therefore, much attention has been put on the movement and potential contamination. Meanwhile, the geophysical study is solely carried out. However, the consistent and accurate conclusion will be hardly obtained due to the complicated and limited information on the aquifer properties. In order to get a confident conclusion that can be agreed by the researchers in various fields, an interdisciplinary approach anticipating both hydrological and geochemical processes is indispensable.

DOI： 10.1142/9789812707208_0031

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学   Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：山梨大学   Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.3 - 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：佐賀大学   Country：Japan  

Event date： 2017.3

Language：Japanese  

Venue：佐賀大学   Country：Japan  

Event date： 2016.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Japan   Country：Japan  

Imazu Bay plays an important role for endangered species such as horseshoe crabs and black-faced spoonbills that stay in the bay for spawning or passing the winter. However, this bay is semi-enclosed with slow water exchange, which could lead to eutrophication under the condition of excess nutrient inflow to the bay. Therefore, quantification of nutrient inflow is of great importance. Generally, analysis of nutrient inflow to bays takes into consideration nutrient inflow from only river, but that from groundwater should not be ignored for more accurate results.
The main objective of this study is to estimate amounts of nutrient inflow from river and groundwater to Imazu Bay by analyzing water budget in Zuibaiji River Basin and loads of T-N, T-P, NO3-N and NH4-N. The water budget computation in the basin is performed using groundwater recharge model and quasi three-dimensional two-phase groundwater flow model, and the multiplication of the measured amount of nutrient inflow with the computed discharge gives the total amount of nutrient inflow to the bay. In addition, in order to evaluate nutrient inflow to the bay, the result is compared with nutrient inflow from geologically similar river basins.
The result shows that the discharge is 3.50×107 m3/year from the river and 1.04×107 m3/year from groundwater. The submarine groundwater discharge accounts for approximately 23% of the total discharge, which is large compared to the other river basins. It is also revealed that the total nutrient inflow is not particularly large. The sum of NO3-N and NH4-N loadings from groundwater is less than 10% of that from the river because of denitrification in groundwater. Shin Seibu Sewage Treatment Plant located below the observation points discharges treated water of 15,400 m3/day and plans to increase it. However, the loads of T-N and T-P from the treatment plant are 3.9 mg/L and 0.19 mg/L, so that it does not contribute a lot to eutrophication.

Event date： 2015.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井県大野市   Country：Japan  

Event date： 2015.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2015.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2015.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：琉球大学   Country：Japan  

Event date： 2014.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2014.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2013.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：秋田県秋田市   Country：Japan  

Event date： 2013.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：秋田県秋田市   Country：Japan  

Event date： 2013.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本大学   Country：Japan  

Event date： 2013.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：熊本大学   Country：Japan  

Event date： 2012.3

Country：Japan  

Event date： 2011.3

Country：Japan  

Event date： 2011.3

Country：Japan  

Event date： 2010.3 - 2010.5

Venue：熊本県   Country：Japan  

Event date： 2010.3

Venue：熊本県   Country：Japan  

Event date： 2010.3

Venue：熊本県   Country：Japan  

Event date： 2009.9

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2008.3

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Event date： 2008.3

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Event date： 2008.3

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Event date： 2008.3

Presentation type：Oral presentation (general)  

Venue：長崎   Country：Japan  

Event date： 2007.12

Presentation type：Oral presentation (general)  

Venue：Fremantle   Country：Australia  

Event date： 2007.11

Presentation type：Oral presentation (general)  

Venue：長野   Country：Japan  

Event date： 2007.11

Presentation type：Oral presentation (general)  

Venue：長野   Country：Japan  

Event date： 2007.11

Presentation type：Oral presentation (general)  

Venue：長野   Country：Japan  

Event date： 2007.10

Presentation type：Oral presentation (general)  

Venue：Ontario   Country：Canada  

Event date： 2007.9

Presentation type：Oral presentation (general)  

Venue：Lisbon   Country：Portugal  

Event date： 2007.6

Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2007.5

Presentation type：Oral presentation (general)  

Venue：千葉県   Country：Japan  

Event date： 2007.5

Presentation type：Oral presentation (general)  

Venue：千葉県   Country：Japan  

Event date： 2007.5

Presentation type：Oral presentation (general)  

Venue：千葉県   Country：Japan  

Event date： 2007.5

Presentation type：Oral presentation (general)  

Venue：千葉県   Country：Japan  

Event date： 2007.4

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州産業大学（福岡市）   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州産業大学（福岡市）   Country：Japan  

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州産業大学（福岡市）   Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Symposium, workshop panel (public)  

Venue：京都大学   Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2019.10

Language：Japanese   Presentation type：Symposium, workshop panel (public)  

Venue：大阪市   Country：Japan  

Event date： 2018.6 - 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2018.2

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2017.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2009.7

Language：English  

Venue：Cairns   Country：Australia  

Over-exploitation of groundwater in coastal aquifers is one of the major reasons for saltwater intrusion. Saltwater intrusion contaminates the freshwater resource in coastal aquifers by increasing the salinity levels of the groundwater. A small quantity of saltwater is enough to contaminate the large quantity of freshwater in a coastal aquifer. Therefore, saltwater intrusion should be considered seriously. Numerical models are needed to enhance the understanding of saltwater intrusion and its related phenomena extensively. The Motooka region in the Fukuoka prefecture in Japan is a coastal area, where groundwater is the main water resource for green house agriculture and domestic use. Over-exploitation of groundwater in this coastal region has resulted in saltwater intrusion and thus in the contamination of the freshwater aquifer. In addition to the more obvious effects of saltwater intrusion, fluctuations in salinity caused by such intrusion is a crucial problem to address, since even slight changes in salinity of the water use for agricultural purposes significantly affect the crop's growth and yield. So far, a research on the salinity fluctuations with groundwater pumping and their effects on seasonal recharge of groundwater in the Motooka region has not been conducted. Therefore, in this study a three-dimensional density-dependent solute transport flow model is developed to simulate the salinity fluctuations due to groundwater pumping. In the present numerical study, the emphasis is on the development of conceptual, mathematical and numerical model of variable density flow and solute transport and its application to simulate the salinity fluctuation due to groundwater pumping at different rates. The model is based on the “transition zone” approach, which considers the interface as a miscible zone where freshwater and saltwater is mixing while maintaining a density gradient across the freshwater/saltwater interface. The transition zone approach requires simultaneous solutions of the governing water flow and solute transport equations. To this end, the model incorporates three fundamental equations in flow and solute transport, namely Darcy's law, general groundwater flow equation and the advection dispersion solute transport equation. The groundwater flow equation and solute transport equation are coupled by the equation of state to produce the salt concentration at each time step for whole flow domain. The finite difference method is used as the numerical technique to solve the partial differential equations of flow and transport under an implicit scheme. The method of characteristics is applied to solve the advection term in the solute transport equation. A non-uniform discretized grid system is adopted in the flow domain allocating relatively small grid sizes to pumping well locations. To achieve reliable results, relevant and important hydro-geological parameters are assigned to the numerical model after considering the hydrological situation of the Motooka region. Different boundary conditions are assigned considering the dominant hydrological processes those are believed to be in effect in the selected area. The numerical results obtained from the model demonstrate the salinity variation due to groundwater pumping and seasonal recharge rates from year 2001 to 2007 under the influence of saltwater intrusion. The results also reveal that model is capable of correctly simulating the physical processes. A comparison of the measured and modeled electric conductivities shows reasonable agreement.

Event date： 2009.7

Language：English  

Venue：Cairns, QLD   Country：Australia  

Over-exploitation of groundwater in coastal aquifers is one of the major reasons for saltwater intrusion. Saltwater intrusion contaminates the freshwater resource in coastal aquifers by increasing the salinity levels of the groundwater. A small quantity of saltwater is enough to contaminate the large quantity of freshwater in a coastal aquifer. Therefore, saltwater intrusion should be considered seriously. Numerical models are needed to enhance the understanding of saltwater intrusion and its related phenomena extensively. The Motooka region in the Fukuoka prefecture in Japan is a coastal area, where groundwater is the main water resource for green house agriculture and domestic use. Over-exploitation of groundwater in this coastal region has resulted in saltwater intrusion and thus in the contamination of the freshwater aquifer. In addition to the more obvious effects of saltwater intrusion, fluctuations in salinity caused by such intrusion is a crucial problem to address, since even slight changes in salinity of the water use for agricultural purposes significantly affect the crop's growth and yield. So far, a research on the salinity fluctuations with groundwater pumping and their effects on seasonal recharge of groundwater in the Motooka region has not been conducted. Therefore, in this study a three-dimensional density-dependent solute transport flow model is developed to simulate the salinity fluctuations due to groundwater pumping. In the present numerical study, the emphasis is on the development of conceptual, mathematical and numerical model of variable density flow and solute transport and its application to simulate the salinity fluctuation due to groundwater pumping at different rates. The model is based on the "transition zone"approach, which considers the interface as a miscible zone where freshwater and saltwater is mixing while maintaining a density gradient across the freshwater/saltwater interface. The transition zone approach requires simultaneous solutions of the governing water flow and solute transport equations. To this end, the model incorporates three fundamental equations in flow and solute transport, namely Darcy's law, general groundwater flow equation and the advection dispersion solute transport equation. The groundwater flow equation and solute transport equation are coupled by the equation of state to produce the salt concentration at each time step for whole flow domain. The finite difference method is used as the numerical technique to solve the partial differential equations of flow and transport under an implicit scheme. The method of characteristics is applied to solve the advection term in the solute transport equation. A non-uniform discretized grid system is adopted in the flow domain allocating relatively small grid sizes to pumping well locations. To achieve reliable results, relevant and important hydro-geological parameters are assigned to the numerical model after considering the hydrological situation of the Motooka region. Different boundary conditions are assigned considering the dominant hydrological processes those are believed to be in effect in the selected area. The numerical results obtained from the model demonstrate the salinity variation due to groundwater pumping and seasonal recharge rates from year 2001 to 2007 under the influence of saltwater intrusion. The results also reveal that model is capable of correctly simulating the physical processes. A comparison of the measured and modeled electric conductivities shows reasonable agreement.

Event date： 2008.10

Language：English  

Venue：Kyoto   Country：Japan  

The Motooka region in Fukuoka, Japan is a coastal region where agriculture is dominant. The green houses and wineries cover their water demand from groundwater. With the increased water demand, seawater intrusion is identified as an alarming threat to the Motooka coastal aquifer in near future. The measured electric conductivities of the water samples have been analyzed periodically. Until now the measured electric conductivities do not show high values but those values convince the emerging threat of seawater intrusion in this aquifer in future if groundwater will be pumped at current rate further. Therefore it is worth to conduct a numerical study of seawater intrusion and its impact to the Motooka area since the sustainability of the aquifer is inevitable for the future groundwater development and agriculture. In this paper a numerical study of the seawater intrusion of the Motooka is discussed. The numerical model presented in this paper was developed by coupling the groundwater flow equation with the mass transport equation to simulate the density dependent solute transport in the three dimensional space. The usage of this model as a management tool to simulate the salinity variation with groundwater pumping is emphasized. The numerical model was adequately capable of simulating the seawater intrusion and numerical results show a satisfactory agreement with the field observations.

Event date： 2008.10

Language：English  

Venue：Kyoto   Country：Japan  

Groundwater discharge to sea areas affects environmental conditions along coasts. Enclosed bays may experience eutrophication caused by nutrient input from land areas through groundwater discharge since groundwater is often contaminated by large amounts of nutrients as compared with river water. Therefore, it is necessary to estimate the groundwater discharge into seas quantitatively in order to understand nutrient pathways. A distributed groundwater recharge model was developed in order to estimate total groundwater discharge flow into the Ariake Bay, in Kyushu, Japan. The Komoda catchment within the Kikuchi River basin in Kumamoto prefecture was studied as a representative area for the Ariake Bay. The model partitions rainfall into direct runoff, evapotranspiration, and groundwater recharge. Parameters are set based on land use. Groundwater discharge is calculated using a water balance approach. The results show that groundwater discharge into the Ariake Bay from Kukuchi River basin is on average 123 mm year^-1. The groundwater discharge accounts for about 8% of total water discharge and 9% of river discharge. The results can be used to better estimate annual transport of nutrients in the groundwater to the sea and thus also to better manage eutrophication problems.

Event date： 2007.12

Language：English  

Venue：Christchurch   Country：New Zealand  

Event date： 2007.10

Language：English  

Venue：Amherst, MA   Country：United States  

The identification of release mechanisms of arsenic may assist in designing safe and effective remediation strategies, due to its severe toxicity effect for the human body. In this regards, investigations were carried out to observe the release of As from soil into water. It was found that As concentration increased with decreasing oxidation reduction potential. Arsenic concentrations demonstrated negative covariation with the concentrations of NO₃ but strongly correlated with DOC and Fe concentrations. Batch leaching tests at different pH conditions showed a strong pH dependence on arsenic and iron leaching. A numerical simulation of arsenic transport model, coupled with microbially mediated biogeochemical processes was developed for describing the release of As in soil under reducing environment. The simulation concentrations of Mn, Fe and As were well matched those found experimentally. The results of this study suggested that the microbially mediated degradation of organic matter and reductive dissolution of Fe-oxyhydroxide are considered to be the dominant processes to release As in aquifers.

Event date： 2007.9

Language：English  

Venue：Copenhagen   Country：Denmark  

Oxidation-reduction geochemical processes coupled with mass transport in a coastal aquifer is a unique subsurface environmental phenomenon to model. When a porous material is contaminated by organic carbons, nitrate is denitrified and manganese dioxide and oxi-iron hydroxide would be reduced. However, it is expected that the reduced divalent iron is oxidized once again by seawater when discharged to the sea. The paper discusses a numerical model of transport and geochemical reaction processes along the mixing zone of fresh and reduced salt water in a coastal aquifer. By comparing the numerical solution with experimental observations for the precipitation of divalent iron along the mixing zone, the validity of the model is demonstrated.

Event date： 2007.7

Presentation type：Oral presentation (general)  

Venue：Venice   Country：Italy  

Event date： 2007.7

Language：English  

Venue：Perugia   Country：Italy  

Submarine groundwater discharge (SGD) is now recognized as an important pathway between land and sea. This study attempts to estimate the nutrient inputs through SGD to Ariake Bay. SGD rates and its quality along the coast of Ariake Bay in the Oura Region, Japan, were investigated. It was shown that the on-site SGD rate ranges from 0.01 to 20.52 μm/s, and SGD flows through the shallow confined aquifers, which consist of two kinds of rocks: basalt and pyroclastic rocks. The reduction reaction for SGD proceeded just up to denitrification. SGD associated with nutrient loads of N, P and SiO₂ were estimated to be 1.40, 0.07 and 52.78 g m^-2 d^-1, respectively. This study demonstrates that SGD must be considered as a significant source of nutrient input to the coastal sea area in Ariake Bay.

Event date： 2007.4

Venue：福岡市   Country：Japan  

Event date： 1999.9

Language：English  

Venue：Zurich, Switz   Country：Other  

In order to clarify the behaviour of chemical species under reducing condition in a subaqueous soil similar to a paddy field, a column experiment was carried out. As Mn- and Fe-(hydr)oxides were dissolved by microbially mediated reduction, Na⁺, K⁺, Mg²⁺, Ca²⁺, Mn²⁺, and Fe²⁺ existed in the pore water as major cations. The Ca²⁺ concentration had a tendency to decrease in the layer at 5-25 cm depth in the column, whereas the Ca²⁺ concentration increased with time below 45 cm depth. This phenomenon can be assumed to be due to the desorption of Ca²⁺, by Mn²⁺ and Fe²⁺, and its infiltration. Therefore, it is necessary to develop a solute transport model which takes into account both biochemical and cation exchange reactions. In this paper, a simulation model that considers both reactions is described and applied to simulate the results of the column experiment. The reliability of this model was evaluated by comparing the calculated results with the result of the experiment.

Presentation type：Symposium, workshop panel (public)  

Venue：京都大学   Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：LISBON   Country：Portugal  

Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Presentation type：Oral presentation (general)  

Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：京都   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：大分   Country：Japan  

Presentation type：Oral presentation (general)  

Venue：大分   Country：Japan  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

Language：Japanese  

Language：Japanese  

Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

Language：Japanese   Publishing type：Internal/External technical report, pre-print, etc.  

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：1

Type：Competition, symposium, etc. 

Number of participants：3,000

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：1

Number of peer-reviewed articles in Japanese journals：4

Type：Competition, symposium, etc. 

Number of participants：3,000

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：8,000

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Number of participants：8,000

Type：Competition, symposium, etc. 

Number of participants：150

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

・平成29年度　水・土壌環境保全活動功労者賞
平成29年度「水・土壌環境保全活動功労者」表彰を受賞。この賞は水・土壌環境の保全に関し顕著な功績のあった団体や個人に対し、その功績を讃えるため、環境省水・大気環境局長から表彰状が授与された。

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Seminar, workshop

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Research consultation

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Seminar, workshop

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：Infants,　Schoolchildren,　Junior students,　High school students

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Seminar, workshop

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Lecture

Audience：General,　Scientific,　Company,　Civic organization,　Governmental agency

Type：Other

「大学専用水道と地域農業用水供給の可能性調査」として、大学への経済的な上水道供給と、大学移転周辺地区の塩水化が万一進行した場合の地域への農業用水確保を両立する目的で、地元との合意形成実現に向けて技術的問題の研究成果を報告するものである。

対談
佐藤耕三・大分市上下水道事業管理者
広城吉成・九州大学大学院准教授
着実に管路更新・耐震化を進める大分市水道事業

老朽化した水道管の更新をどう進めるべきか。水道インフラに詳しい九州大学大学院の広城吉成准教授に聞いた。

上下水道のカーボンニュートラルに向けた提言

計画部門（各種データ解析、公民連携、アセットマネジメント、その他）に関する水道研究発表において「発表論文の聞きどころ」について（2019年（令和元年）10月24日）第5365号