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Yoshinari HIROSHIRO Last modified date:2021.11.15

Associate Professor / Water and Material Cycles System
Faculty of Engineering


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Homepage
https://kyushu-u.pure.elsevier.com/en/persons/yoshinari-hiroshiro
 Reseacher Profiling Tool Kyushu University Pure
http://www.doc.kyushu-u.ac.jp/
Phone
092-802-3430
Fax
092-802-3430
Academic Degree
Doctor of Engineering
Country of degree conferring institution (Overseas)
Yes
Field of Specialization
Groundwater Environmental Systems, Water Supply Engineering, Water Resources Engineering
Total Priod of education and research career in the foreign country
00years03months
Research
Research Interests
  • Investigating Effect of Pumping Ratio on Effectiveness of Barrier Wells for Saltwater Intrusion: Lab-Scale Experiments and Numerical Modeling
    keyword : Global warming, Rising of seawater level, Saline-affected groundwater, Fresh-groundwater, Exploitation of groundwater
    2019.04~2023.03.
  • Transport properties of Fluoride and Boron in groundwater
    keyword : fluoride, Boron, Granite, Decomposed Granite Soil
    2020.04~2022.03.
  • Interaction analysis between river water and groundwater is important on behalf of sound hydrological cycle and its management.
    keyword : Interaction analysis between river water and groundwater, Development of sound hydrological cycle
    2015.04.
  • Scaling up of groundwater flow and geochemical transport to Ariake Bay
    keyword : Submarine groundwater discharge, Groundwater recharge, Hydrological model, Water budget analysis, Quasi-three dimensional groundwater flow model
    2005.04.
  • Practical of sound hydrological cycle in region (Itoshima area)
    keyword : Groundwater-surface water interaction, Groundwater flow model, Tracer, groundwater recharge model, affected-saline groundwater
    2001.01.
  • Study on hydrogeochemical properties of a salinity-affected coastal aquifer.
    keyword : Salinity-affected coastal groundwater aquifer,Groundwater quality,Redox condition, Electrical conductivity
    2002.04.
  • Breakthrough of arsenic behavior and development of arsenic removal system in groundwater
    keyword : Arsenic, Fe–Mn oxyhydroxides, Groundwater contamination , Organic matter, Biologically mediated redox processes
    2006.10~2022.03.
Academic Activities
Books
1. Geochemistry, Groundwater and Pollution, 2nd edition.
2. Geochemistry, Groundwater and Pollution, 2nd edition.
3. Yoshinari HIROSHIRO, Kei NAKAGAWA, Kenji JINNO, Handbook of Applied Hydrology, Second Edition, McGraw Hill Education, Chapter 69 Pollutant Transport in Groundwater, 2016.10, Groundwater has several special features. Among them mild temperature variation with depth, its unique taste influenced by the dissolved minerals and less seasonal variation in yield compared to surface water, are significant. Those features make the groundwater as an important source of water for drinking, agriculture and industry. Industrialization, rapid economic growths in countries, global population increase and intensive agriculture have seriously influenced on the sustainability of groundwater resources around the world. Extensive application of agro-chemicals, petroleum products, landfills, septic tanks and various underground waste storages are considered as the potential man-made contaminants when they leak into the groundwater while the natural deposits of poisonous minerals including heavy metals such as arsenic and cadmium are also seriously affecting the quality of subsurface water quality. Although most of the natural toxic deposits are not hazardous until they remain in their natural repositories, the disturbances caused by mining, tunnel excavations and underground developments increase the risk of contamination of groundwater by exposing the groundwater to make contacts which aforementioned materials. Remediation of contaminant groundwater is costly and a highly advanced technology is sought if the contamination has caused by toxic elements such as heavy metals, nuclear wastes and human wastes. Leakages of toxic organic and inorganic components from storages, natural and man-made accidents cause groundwater hazards. Engineered ground water remediation technologies have emerged in recent years to recover the polluted groundwater and protect the existing aquifers from possible contaminants. Not only the technological advances, but also proper groundwater regulations and policies are essential to maintain a sustainable groundwater environment for industrial, agricultural and domestic requirements. In order to conserve the groundwater environment, sound understanding of the flow and transport of contaminants in subsurface environment is inevitable. This chapter presents the mechanics of groundwater and solute transport exposing several examples to enhance the understating aforementioned phenomenon..
Papers
1. Shinichi Ozaki, Christel Abi Akl, Tatsuya Nagino, Yoshinari Hiroshiro, Investigating Effect of Pumping Ratio on Effectiveness of Barrier Wells for Saltwater Intrusion: Lab-Scale Experiments and Numerical Modeling, Water, 10.3390/w13152100, Vol.13(Issue15), 2100, Water, Vol.13(Issue15), 2100; DOI:10.3390/w13152100, 2021.07, [URL], Saltwater intrusion, leading to the salinization of fresh groundwater, is the most challenging problem in coastal regions. Saltwater pumping from a barrier well is widely applied to prevent saltwater intrusion. Owing to its easy installation, many studies have investigated saltwater pumping. However, quantitative relationships between the barrier and inland production wells have not been revealed. In this study, lab-scale experiments were conducted to examine the effectiveness of a barrier well on the possible flow rate of freshwater from a production well. Moreover, a two-dimensional numerical model was created and simulated under the same conditions as those used in the experiments to analyze the experimental results. Consequently, a critical pumping ratio of 1.9 was obtained. In the numerical simulation, it was confirmed that an upconing of highly concentrated saltwater toward the barrier well was observed when the pumping ratio was less than the critical ratio. In conclusion, there is a critical pumping ratio between the barrier and the production well, and saltwater intrusion can be controlled by keeping the pumping rates under the critical ratio. Although further studies have yet to be conducted on a practical scale, this study showed the potential of the pumping ratio control to manage saltwater intrusion.
Keywords: salinity-affected coastal aquifer; saltwater intrusion; barrier well; production well; critical groundwater pumping ratio; laboratory experiment; global warming; sandy aquifer.
2. Yoshinari HIROSHIRO, Masataka MATSUMOTO, Akihiko KINOSHITA, Atushi TSUTSUMI, Hydrological Analysis of Interaction between Surface and Subsurface Water in the Middle Basin of the Obaru River, Western Fukuoka, Japan, International Symposium on Earth Science and Technology 2017, 2017.11, 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..
3. Yoshinari HIROSHIRO, Keisuke KONISHI, Kento TERASHIMA, Atsushi TSUTSUMI, Two Different Modeling Approaches for Quantitative Analysis of Nutrient Input from River and Groundwater to Imazu Bay in Fukuoka, Japan, Proceedings of International Symposium on Earth Science and Technology 2016, 394-397, 394-397, 2016.12.
4. Yoshinari HIROSHIRO, Keisuke KONISHI, Estimation of amount of groundwater pumping discharge and its effect on salinization of groundwater around Ito Campus, Kyushu University, MEMOIRS OF THE FACULTY OF ENGINEERING KYUSHU UNIVERSITY, Vol.76, No.1, 2016.07, 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..
5. Yoshinari HIROSHIRO, Keisuke Konishi, Kento Terashima, Atushi Tsutsumi, Quantive Analysis of Nutrient Inflow from River and Groundwater to Imazu Bay in Fukuoka, Japan, 18th International Conference on Environment and Water Resource Management, 3320-3325, 2016.05.
6. TWO-DIMENSIONAL TRANSPORT MODEL OF ARSENIC CONSIDERING THE REDOX REACTION IN GROUNDWATER.
7. M.A. Halim, R.K. Majumder, S.A. Nessa, Y. Hiroshiro, K. Sasaki, B.B. Saha, A. Saepuloh and K. Jinno, Evaluation of processes controlling the geochemical constituents in deep groundwater in Bangladesh: spatial variability on arsenic and boron enrichment, Journal of Hazardous Materials, 10.1016/j.jhazmat.2010.01.008, Vol.180, 50-62, 2010.10.
8. Shiguo XU, Changwu YU, Yoshinari Hiroshiro, Migration behavior of Fe, Cu, Zn, and Mo in alkaline tailings from Lanjiagou porphyry molybdenum deposits, Northern China, MEMOIRS OF THE FACULTY OF ENGINEERING KYUSHU UNIVERSITY, Vol.70, No.2, 2010.06.
9. Shiguo XU, Yong DING, Kenji Jinno, Wenyi LI, Yoshinari Hiroshiro , Feasibility and Quantification Analysis of Floodwater Utilization, MEMOIRS OF THE FACULTY OF ENGINEERING KYUSHU UNIVERSITY, Vol.70, No.1, 2010.03.
10. Md Abdul Halim, Ratan K. Majumder, Syeda Afsarun Nessa, Keita Oda, Yoshinari Hiroshiro, Kenji Jinno, Arsenic in shallow aquifer in the eastern region of Bangladesh
Insights from principal component analysis of groundwater compositions, Environmental Monitoring and Assessment, 10.1007/s10661-009-0760-9, 161, 1-4, 453-472, 2010.02, 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..
11. M.A. Halim, R.K. Majumder, S.A. Nessa, Y. Hiroshiro, K. Sasaki, B.B. Saha, A. Saepuloh and K. Jinno , Evaluation of processes controlling the geochemical constituents in deep groundwater in Bangladesh: spatial variability on arsenic and boron enrichment
, Journal of Hazardous Materials, 10.1016/j.jhazmat.2010.01.008, 2010.01.
12. E.D.P. Perera, Kenji Jinno,Yoshinari Hiroshiro , Bacteria-mediated Reduction and Precipitation of Fe(OH)3 and FeS in the Subsurface of a Coastal Aquifer: A Numerical Investigation, Water Quality, Exposure and Health, Springer, 10.1007/s12403-009-0021-8, 2010.01.
13. Md. Abdul HALIM, Ratan K. MAJUMDER, Keita ODA, Yoshinari Hiroshiro, Keiko SASAKI and Kenji JINNO, Assessment of Processes Controlling the Geochemical Constituents in Deep Groundwater of Bangladesh with Spatial Variability on Arsenic and Boron Enrichment, International Symposium on Earth Science and Technology 2009, 167-170, 2009.12.
14. Groundwater - surface water interaction analysis using a groundwater flow model and radioactive isotopes
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15. M. A. Halim, R. K. Majumder, S. A. Nessa, Y. Hiroshiro, M. J. Uddin, J. Shimada, K. Jinno, Hydrogeochemistry and arsenic contamination of groundwater in the Ganges Delta Plain, Bangladesh, Journal of Hazardous Materials, 10.1016/j.jhazmat.2008.09.046, 164, 2-3, 1335-1345, 2009.05, 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 SO42-, and high concentrations of dissolved organic carbon (DOC), HCO3- and PO43- 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 SO42- demonstrates the As may not be directly mobilized from sulfide minerals like arsenopyrite..
16. Md. Abdul Halim, Ratan K. Majumder, Syeda Afsarun Nessa, Keita Oda, Yoshinari Hiroshiro, Kenji Jinno, Arsenic in shallow aquifer in the eastern region of Bangladesh: Insights from principal component analysis of groundwater compositions, Environmental Monitoring and Assessment, DOI:10.1007/s10661-009-0760-9,Vol.152,No.1, 2009.03.
17. IMPLEMENTATION OF STATISTICAL APPROACH FOR EVALUATION OF ARSENIC RELEASE MECHANISM IN GROUNDWATER OF BANGLADESH.
18. THE ANALYSIS FOR THE QUESTIONNAIRE SURVEY ON WATER OF FUKUOKA CITY CITIZENS BY SELF ORGANIZING MAP.
19. E. D.P. Perera, K. Jinno, A. Tsutsumi, Y. Hiroshiro, Numerical study of salinity variation in a coastal aquifer
A case study of the Motooka region in western Japan, Stochastic Environmental Research and Risk Assessment, 10.1007/s00477-008-0279-6, 23, 7, 957-965, 2009.01, 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..
20. M. A. Halim, R. K. Majumder, S. A. Nessa, K. Oda, Y. Hiroshiro, B.B. Saha, S. M. Hassain, Sk. A. Latif, M. A. Islam, Kenji Jinno, Hydrogeochemistry and Arsenic Contamination of Groundwater in the Ganges Delta Plain, Bangladesh, Journal of Hazardous Materials, ELSEVIER, DOI:101016/j_jhazmat.2008.09.046, 2008.10.
21. Abdur Razzak, Kenji Jinno, Yoshinari Hiroshiro, Md. Abdul Halim, Keita Oda, Mathematical modeling of biologically mediated redox processes of iron and arsenic release in groundwater, Environmental Geology, DOI 10.1007/s00254-008-1517-4, Springer-Verlag, 2008.08.
22. E. D. P. Perera, K. Jinno, A. Tsutsumi & Y. Hiroshiro, Numerical study of salinity variation in a coastal aquifer: a case study of the Motooka region in western Japan, Stoch. Environ. Res. Risk Assess, Springer- Verlag, DOI 10.1007/s00477-008-0279-6, 2008.08.
23. Md. Abdul Halim, Kenji Jinno, Abdur Razzak, Keita Oda, Yoshinari Hiroshiro, EXPERIMENTAL AND BIOGEOCHEMICAL MODELING STUDIES ON ARSENIC RELEASE IN SOIL UNDER ANAEROBIC CONDITION, The International Journal of Soil, Sediment and Water, Vol.1, No.2, ISSN:1940-3259, 2008.07.
24. M. A. Halim, R. K. Majumder, S. A. Nessa, K. Oda, Y. Hiroshiro, B.B. Saha, S. M. Hassain, Sk. A. Latif, M. A. Islam, Kenji Jinno, Groundwater contamination with arsenic in Sherajdikhan, Bangladesh: geochemical and hydrological implications, Environmental Geology, DOI 10.1007/s00254-008-1493-8, Springer-Verlag, 2008.07.
25. Kenji JINNO, Tosao HOSOKAWA, Yoshinari HIROSHIRO, Jun YASUMOTO, Geochemical Processes and their Modeling at the Fresh and Salt Water Mixing Zone, IAHS, IAHS Publ. No.312, 191-196, 2008.06.
26. Abdur RAZZAK, Kenji JINNO, Yoshinari HIROSHIRO, Md. Abdul HALIM and Keita ODA, Transport Model for Sequential Release of Mn, Fe and As under Anaerobic Soil Water Environment, MEMOIRS OF THE FACULTY OF ENGINEERING KYUSHU UNIVERSITY, Vol.68, No.1, pp.43-59, 2008.03.
27. Chemical interaction between arsenic and iron with changing redox condition.
28. REDOX PROCESSES BY ROCK-WATER INTERACTION IN SUBSURFACE ENVIRONMENT.
29. Edangodagee D. P. Perera, K. Jinno, A. Tsutsumi, Y. Hiroshiro, Simulation of Saltwater Intrusion caused Electric Conductivity Fluctuations due to Groundwater Pumping in a Coastal Aquifer, International Congress on Modelling and Simulation, CD-ROM,1582-1588, 2007.12.
30. Kenji JINNO, Tosao HOSOKAWA, Yoshinari HIROSHIRO, Jun YASUMOTO, Geochemical Processes and their Modeling at the Fresh and Salt Water Mixing Zone, ModelCARE2007(IAHS), pp.350~355, 2007.09.
31. TRANSPORT MODEL ON BEHAVIOR OF IRON(II) AT SALINITY TRANSITION IN COASTAL AQUIFER.
32. Jun YASUMOTO, Mamoru KATSUKI, Hidetomo TAKAOKA, Yoshinari HIROSHIRO, Kenji JINNO, Nutrient Inputs through Submarine Groundwater Discharge to Ariake Bay, Kyushu Island, Japan, IAHS(International Association of Hydrological Sciences), No.312, 159-168, 2007.07.
33. Yoshinari Hiroshiro, Kenji Jinno, Atsushi Tsutsumi, Masataka Matsumoto, Ronny Berndtsson, Estimation of Residence Time and Catchment Area for Spring Water Using Radioactive Isotope and Groundwater Flow Model, MEMOIRS OF THE FACULTY OF ENGINEERING KYUSHU UNIVERSITY, Vol.67, No.1, pp.1-9, 2007.03.
34. Othoman Ahmad ALKAEED, Atsushi TSUTSUMI, Kenji JINNO, Yoshinari Hiroshiro, Estimation of Surface Runoff and Groundwater Infiltration Components By the Groundwater Recharge Model (Itoshima Area, Japan), MEMOIRS OF THE FACULTY OF ENGINEERING KYUSHU UNIVERSITY, Vol.67, No.1, pp.11-23, 2007.03.
35. Jun Yasumoto, Mamoru Katsuki, Hidetomo Takaoka, Yoshinari Hiroshiro, Kenji Jinno, Upscaling of groundwater flow and geochemical transport to the Ariake Bay, in Kyushu Island, Japan, Proceedings of international symposium on “International between seawater and groundwater in the coastal zone and their effect on the environmental nutrient load toward the sea”, pp.99-100, 2006.12.
36. Keigo Akagi, Tosao Hosokawa, Yoshinari Hiroshiro and Kenji Jinno, Modeling of Physical and Geochemical Behaviors of Saltwater in a Coastal Aquifer, Advances in Geosciences, Vol.4, p.251-260, 2006.06.
37. Yoshinari Hiroshiro, Kenji Jinno, Ronny Berndtsson, Hydrogeochemical properties of a salinity-affected coastal aquifer in western Japan, HYDROLOGICAL PROCESSES, Vol.20, 1425-1435, 2006.04.
38. Yoshinari Hiroshiro, Kenji Jinno, Ronny Berndtsson, Hydrogeochemical properties of a salinity-affected coastal aquifer in western Japan, Hydrological Processes, 10.1002/hyp.6099, 20, 6, 1425-1435, 2006.04, 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..
39. Kazuro Momii, Yoshinari Hiroshiro, Kenji Jinno, Ronny Berndtsson, Reactive solute transport with a variable selectivity coefficient in an undisturbed soil column, Soil Science Society of America Journal, 10.2136/sssaj1997.03615995006100060001x, 61, 6, 1539-1546, 1997.01, 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..
Presentations
1. 広城 吉成, 小西 啓介, 寺嶋 健人, 堤 敦, Quantitative Analysis of Nutrient Inflow from River and Groundwater to Imazu Bay in Fukuoka, Japan, ICEWRM 2016:18th International Conference on Environment and Water Resource Management, 2016.05, 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.
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