1991 Fiscal Year Final Research Report Summary
Study on the Recharge Mechanism and Development of Groundwater in the Inland area of Tanzania
| Project/Area Number |
01041013
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Field Research |
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| Research Institution | Chiba University |
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Principal Investigator |
SHINDO Shizuo Faculty of Sciences, Chiba University, 理学部, 教授 (70058014)
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| Co-Investigator(Kenkyū-buntansha) |
KONGOLA L. R. E Ministry of Water, Tanzania, 地下水局, 研究官
KONDO Akihiko Faculty of Science, Tokyo Metropolitan University, 理学部, 助手 (30201495)
SATO Yoshinori faculty of Education, Joetsu University of Education, 学校教育部, 助教授 (40143185)
SAKURA Yasuo faculty of Sciences, Chiba University, 理学部, 助教授 (70153947)
MATSUMOTO Eiji Institute of Geoscience, University of Tsukuba, 地球科学系, 助教授 (10015571)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Tanzania / groundwater recharge / stable isotope / radio isotope / semi-arid area / infiltration capacity / groundwater management / 安定同位体 |
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| Research Abstract |
In the Makutapora Basin in central Tanzania, mean annual rainfall is about 600 mm while potential evaporation is 2470 mm. Thus groundwater recharge is highly dependent on the amount and pattern of rainfall. To understand the mechanism of groundwater recharge in the basin and surrounding area, a small watershed was selected and intensive hydrological observations were carried out. The relationship between actual evaporation and soil water content was derived from weighing lysimeter and the runoff ratio of representative sites were calculated from the measurement of infiltration capacity. Those results are combined to simulate water balance in the unsaturated zone and recharge is calculated to be 15 % of rainfall.
Groundwater in the Makutapora Basin is divided into shallow groundwater and deep confined groundwater. The latter is then classified into type-1 and type-2 according to chloride ion concentration. The residence time of deep confined groundwater is generally more than 25 years, probably a few tens years, whereas the residence time of shallow groundwater is shorter than 20 years. P_<CO2>, tritium concentration and stable isotope composition also show that type-1 is the component from Chenene Hill area and type-2 is the component from the upper plane near the basin floor.
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