2001 Fiscal Year Final Research Report Summary
On-the Study of Long-term Change of Hydrological data in the world rivers and the Assessment of the Stability of Water Resources
| Project/Area Number |
12650517
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
水工水理学
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| Research Institution | Kagawa University |
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Principal Investigator |
YOSHINO Fumio KAGAWA UNIV., FACULTY OF ENG., PROFESSOR, 工学部, 教授 (50311824)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Annual runoff / Lone-term variation / Sahel region / World rivers / Annual rainfall |
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| Research Abstract |
The global warming affects global hydrologic circulation. The effects on annual runoff may be reflected on the variation of long-term annual runoff series. I have analyzed the long-term annual runoff series in the 161 observation stations from 108 rivers in the world and assessed the stability of water resources in the world rivers. The next results were obtained.
1. Annual runoff at the rivers in Sahel region show the reducing tendency from 1960's but annual runoff at several rivers in North America and West Europe show weak increasing tendency in 1970's and 1980's.
2. The coefficient of variation of annual runoff during 1961-1990 become larger than that during 1931-1960 in several arid and semi-arid regions in the world.
3. The feature of hydrologic time series is appropriately assessed by the storage analysis for monthly runoff series.
Then, I studied more precisely the long-term variation of annual runoff in the Niger, the Senegal and the Chari river in Sahel region, with using annual rainfall data at 140 stations in 10 countries in this region. From this analysis, next results were obtained.
4. The reduction of runoff in these rivers in mainly based on the reduction of annual rainfall but not the human effects on the water resources.
5. The lowest annual rainfall in the Sahel countries was observed in the 1980's in almost all stations. However, the reduction ceased in 1990's and the decadal mean annual rainfall in 1990's increased compared with it in 1980's.
6. Long-term annual runoff in the Niger and the Senegal rivers show the weak periodical variation of about 30 years. It will be anticipated that if based on this weak semi-periodical nature of annual runoff, annual runoff of these rivers may decrease in the end of 2000's to 2010's.
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Research Products
(7 results)
