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| Temporal variations and trend analysis of runoff in Qingjianhe River in Yellow River midstream area in the past 50 years |
| Wang Jiping1, Zhao Mei2, Cheng Fu3, Jiang Lei4, Wang Ran5 |
| 1.Research Institute of Forest Ecology, Environment and Protection,the Chinese Academy of Forestry, 100091, Beijing; 2.Bureau of Hydrology and Water Resources of the Middle Yellow River, Yellow River Water Conservancy Committee, 030600, Jinzhong, Shanxi; 3.Beijing Watersoil Conservation and Ecoengineering Consultation Co., Ltd, 100055, Beijing; 4.College of Forestry, Beijing Forestry University, 100083, Beijing; 5.National Satellite Ocean Application Service, 100081, Beijing: China |
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Abstract Based on the data set of runoff of the Yanchuan Hydrological Station, Qingjianhe River, in the past 50 years, annual unevenly distribution coefficient of runoff, complete accommodation coefficient, concentrative degree (concentrative period), variation coefficient and runoff extremum ratio of the station were calculated and analyzed, which indicated the annual and interannual variations of runoff. The longterm variation tendency of the runoff in the Qingjianhe River Basin was verified by the tendency analysis method. The results demonstrate that the annual analytic curve of annual distribution of runoff in Qingjianhe River Basin occurred unimodal curve, and the runoff mainly distributed during July to September, which accounted for 58% of average annual flow. Since 1990s, the annual unevenly distribution and concentrative degree had a gradual decrease. The interannual runoff in different periods varied so greatly to reach the peak of past 50 years after 2000. The annual runoff in this basin presented a significant downtrend, which was supported by the facts that 1980s was the remarkable turning point of the runoff from high to low water level period, and after 2000 runoff turned into the lowwater period and reached the lowest level in the past 50 years. The evolution of runoff in Qingjianhe River Basin shows the clear nonuniformity, periodicity and tendency, which is related with the rainfall and characteristic variation of underlying surface caused by restoring vegetation.
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Received: 22 April 2011
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