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| Analysis on historical evolution and driving force of rainfall and runoff of Harbin Station in Songhua River |
| Song Xiaoyan1,Mu XingMin1,2,Gao Peng1,2,Wang Fei1,2,Wang Shuangyin2 |
1.Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources;2.Institute of Soil and Water
Conservation,Northwest A & F University: 712100 ,Yangling,Shaanxi,China |
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Abstract As rainfall and runoff are important natural forces to cause soil erosion,studying characteristics of runoff and its affecting factors has significance to understand the laws of soil erosion.Long sequence data of 1909—2005(lack 1943—1952) of the rainfall and runoff and the methods of runs theory,Mann-Kendall and double mass curve were used,and annual variability of the average rainfall and runoff depth of Harbin Station on the Songhua River were analyzed.The results show that: Over the past 87 years,average rainfall is 501.7 mm, and average runoff depth is 106.3 mm.In Harbin Station,positive run-length of average rainfall and runoff depth are 1.7 years and 2.1 years respectively,which are less than their negative run-length 2.0 years and 2.7 years respectively.So rainfall and runoff are even more likely to appear dry years.Although there are no obvious trends in the average rainfall and runoff depth,there are significant stage characters.Both rainfall and runoff depth may be divided into three wet stages,one flat stage and three dry stages.Due to human activities,the rainfall-runoff sequence may be divided into 1909—1915,1916—1927,1928—1978 and 1979—2005 four phases.
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Received: 15 August 2009
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