Calculation Analyse of Current Runoff in Pingshang Reservoir

The proposed Pingshang Reservoir will be located on the trunk stream of Hutuo River and the annual average natural runoff from 1956 to 2001 is 0.723 billion m~3.After analyzing, the outcome of natural runoff is essentially reasonable, but the consistency of natural runoff series are not very well. The main reason is the influence of human activities changing the mechanism of accordant junction and seepage. So according to the project construction requirements, the article puts forward the necessity of modifying runoff which is a method of modifying the early runoff of ground surface conditions to be current runoff. The modifying principles and methods are described as follows, i.e. on the basis of natural runoff calculation, the relationship chart of average rainfall of hydrology station drainage area and natural runoff depth has been plotted and the relationship of rainfall and runoff depth curve also has been plotted by early and latter centre of group of spots, then the distance between the X-coordinate is the reduced depth of annual runoff depth due to the influence of human activities. The modified natural runoff is 0.633 billion m~3 and the relationship curve of early and later rainfall and runoff depth is basically consistency , reflects the actual recent situation of drainage area and will provide reasonable and scientific base for determining project scale and profit .