坪上水库径流还现计算分析

拟建的坪上水库位于滹沱河干流上,水库1956-2001年年平均还原径流为7.23亿m3,经分析,还原径流成果基本合理,但还原径流系列一致性不好,主要原因是由于人类活动的影响,使流域的产汇流机制和渗漏机制发生了改变,从工程建设依据要求出发,提出了径流还现修正的必要性。还现修正,即把早期下垫面状况下产生的径流量修正为现状条件下的径流量。修正的原理和方法即在径流还原计算的基础上,点绘水文站流域平均雨量与还原径流深相关图,分别通过前、后期点群中心绘制其降水-径流深相关线,两线之间横坐标距离即为由于受人类活动影响使年径流深减小的幅度。还现修正后水库的天然径流量为6.33亿m3,流域前、后期降水-径流深关系曲线基本趋于一致,反映了近期流域的实际状况,为工程规模和效益的确定提供合理科学的依据。

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 .