降雨因素对大清河流域洪水径流变化影响分析

选择大清河流域的两个子流域，对其洪峰和洪量的变化趋势进行了分析，统计了1956~1980年和1980~2002年两个时段一定频率洪水发生的次数，发现两个子流域洪水次数和量级呈减小的趋势。并分析了降雨因素对洪水变化趋势的影响，结果表明，次降雨量和降雨强度均有减少趋势，一定频率降雨发生的次数在1981~2002年比1956~1980年有明显的减少，汛期降雨量和雨季平均日降雨量也呈减少趋势，以及暴雨空间分布发生了一定的变化，这些降雨因素对洪水次数和量级的减小具有一定的影响。

The Effects of Precipitation on Flood Variations in Daqinghe River Basin

The trends of flood peaks and volumes were analyzed in two sub-catchments of Daqinghe river basin. The number of occurrences of floods during 1956~1980 and 1981~2002 was calculated, and it was found that the number of occurrences, flood volumes and peaks decreased. So the influence of precipitation on floods was studied, and the results showed that the largest rainfall depth and intensity each year reduced, the number of occurrences for rainfall during 1981~2002 was less than that during 1956~1980, rainfall depth in flood season and the mean day-rainfall in rainny season also showed a trend of reduction, and the spatial distributions of rainstorms changed. All of these factors can result in the decrease of flood magnitude in Daqinghe river basin.