大沙河流域降水变化与输沙关系的研究

Variation of Rainfall in Dasha River Watershed and Its Connection to Sediment Transport

对皖西南大沙河流域1954～1999年的降水记录和该流域1970年以来的逐月径流和输沙量资料分别进行了趋势分析和关联分析,发现46年来,地处皖西南大别山区的大沙河流域降水的季节和年际变化异常显著,且降水有下降趋势,流域春季、夏季和全年的降水变化率分别为-7.4mm/10a,-13.06mm/10a和-4.6mm/10a。通过对同期降雨、径流和输沙量各因子相互间的灰色关联分析发现大沙河流域输沙量与日雨量大于100mm和50～100mm的暴雨次数关联最密切,其关联系数分别达到0.98和0.90,说明皖西南大别山地区降雨强度特别是大于100mm的特大暴雨和50～100mm的暴雨对地表侵蚀最为严重,是造成本地区水土流失的主要因素;此外,人类活动特别是人口和耕地面积的增加也是导致本地区水土流失的重要原因。

Based on the observational records covering the period from 1954 to 1999,the characteristics of precipitation changing in dasha river watershed and its connection to sediment yield were studied using tendency analysis and correlation analysis .Results showed that the rainfall in this watershed had a down tendency in spring at a rate of -7.4 mm/10 a,summer and Annual precipitation at a rate of -13.06 mm/10 a and -4.6mm/10 a. The correlation analysis shows that the amount of sediment transport has a very close relation with rainstorm of 100 mm and 50~100 mm of daily rainfall.