宁夏清水河流域淤地坝拦沙量分析

Analysis of sediment-retaining by check-dams in Qingshuihe river watershed of Ningxia

对淤地坝逐年拦沙量进行还原计算具有重要的理论及实际应用方面的意义。在对2012年清水河流域淤地坝拦沙量实测资料进行统计分析的基础上,引入坝控流域面积、平均侵蚀强度、拦沙率三个因素建立了淤地坝逐年拦沙量计算公式,计算了清水河流域1971-2012年间淤地坝的逐年拦沙量,并依据计算结果对淤地坝拦沙情况进行了初步分析。根据实测资料统计,至2012年清水河流域共有淤地坝302座,总拦沙量0.17亿m^3,淤积比为47.39%。计算结果表明,2000年以前淤地坝拦沙量在70万t以下,2000年以后多数年份拦沙量在100万t以上, 2010年以后淤地坝拦沙量占流域侵蚀产沙量的比例超过11%。本计算模型建立在大量淤地坝均匀分布在流域内及拦沙率呈指数型分布的前提条件下,在不同条件下的运用还需要对模型做进一步地改进。

It is great significance to calculate the annual sediment-retaining by the check-dams. Based on the measured data of sediment retained by the check-dams in 2012, three factors of control area, average erosion intensity and sediment-retaining rate were introduced to establish the calculation formula for the annual sediment-retaining by check-dams, and annual sediment-retaining volume in the check-dams in the Qingshuihe river basin from 1971 to 2012 was calculated. According to the calculation results, a preliminary analysis of the check-dams condition was carried out. According to the statistics of the measured data, there were 302 check-dams in the Qingshuihe river basin by 2012, total sediment-retaining was of 0.17 billion m^3, and sediment-retaining ratio was of 47.39%. The calculation results show that before 2000, the sediment-retaining by the check-dams was below 0.7×10^6t. After 2000, the sediment-retaining by the check-dams was more than 1.0×10^6t, and that accounted for more than 11% of the erosion and sediment production in the Qingshuihe river watershed. The model is based on the two conditions of large number of check-dams that are evenly distributed in the basin and the sediment-retaining ratio is exponentially distributed. If the model was used under different conditions, it should be further improved.