宁夏清水河流域水库拦沙量分析

为了解宁夏清水河流域水库的拦沙作用,研究根据泥沙淤积总量来计算逐年拦沙量的方法。根据实测资料统计分析了清水河流域水库的基本情况,估算了水库的总拦沙量,并引入水库控制面积、土壤侵蚀强度、拦沙率3个因素建立了水库逐年拦沙量的分配计算模型。结果表明,至2012年,清水河流域共有具拦沙功能的水库100座,控制面积9 184.70 km~2,总库容12.23亿m~3,可淤积库容6.86亿m~3,拦沙总量5.71亿m~3,为同期泉眼山输沙量的78.25%。对模型计算结果的验证表明,在当水库数量比较多、分布比较均匀的条件下模型计算结果精度较好。根据计算结果,1979年以前时段水库拦沙量比较大,1980年以后由于水库建设速度减慢,水库的拦沙能力逐渐变小。自1960年以后水库的剩余可淤积库容一直处于下降的状态,2000年以后水库的淤积比处于83.00%左右,水库的拦沙能力已经十分有限。

Analysis of Sediment-Retaining Amount by Reservoirs in Qingshuihe Watershed of Ningxia

The reservoirs of Qingshuihe basin in Ningxia have important role on sediment-retaining effect, which is also an important factor to be considered in the revert calculation of sediment yield. However, how to calculate the annual sediment-retaining amount based on the total amount of sedimentation has ever been rarely reported. Based on the measured data, the basic situation was analyzed and the total sediment-retaining volume of the Qingshui River Basin reservoirs was estimated in this paper. Three factors of control area, average erosion intensity and sediment-retaining rate were introduced to establish the calculation formula for the annual sediment retention by reservoirs. Analysis based on statistics showed that there were 100 reservoirs in the Qingshuihe basin, the total capacity was 12.23×10⁸ m³, the controlled drainage area was 9 184.70 km², the total storage capacity was 1.235 billion m³, the sediment-retaining capacity was 686 million m³, and the sediment-retaining volume was 571 million m³, which accounted for 78.25% of sediment transported at Quanyanshan Hydrological Station in 1957 to 2012. The verification of the calculation results showed that the model had good calculation accuracy when the number of reservoirs was large and the distribution was relatively uniform. According to the calculation results, the sediment retaining volume of the reservoir was relatively large before 1979. Since 1960, the remaining sediment-retaining capacity of the reservoir declined. After 2000, the sediment-retaining ratio of the reservoirs remained about 83.00%, it showed that the reservoirs showed a limited capacity in the sediment-retaining.