东江上游河流水沙分析

Runoff and sediment characteristics in the upper East River

分析了东江上游地区河流水沙特性,并阐述了水库的修建和运用对该地区水沙输移的影响。东江上游地区是整个流域泥沙的重要来源区,该地区地表径流主要来自于降水,河流泥沙也主要来自于降水和径流所造成的土壤侵蚀。从长系列看,东江上游地区径流量虽然在不同时期波动较大,但相对稳定,而河流输沙量呈下降趋势。东江上游来水来沙主要集中在每年的汛期,其汛期来水来沙量分别占全年的70%和88%。枫树坝水库和枕头寨水库建成运用,减小了径流量的季节差异,降低了河流流量脉动特性。同时其河流输沙率在枫树坝水库和枕头寨水库建成以及枕头寨水库调整后分别下降了30%和50%。近年来,东江下游进行的大规模无序采沙,其采砂量已经远大于上游来沙量。在东江流域进行水沙管理时,不仅要采取措施遏制这种无序采沙行动,同时也要进一步研究流域水沙输移问题,以达到维持整个河流系统的水沙平衡。

The paper analyzes the runoff and sediment characteristics of the upper East River, as well as expounds the impacts of reservoirs on the runoff and sediment transportation. The upper East River is the main sedimentproducing area in the East River Basin. Surface runoff over the upper East River comes from precipitation, and sediment is mainly from soil erosion. In general annual runoff at Longchuan hydrological station keeps stable through years, while sediment load tends to decrease. There are about 70% of annual runoff and 88% of sediment load during the flood season. The Fengshuba Reservoir and the Zhentouzhai Reservoir have reduced seasonal differences of runoff and the flow fluctuations at the Longchuan hydrological station. Compared with the natural scenario, reservoirs have reduced the sediment transport rates. As a result, the amount of sediment transported to the downstream channel decreases. From 1980s, extensive sediment evacuating has occurred in the basin, especially in the lower reach, and the evacuted sediment load has exceeded sediment from the upstream area which exacerbate the imbalance of sediment over the basin. Therefore for the water and sediment management in the East River Basin, it is very urgent to restrain disorderly sediment mining and take neccessary measures to maintain the water and sediment balance over the basin.