森林植被改善对鄱阳湖流域径流和输沙过程的影响

以河流基流为切入点,研究流域植被调节径流、水土保持等微观作用影响大中型河流湖泊径流过程和水沙过程宏观效应的机理。鄱阳湖流域60年来天然降水没有发生趋势性变化。流域森林覆盖率由34.73%上升到63.00%,植被质量改善,赣江等入湖河流基流增加83 m~3/s,河流输沙量减少。2000年以后和2000年以前相比较,枯水期降水径流系数增大,年流量过程平坦化,一定程度上减小洪灾风险,有利于水资源利用和生态环境保护。2001年以后进入鄱阳湖泥沙平均每年减少1 007×10~4t;出湖泥沙增加314×10~4t。因此,鄱阳湖入江水道由淤积转变为冲刷,但出湖流量过程没有趋势性变化。

Effect from forest vegetation improvement on runoff and sediment transport processes within Poyang Lake Watershed

Starting from river base flow，the mechanisms of themicroscopic effects from the runoff regulated by vegetation，water and soil conservation，etc. on the macroscopic effects from the runoff process and the water and sediment process of large medium sized rivers and lakes within a watershed are studied herein. In the past 60 years，no any trend changes of natural precipitation are there in Poyang Lake Watershed. The forest coverage increases from 34.73% to 63% with the enhancement of the quality，while the base flows from Ganjiang River，etc. into the lake are increased by 83 m3/s with the decrease of the river sediment load. The precipitation runoff coefficient is increase after 2000，if compared with that before 2000，and then the annual flow hydrograph is flatted and reduces the flood risk to a certain extent，thus is favorable for the utilization of water resources and the eco environment protection. After 2001，the inflow sediment into Poyang Lake is averagely reduced by 1 007×104t every year，while the outflow sediment is increased by 314×104t. Therefore，the water channels from Poyang Lake to the river are converted from sedimentation to erosion，but there is no trend change of the hydrograph of the outflow from the lake.