气候变化和人类活动对鄱阳湖流域入湖输沙量影响的定量估算

采用HydroTrend水文模型,以鄱阳湖流域的赣江、抚河、信江、饶河和修水为研究对象,基于1956-2010年鄱阳湖流域气候数据、水沙数据及其他相关资料,分别模拟了5个子流域的入湖水沙通量变化。在此基础上,探讨了气候变化、植被覆盖变化和水库修建活动对输沙量变化的影响,并定量估算了上述因子对流域输沙量变化的贡献。结果表明：① 1956-2010年,气候、植被和水库三种因子影响下的流域年均输沙量分别为15.5 Mt、20.8 Mt、8.5 Mt,而三种因子共同影响下的流域年均输沙量达到12.6 Mt。② 1956-2010年,植被覆盖变化使流域年均输沙量增加4.2 Mt,而水库拦截造成流域年均输沙量减少8.2 Mt,两者分别占实际年均输沙量的32.4%和63.2%。③ 1956-1989年,植被覆盖变化导致的输沙增加量和水库修建拦截导致的输沙减少量均为5.1 Mt/a,两者对流域输沙量贡献持平;1990-2010年,水土流失加重导致的输沙增加量和水库拦截导致的输沙减少量分别为2.7 Mt/a和13.3 Mt/a,水库对入湖输沙量的影响效应是植被覆盖变化的5倍左右。

The quantitative estimation of sediment load changes entering Poyang Lake Basin induced by climate change and anthropogenic impacts

The numerical model HydroTrend is applied to simulate the variations of water discharge and sediment fluxes into Poyang Lake during 1956- 2010 from the five tributaries of Poyang Lake Basin, namely Gan, Fu, Xin, Rao and Xiu rivers. Furthermore, the influences of climate change, vegetation cover variation and reservoirs construction on the sediment load are analyzed, and the contribution of the above three factors to the sediment load entering the Poyang Lake is quantitatively evaluated. The results show that, during the period of 1956-2010, the average annual sediment discharge into Poyang Lake under the influence of climate, vegetation cover and reservoir construction reached 15.5 Mt, 20.8 Mt, 8.5 Mt, respectively; whereas, the sediment load entering the Poyang Lake under the combined-influence of the above three factors is 12.6 Mt a^-1. In addition, during the same period, the sediment load delivered to the Poyang Lake increased by 4.2 Mt a^-1 due to water and soil erosion, and decreased by 8.2 Mt a^-1 attributed to reservoir interception, which accounted for 32.4% and 63.2% of the observed sediment load discharged into the Poyang Lake, respectively. From 1956 to 1989, the increased sediment load caused by water and soil erosion and the decreased sediment load induced by dam emplacement, in terms of both quantity of 5.1 Mt a^-1, is equivalent; However, during 1990-2010, the sediment load resulting from water and soil loss decreased to 2.7 Mt a^-1, and that intercepted by reservoirs increased to 13.3 Mt a^-1, suggesting that the effect of reservoirs construction on the changes of sediment load entering the Poyang Lake is 5 times of that of water and soil erosion.