近40年赣江年径流泥沙变化及影响因素分析

为了掌握鄱阳湖水系第一大河——赣江长时间序列的径流泥沙演变规律,运用Mann-Kendall秩次相关趋势分析法和均值差异T检验法对1970-2009年赣江年径流量和年输沙量进行分析。结果表明:近40年来赣江年径流量没有发生明显变化,而年输沙量呈显著下降趋势;年输沙量分别在1984,1992年发生了突变,1970-1983年、1984-1991年和1992-2009年这3个阶段的年均输沙量分别为2 281.27×107,803.75×107,462.72×107 kg,相应变点的跃度依次为1 477.52×107,341.03×107 kg,这与利用径流—泥沙双累积曲线法得到的年输沙量阶段性分析结果一致。在1970-2009年赣江年降水量无明显变化的情况下,其年输沙量显著减少主要系人为作用,主要是水土保持综合治理和水利工程拦沙导致赣江入鄱阳湖泥沙量每年减少约40.53×107 kg。

Analysis on Evolution Characteristics and Impacting Factors of Annual Runoff and Sediment in the Ganjiang River During 1970-2009

In order to find out the evolution characteristics and its impacting factors of annual runoff and sediment in the Ganjiang river during 1970-2009,Mann-Kendall method and average difference T method were used in this paper.The results show that the amount of annual runoff in recent 40 years has no evident varieties and the annual sediment transportation has appeared obvious descendent trend.Moreover,with the application of sudden change point searching technology,the paper comes to a conclusion that the annual sediment transportation change duration of the Ganjiang river may be divided into three periods,1970-1983,1984-1991 and 1992-2009.The average annual sediment transportation of the above three periods is 2 281.27×107,803.75×107,462.72×107 kg,respectively.The leap-degree of every stage sediment transportation is 1 477.52×107 kg and 341.03×107 kg.The result is consistent with the data obtained by the double accumulation curve method.In order to find out the impacting forces of the annual runoff and sediment transportation changes,the relationships between precipitation,runoff and sediment transportation variation were analyzed.It is quite clear that human activities were the main reason causing the sediment transportation descent for nearly 40 years.Thus,the sediment from the Ganjiang river to the Poyang lake decreased by 40.53×107 kg every year accordingly.This study is not only helpful for ecological construction of soil and water conservation,but also helpful for rational development of water resources.