1950年以来鄱阳湖流域水沙变化规律及影响因素分析

运用Mann-Kendall趋势检验法和回归分析等方法,对鄱阳湖流域赣江外洲站、抚河李家渡站、信江梅港站、饶河虎山站和修水万家埠站1950~2012年径流量和1956~2012年输沙量的变化进行了系统分析,并探讨了水沙变化的原因。研究结果表明:(1)鄱阳湖流域五大河流水沙的趋势变化特征相异,除李家渡站径流无明显趋势变化外,其余各站均呈不显著的增加趋势(未超过α=0.05显著性检验临界值);外洲站、梅港站和李家渡站输沙量呈减少的趋势变化,且1985年以后呈显著的减少趋势,而虎山站和万家埠站输沙量在1965~1999年呈不显著的增加趋势,1999年以后才开始减少;(2)入湖总水量呈不显著的增加趋势,发生突变的年份为1992年;入湖总沙量呈显著的减少趋势,发生突变的年份为1996年,入湖总沙量突变滞后于入湖总水量;(3)流域径流量变化主要受降雨量的影响,而输沙量变化主要受水土保持和水库建设等人类活动的影响,且水库拦沙是鄱阳湖流域输沙量减少的主要原因。

SPATIAL AND TEMPORAL CHANGES OF RUNOFF AND SEDIMENT LOADS IN THE POYANG LAKE BASIN SINCE 1950 AND THEIR INFLUENCE FACTORS

The Poyang Lake is the largest freshwater lake in China, and also one of the globally important ecological area delimited by World-Wide Fund for Nature. It plays an important function on the flood regulation and the conservation of biological diversity in the Yangtze River Basin. However, due to influences of climate change and human interferences, increased frequency of lower water levels in the dry season, decreased lake area, frequent drought-flood abrupt alternation and the destruction of the ecological system in the Poyang Lake Basin have emerged, and caused extensive attentions of the whole society. Hence, By using Mann-Kendall trend test and regression method, changes of annual runoff from 1950 to 2012 and annual sediment loads from 1956 to 2012 at five hydrological gauging stations (Waizhou, Lijiadu, Meigang, Hushan and Wanjiabu) in the five tributaries (Ganjiang River, Fuhe River, Xinjiang River, Raohe River and Xiushui River) of the Poyang Lake Basin were analyzed, and the causes underlying runoff and sediment changes were discussed. The results showed that (1) characteristics of the changes in runoff and sediment loads were different among the five tributaries of the Poyang Lake Basin. No significant trend of annual runoff was found at the Lijiadu station, while the other gauging stations showed an increasing trend. The sediment loads showed a decreasing trend at the Waizhou station in the Ganjiang River, the Meigang station in the Xinjiang River, and the Lijiadu station in the Fuhe River (the decreasing trend at the Waizhou station and the Meigang station are significant at > 95% confidence level after the year 1985), but increasing trend at the Hushan station in the Raohe River and the Wanjiabu station in the Xiushui River during the period of 1965-1999, and then began to decrease. (2) Total runoff into the Poyang Lake showed no significant increasing trend, and its abrupt alteration year is 1992. Total sediment transportation into the lake showed a significant decreasing trend, and its abrupt alteration year is 1996. (3) The annual runoff changes were mainly affected by precipitation, the annual sediment loads changes were mainly affected by water and soil conservation and the water reservoir construction. Sediment capture by water reservoir was found to be the major cause underlying the decrease of sediment loads in the Poyang Lake Basin. These results are of great significance for better understanding on the spatial and temporal changes of runoff and sediment loads in the Poyang Lake Basin and influences of climate change and human interferences on the hydrological processes.