近60年来韩江入海泥沙通量变化及其对邻近海域的影响

Changes in Sediment Flux from Hanjiang River into the Sea and Its Influence on Adjacent Sea Areas over the Last 60 Years

为研究近60 a来韩江入海泥沙通量的变化及其环境效应,采用Mann-Kendall方法对潮安水文站1958—2019年入海径流量和泥沙通量进行检验,并分析影响入海泥沙通量变化的主要驱动因素,以及入海泥沙变化对邻近海域的影响。研究结果显示韩江流域入海径流量无显著变化,入海泥沙通量呈现显著的减少趋势,并在1998年开始显著减少,在2001年之后减少更为剧烈。韩江流域大型水电站(青溪、棉花滩水电站)是导致入海泥沙通量开始显著减少的主要影响因素。在入海泥沙自1990s末显著减少的背景下,韩江河口附近海域由1971—2010年的小幅淤积转变为2010—2016年的小幅冲刷。三角洲岸线由1830s—1964年的向海推进(2.40~5.38 m/a)转变为1980s以来的较为稳定。这些都表明韩江入海泥沙的显著减少已经对河口邻近的海域产生了明显的影响。

In order to study the changes in sediment flux from the Hanjiang River into the sea and its environmental effects over the last 60 years,this paper uses the Mann-Kendall method to test the runoff discharge and sediment flux measured by the Chao’an hydrological station from 1958 to 2019,analyzes the main driving factors affecting the changes of sediment flux,and investigates the impact of sediment flux changes on adjacent sea areas.The results show that there is no significant change in runoff discharge for the Hanjiang River.The sediment flux into the sea has significantly decreased since 1998,and it has dropped more sharply since 2001.The large hydropower stations(Qingxi and Mianhuatan hydropower stations) in the Hanjiang River Basin are the main factors that lead to the significant decrease in the sediment flux into the sea.Since the sediments into the sea decreases greatly at the end of the 1990 s,adjacent sea areas near the Hanjiang estuary have witnessed a transformation from slight sedimentation during 1971—2010 to slight erosion during 2010—2016 and a change of the delta shoreline from progradation(2.40~5.38 m/a) during 1830 s—1964 to relative stability in 1980 s.These findings indicate that the remarkable decrease in sediments from the Hanjiang River into the sea has greatly affected adjacent sea areas near the estuary.