黄河尾闾沙洲及河口形态对水沙变化的响应

Responses of the processes in the Yellow River lowermost channel sandbars and estuary to the variation of water and sediment

基于多源高分辨率卫星数据和实测地形资料对黄河尾闾河道沙洲、河口沙嘴及滨海区对水沙变化的响应过程进行多尺度分析。结果表明:2013-2015年,黄河水沙逐年减少,河口沙嘴横向淤长,拦门沙形态由长条形逐渐转为类似圆形;2016-2017年,水沙锐减,调水调沙中断,河口沙嘴及滨海区遭受冲刷;2018-2020年重启调水调沙工程,黄河水沙陡增,河口沙嘴沿出汊口方向大面积堆积造陆,拦门沙形态由类似圆形快速转变为马鞍形,面积增加5.96 km^(2)。滨海区淤积广泛,尤其是在北汊口附近。年内尺度上,2017年低流量时河道两侧分布大量沙洲,尤其是在弯曲河段,并持续向河中心发育。2018年汛期的调水调沙工程重塑了沙洲的空间分布格局,使其减少60%,而且还推进了沙嘴短时间内迅速向海淤进。

Based on the satellite data and topographical data,the morphological processes of the riverine sandbars of the Yellow River lowermost,estuarine sandspit and submerged delta were analyzed at multiple spatiotemporal scales.Results show that during 2013-2015,the water discharge and sediment load of the Yellow River decreased,which leaded to the sandspit developing horizontally,and the shape of estuarine sandbar gradually changed from the strip to the quasi-circular.During 2016-2017,runoff and sediment of the Yellow River decreased sharply and Water-Sediment Regulation Scheme(WSRS)was interrupted,which caused scour of estuarine sandbar and coastal area.The river runoff and sediment increased sharply and WSRS was restarted after 2018,resulting in large areas of land generated in the sandspit along the two branch mouths.The area of estuarine sandbar was increased by 5.96 km^(2)and its shape quickly changed from the quasi-circular to the saddle.The WSRS during the flood season in 2018 reshaped the spatial distribution pattern of riverine sandbars,reducing it by 60%.Moreover,WSRS also prompted the estuarine sandspits to advance toward the sea at high speed.