长江口河口河槽浅地层剖面探测研究

Detection and Research by Sub-bottom Profiler in Changjiang Estuary

于2010年枯季利用浅地层剖面仪等对长江口自江阴至北港、北槽和南槽口门段河槽浅部地层进行探测。探测结果显示：江阴至徐六泾段落潮流占绝对优势,床沙质以细砂为主,发育有波长约15~25m、波高约0.5~0.8m的沙波;自徐六泾至口门段河槽床面受势力相当的涨、落潮流影响,河槽床面仅偶尔发育有较小尺度的沙波,波长5.0~12m,波高0.2~0.5m,大部分为平床,但南北槽较南北港及南支河槽发育有更多沙波,本段浅部地层多发育有两到多层沙波分层,这主要受近年来流域来水来沙变化和河口大型工程影响导致的沙洲冲淤频繁堆积的影响。

Detection by sub-bottom profiler was made from Jiangyin to north channel,north passage and South Passage during the Changjiang estuary during the dry season of 2010.The results showed that majority of subaqueous dunes with a spacing of 15~25m and height of 0.5~0.8m on the riverbed with few stratification in the main channel from Jiangyin to Xuliujing where the ebb current was dominated.Less subaqueous dunes occurred with a spacing of 5.0~12m and height of 0.2~0.5m on the riverbed with some stratification of channels from Xuliujing to themouth area of north channel,north passage and south passage where flood and ebb current were alternating.Nevertheless,more subaqueous dunes were distributed in the North and South passage than those in north and south channel and south branch.There are two or more layers in the sub-bottom profiler in most areas,which is possibly responsible to complex scouring and silting in the riverbed,for the recent variation in dynamic environments and sediment source induced by large engineering projects located in the estuary and upstream catchment.