长江河口南港采砂对河床稳定性的影响

The Effect of Sand Digging to Bedfrom Stability of the Nangang Channel in the Changjiang River Mouth

利用多波束测深及数字高程模型技术发现：南港主槽有若干长50-100m,深3-5m的采砂坑;瑞丰沙体南侧存在高0.5-1.2m,长约1800m的两级陡坎,陡坎下有长1850m、宽400m、体积124.5万立方米的滑坡体。近8年来,瑞丰沙冲刷减少3724万立方米。采砂坑、陡坎与滑坡体形成的主要受采砂及其引起的瑞丰沙顶部水沙通量调整控制,采砂引起瑞丰沙顶部过水断面增加8240m^2,涨潮从南小泓分流0.96亿立方米,落潮从南港主槽分流1.43亿立方米。

According to the bed-form data measured by multi-beam echo-sounding system（MBES） and digital elevation model（DEM）,this parer is to examine the impacts of pumping-sand on the river bed-form evolution of the Nangang Channel in the Changjiang River mouth.The results is that there were 5 huge sandpits with 50-100m long and 3-5m depth,2 ranges steep ridge with 1800m long and 0.5-1.2m high and 1 huge landslide with 1850m long and 400m wide in Ruifeng shoal edge nearly sandpits in the Nangang Channel,and the volume of landslide reached 1.245×10^6m^3.Furthermore,our data have further demonstrated such bed-from evolutions mainly resulted from human pumping-sand.Reifeng shoal were obviously eroded and the volume decreased 3.724×10^7m^3 recently 8years.It decreased 8240m^2 of longitudinal profile area of the middle Ruifeng shoal,and that resulted in water discharge increasing separately 0.966×10^8m^3 in flood tide and 1.43×10^8m^3 in ebb tide.