珠江口黄茅海拦门沙演变及成因分析

The analysis of the evolution of a sand bar and its formation in the Huangmao Bay of the Zhujiang Estuary

采用1977,1994,2003,2010年4个年份的地形图,建立了DEM模型,结合二维水动力模型对近30多年来黄茅海拦门沙演变的特征及成因进行了分析。研究表明近30多年来黄茅海拦门沙平面上向海推移,范围缩小,在内坡和拦门沙顶冲刷,在外坡淤积;拦门沙的基本成因是其位于上溯流与下泄流控制区域之间的过渡带,该过渡带为明显的动力较弱的区域,泥沙较易在此处沉积;黄茅海大面积的围垦导致纳潮量减少、潮汐动力减弱、径流作用相对增强,使下泄流控制区扩大、上溯流控制区减小、过渡区下移,这是拦门沙冲刷外移和缩小的主要原因。上游来沙量减少加剧了拦门沙冲刷外移和缩小。

The DEM model is established using the bathymetric maps of years of 1977,1994,2003 and 2010,and combined with the 2D model,the evolution of a sand bar in the Huangmao Bay and its formation are studiod in recent 30 a.show that the sandtbar moves to the sea and becemes smaller,its inner slope and top are scoured and outer slope is silted.The formation of the sand bar is mainly located in the weak dynamic zone of the transitional zone between flood flow dominant and ebb flow dominant zones.The decrease of the tidal volume,the weakening of the tidal dynamics and the relative strengthening of the runoff caused by large reclamation,which result in that the ebb flow controlled zone is enlarged,the flood flow controlled zone reduces and the transitional zone moves down,are the main reasons of the sand bar evolution.The reduction of sediment transported by the runoff also contributes to the sand bar evolution.