长江马鞍山河段洲滩演变特征及影响因素分析

Evolution characteristics of sand bars and its determine factors in Ma’anshan reach of Yangtze River

马鞍山河段是长江下游典型的顺直分汊河段,河段内洲滩众多,消长频繁,是长江下游重点研究治理河段之一。基于历年实测资料,详细分析了马鞍山河段滩群演变特征及其联动效应,进而揭示了影响马鞍山河段演变的主要因素。研究表明:马鞍山河段内滩群以此消彼长的形式发生着局部格局的调整,随着江心洲左缘冲刷后退、心滩和下何家洲冲刷下移,牛屯河边滩淤积展宽、下延。上游河势调整以及来水来沙条件变化是马鞍山河段洲滩演变的外驱动力,河道宽而顺直的平面形态、滩群演变的互馈机制则是其内驱动力。

The Ma’anshan River reach is a typical straight distributary reach in the lower stream of the Yangtze River with multiple bars which emerge and submerge frequently. It is an important reach to be studied and harnessed in the lower Yangtze River. The evolution characteristics and coupling effects of the bars were analyzed in detail based on field surveying data to reveal the main factors determining the evolution patterns of the Ma’anshan Reach. The results indicate that the emerging and submerging pattern changes locally. With the left edge scouring and receding of the central bar and the scouring and moving down of the Xintan Bar,silting,widening and moving down occurred for the side beach of Niutunhe Bar. Upstream river regime adjustment and flow-sediment condition change were the external driving forces of the beach and bar adjustments. Broad and straight river plane form and interaction among the bars were the internal driving forces.