长江下游黑沙洲南水道演变特征分析

针对三峡水库蓄水及整治工程后长江下游分汊河段的演变问题,收集了黑沙洲水道1960—2005年的实测分流、分沙比和2004—2012年共31个测次的地形图,应用HEC-RAS模型分析了黑沙洲水道整治工程前后分流比的变化,应用地理信息系统(GIS)和数字高程模型(DEM)分析了整治工程前后南水道浅滩面积、体积及位置的变化。研究分析表明:三峡水库蓄水后的2004—2009年,黑沙洲南水道的浅滩总体表现为冲刷,但在年内仍然保持着"洪淤枯冲"的基本冲淤特性;2009年整治工程部分改善了南水道的航行条件,但整治工程中潜坝的设置减小了南水道中枯水期分流比,不利于中枯水期南水道的冲刷,整治工程后南水道的浅滩演变呈淤积趋势。本项研究成果可为航道维护和整治工程设计提供借鉴参考。

Evolution characteristics analysis of Heishazhou southern-waterway of the lower Yangtze River

In order to study the riverbed evolution characteristics and trends of the braided waterway downstream of the Yangtze River after impoundment of the Three Gorges hydroproject and construction of the regulation works, the measured flow and sediment diversion ratio from 1960 to 2005 and a total of 31 topographic maps from 2004 to 2012 are collected in the Heishazhou waterway studies. A one-dimensional hydraulic model of HEC-RAS is used to calculate and analyze the flow diversion ratio of the Heishazhou southern waterway before and after regulation works. The geographic information system (GIS) and a digital elevation model (DEM) are used to calculate and analyze the changes in the area, volumes and location of the shoal of the Heishazhou southern waterway. The analysis results show that the shoal of the Heishazhou southern waterway was scoured from 2004 to 2009; and the shoal still keeps the characteristics of erosion and deposition after the impoundment of the Three Gorges hydroproject. The flow diversion ratio of the southern waterway during the low-water season is reduced by 1.5% and the shoal evolution trends toward deposition after completion of the regulation works. The research findings can be used as a reference for design and maintenance of the similar waterway works.