清淤工程对感潮河网地区防洪排涝的影响及工程方案研究

The Influence of Desilting Engineering on Flood Control and Drainage in Tidal River Network Area and Study on Engineering Proposal

摘要: 我国东部沿海地区属淤泥质海岸，海域来沙丰富，大部分入海河口及上游感潮河流均存在不同程度的淤积问题，河道淤积易造成过流断面缩小、航深变浅、城市景观不和谐，给防洪、航运及生态环境造成极大影响。本文以宁波三江河道(奉化江、余姚江、甬江)为例，通过对河道水沙特性、河床演变特征及淤积机理方面的研究，以防洪排涝和城市景观为目标，拟定不同的清淤方案，运用流域水文模型计算不同工况下清淤工程的实施效果，在此基础上经综合比选确定清淤工程方案，为三江河道治理提供依据。研究成果表明，清淤工程可减少干流高水位持续时间，增加干流或沿线排涝闸的排水量，对流域行洪排涝具有一定的改善作用，但与此同时，清淤工程实施后，河道回淤不可避免，因此，清淤方案因综合考虑工程效益及回淤特性，选择对防洪排涝及城市景观有利，且清淤规模合适的方案。本文对感潮河段水沙特性、河床演变、淤积原因及治理措施等方面的研究，也可为其它类似感潮河网地区的河道整治提供参考。

Abstract: As the eastern coastal areas in China are muddy, where the sea sand is rich, siltation problems in different degrees occur in most estuaries and tidal rivers upstream of these areas. It’s easy to make flow sections narrow, channel depth shallow and urban landscape discord as deposition occurs in rivers, which have a great impact on flood prevention, shipping and ecological environment. In this paper, Ningbo Sanjiang River (Fenghua River, Yaojiang River, and Yongjiang River) was selected as an example to study the characteristics of water and sediment, the fluvial process and the deposition mechanism of the river. For the purpose of flood prevention and drainage and city landscape, different dredging schemes were proposed by using watershed hydrological model to calculate the implementation effect of the fluvial process in different conditions. On the basis of comprehensive comparison, the desilting engineering schemes were determined and provided for Sanjiang River governance. The results show that the desilting engineering can reduce the duration of the high water level, and increase the displacement of main stream or drainage gate along the river, which have an improvement effect on flood drainage of the basin. At the same time, river siltation is inevitable after the desilting engineering implementation. Therefore, the desilting scheme should consider engineering benefit and siltation characteristics, and select the scheme which is favorable for flood prevention, drainage and city landscape with suitable scale. Studies on the characteristics of water and sediment, fluvial process, deposition reasons, governance measures and so on in tidal river reach can provide a reference for other similar tidal river network area’s river regulation.