冲积河流崩岸机理、数值模拟及预警技术研究进展

冲积河流崩岸不仅影响河势稳定,而且威胁两岸堤防等重要涉水工程安全。近年来由于上游来水来沙变化及水库运用等影响,长江中下游及黄河下游河段河床冲刷,崩岸现象突出,增大了河道防洪压力。从崩岸机理、数值模拟及监测预警技术3个方面总结了冲积河流崩岸的研究进展,指出了仍待解决的几个关键问题。在崩岸机理方面,阐明了崩岸发生的力学条件及影响因素,但需深化研究各因素之间的相互作用。崩岸数值模拟方法的快速发展为崩岸预测提供了有效的技术手段,但需更为全面地考虑崩岸机理,并有效刻画河岸边界条件的沿程变化。在监测预警技术方面,通常以局部岸段的地形及水沙条件监测为主,崩岸预警等级划分指标及方法多以经验法为主,需建立统一的、完善的评估体系。

Review on Bank Erosion Processes in Alluvial Rivers:Mechanism,Modelling and Early-warning

Bank erosion processes in alluvial rivers would not only affect the channel stability in local reaches, but also cause severe damages to riparian levees. Due to the changes of incoming water and sediment condition as well as reservoir operation, the middle and lower Yangtze River and the lower Yellow River have witnessed frequent bank erosion processes, which pose great pressure on flood control management. Recent research progresses were reviewed from aspects of bank erosion mechanisms, numerical modelling, field monitoring and early-warning techniques. Some key issues to be addressed are also pointed out. In terms of bank erosion mechanism, the mechanics condition and influence factors have been well expounded by previous researches, but the interaction among such factors are to be revealed in depth. The coupling of bank erosion model with hydro-and-sediment dynamic models provides an effective technique for bank erosion prediction; yet the longitudinal variation of channel boundary (soil properties, near-bank topography, vegetation etc.) needs to be characterized more effectively and the bank erosion mechanism should be considered more comprehensively. Field monitoring in practical engineering is mainly focused on the flow and sediment conditions and the near-bank topography in some local reaches. Besides, the early-warning of bank erosion is mostly based on empirical methods; a set of systematic evaluating indicators and an improved method for classifying early-warning levels should be established.