基于数值模拟的黄河下游不同情景溃堤洪水特性

The analysis of embankment-break flood characteristics of the lower Yellow River based on the numerical simulation in different scenarios

通过研究黄河下游地区的溃堤洪水特性,为防洪减灾工作提供科学依据。本文以黄河下游地区的DEM,1958、1982、1996年典型历史洪水和2000年土地利用数据为模型初始输入,分4个模拟情景,依据黄河溃堤水流的特性,利用二维非恒定流模型对黄河下游不同位置决口情景下的洪水演进特性进行模拟,结果表明:洪水在演进过程中都会侵夺沿途河流行洪,进入下游后洪水会顺河归槽;在同一河段,同一年型洪水北岸不同位置溃口情景所淹没的面积大于南岸对应位置的淹没面积;黄河两岸洪泛区地理位置的差异,使两岸的洪灾程度具有区域差异;水深且流速大的洪水淹没主流区面积相对较小,水浅且流速小的非主流区面积相对较大。

Flood disaster is still a threat in the lower Yellow River due to unusual precipitation caused by the deposit of channel, the hidden danger in the embankment and unfavorable riverbed in the lower Yellow River. Study on the embankment-break flood characteristics of the lower Yellow River can afford the scientific basis for flood disaster mitigation. According to the characteristics of the embankment-break flood in the Yellow River, flood routing characteristics of embankment-break is simulated at four different locations of the lower Yellow River by inputting terrain data, typical historical flood data and land use data of the study area to two-dimensional unsteady-state flow model. Simulated results show that： Firstly, routing flood encroach the rivers on the way and enter into the rivers after reaching the lower reaches; secondly, in the same river reach, flood submerged area of north band is bigger than the corresponding location of south bank towards the same historical flood;thirdly, it is different in flood submerged degree of different regions due to the different spatial locations of floodplain. and fourthly, the area of mainstream where flood depth is high and flood velocity is quick is relatively small, but the area of non-mainstream where flood depth is low and flood velocity is slow is relatively big. Flood disaster risk in the protected zone of the embankment will be analyzed by using the results of the simulated flood in this paper, on the basis of the simulated results, the spatial pattern of the flood disaster risk in the protected zone will be analyzed in the lower Yellow River in the future. The attempt on the simulated methods and technique of the flood routing can serve as a reference to the researches in other similar regions. In this study, some factors such as the sediment, infiltration and evaporation weren＇t considered, which is a limitation to research the hydraulic characteristic of the levee-breaking flood in the Yellow River. In the succeeding simulation, the sediment should be considered to research the long-term influence on the local environment of preventing flood due to the deposit of the sediment in the riverway. At the same time the surface features should the whole way be close to the reality.