The Delft3D model was used to simulate the flooding process on floodplains of the Lower Yellow River, and the flood disaster parameters such as flooding range and flooding depth were statistically calculated from the model. The process of giving the flood risk’s spatial distribution of the plains includes dividing the hazard-vulnerability units and calculating the hazard and vulnerability of each unit according to the topography and flood-control measures. The United Nations risk assessment index system is used to give out the spatial distribution of the flood risk for each inundation unit. The results show that the relationship between flood risk and flood scenarios response across the study area can be divided into three categories. About 50% of the plain are under “simultaneous flooding and risks”, which means the flood risk level generally varies with the flood scenario. 39.7% of the plains own the trait of “low flooding frequency leads to giant risks”, and for the unit of this category basically has the extreme risk even for the 10-year frequency floods. 11.67% of the plain are stable at a relatively low risk situation, and the flood risk is not affected by the magnitude of the flood, which is classified as “stable low risks”. In order to prevent the flood risk of the Lower Yellow River, the flooding unit of “low flooding frequency leads to giant risks” mainly distributed in Gaocun to Aishan section should give a priority to take the action, and the flood situation of once every ten years or even once every five years should be taken as the reference basis for building flood prevention measures.

利用Delft3D模型, 模拟黄河下游滩区洪水漫滩过程, 获取漫滩范围和洪水淹没水深等洪水致灾参数。基于地形和防洪条件, 划分洪水漫滩淹没单元, 参考联合国灾害风险评价指标体系, 结合对各淹没单元的危险度和易损度评估, 得到不同洪水量级下各淹没单元的洪水漫滩风险度空间分布。结果表明, 占滩区总面积近 50%的淹没单元的洪水漫滩风险等级随洪水量级的增加而稳步增加, 为“水险同期”类淹没单元; 39.7%的淹没单元在十年一遇洪水情景下呈现极高风险度状态, 即“小水大险”状态; 11.67%的淹没单元稳定地处于相对较低的风险度等级, 漫滩风险不受洪水量级影响, 为“稳定低险”类。因此, 对于黄河下游滩区洪水漫滩风险, 应当重点防范主要集中分布在高村至艾山河段的“小水大险”类淹没单元, 同时应以十年一遇, 甚至五年一遇的洪水情景作为洪水防范工程措施布设的参考依据。