基于多目标机器学习模型的城市内涝快速模拟研究

Fast Simulation of Urban Waterlogging Based on Multi-Objective Machine Learning Model

近年来频发的城市暴雨内涝灾害已给国家造成了严重的经济损失和人员伤亡。内涝数值模拟是灾害预警预报及防控的一种重要手段, 然而传统的数值物理模型存在计算效率低下的缺点, 难以满足暴雨内涝实时模拟和预警预报需求。为此, 本研究结合具有物理机制的耦合雨洪模型和机器学习算法各自的优势, 提出基于多目标机器学习算法的城市暴雨内涝淹没水深快速模拟的方法, 分别探讨了K近邻 (KNN) 、多目标随机森林 (MORF) 、极端梯度提升 (XGBoost) 及其集成模型的预测性能, 结果表明: (1) 基于SWMM和LISFLOOD-FP构建的耦合雨洪模型在研究区暴雨内涝模拟中具有良好的适用性, 在此基础上共生成了70种包含不同特征的“暴雨内涝”数据库; (2) KNN、MORF、XGBoost及其集成模型的水深预测效果均较好, 皮尔逊相关系数 (PCC) 值均达0. 812以上, 平均绝对误差 (MAE) 均在6. 9cm以下, 均方根误差 (RMSE) 不超过0. 116; KNNMORF-XGBoost集成模型的总体效果最好, 其MAE、PCC和RMSE的平均值分别为2. 4cm、0. 965和0. 043; (3) 所构建的多目标机器学习预测模型除了预测精度高外, 其预测速度极快, 水深模拟效率比耦合雨洪模型提升20倍以上。本研究可为机器学习在城市暴雨内涝快速模拟方面提供一种新思路, 对内涝灾害的预警预报具有重要价值。

The frequent occurrence of urban waterlogging disasters induced by rainstorm has recently caused serious economic losses and casualties in China. Numerical simulation of waterlogging is an important tool for disaster prewarning and forecasting as well as disaster prevention and control; however, the traditional numerical physical models have the disadvantage of low computational efficiency, which makes it difficult to meet the demand for real-time simulation and real-time early warning and forecast. To this end, this study combines the respective advantages of coupled rainstorm-flood models with physical mechanisms and machine learning algorithms, and proposes a rapid prediction and simulation method for inundated depth of urban waterlogging based on multi-objective machine learning algorithms. The forecasting performances of K-Nearest Neighbors (KNN) , Multi-Objective Random Forest (MORF) , Extreme Gradient Boosting (XGBoost) and their integrated models are discussed, respectively. The results show that: (1) The coupled rainstorm- flood model based on SWMM and LISFLOOD-FP has good applicability in the simulation of urban waterlogging induced by rainstorm in the study area. On this basis, the database with a total of 70 scenarios of rainstorm-inundation with different characteristics were generated. (2) The KNN, MORF, XGBoost and their integrated models all have good results in predicting water depth, with Pearson correlation coefficient (PCC) values all above 0. 812, mean absolute error (MAE) below 6. 9 cm, and root-mean-square error (RMSE) less than 0. 116. The KNN-MORF-XGBoost integrated model has the best overall results, with the average values of MAE, PCC and RMSE reaching 2. 4cm, 0. 965 and 0. 043, respectively. (3) In addition to the high prediction accuracy, the prediction speed of the constructed multi-objective machine learning prediction model is extremely fast, and the water depth simulation efficiency is more than 20 times higher than that of the coupled rainstorm-flood model. This study can provide a reference for the application of machine learning in the rapid simulation of urban waterlogging induced by rainstorm, which is of great value for the early warning and forecast of urban waterlogging disaster.