降雨径流与洪水淹没模型耦合的应用研究

洪水研究包括径流与淹没两种模式。为了探究流域降雨产汇流与淹没情况、提高洪水预报精度,本研究在传统流域水文模型的基础上耦合二维水动力学模型,建立水文-水动力耦合模型。以我国吉林温德河流域为研究实例,模拟了2017年“7·13”洪水在下游口前镇所处子流域洪水淹没过程。首先对基础数据进行预处理,建立HEC-HMS水文模型并进行参数优化后,最终获得流量过程水文结果作为水动力学模型边界条件,之后建立HEC-RAS二维水动力学模型对重要子流域进行淹没模拟。耦合模型计算结果显示,水文模型经多参数优化流量模拟的NSE系数为0.988,水动力计算最大淹没水深达9.3 m相对误差为-5.2%。从泛洪模拟结果来看,子流域上游部分的农田大量被淹,淹没水深范围在0.5~2.0 m,平均流速基本在1 m/s以下。下游口前镇内最大淹没水深接近1 m,水流速度0.2 m/s至1.5 m/s,与实际的淹没情况相吻合。研究表明,所建水文水动力耦合模型模拟计算的结果准确率较高,对具有复杂水文、水力条件的流域的洪水预报具有重要的指导意义。

Application Study of Coupling Rainfall-runoff Modeling and Floodplain Inundation Mapping

Flood researches include model simulation of runoff and inundation. In order to investigate the rainfall, runoff-producing, flow concentration, and inundation in a basin and to improve the accuracy of flood forecasting, this study established a hydrological hydrodynamic coupling flood forecasting model. Two HEC software modules, HMS and RAS, were used to integrate the two-dimensional hydrodynamic model with the traditional hydrological model. Taking Wende River Basin in Jilin Province as an example, the flooding process of 2017 "7·13" flood in Wende river sub-basin is simulated. Firstly, input data was preprocessed. A HEC-HMS hydrological model was established and optimized by multi-parameter calibration. Then, the hydrographic model output were assigned as the boundary conditions of a new RAS two-dimensional hydrodynamic model, which was used to simulate the inundation of key sub-basins. The hydrological simulation provided an optimal NSE coefficient of 0.988 for the hydrograph while the two-dimensional hydrodynamic analysis provided a maximum inundation depth of 9.3 m with a relative error of -5.2%. The simulated inundation map showed that plenty of cultivated fields in the upstream area were flooded with a water depth ranging from 0.5 to 2 m, and an average flow velocity smaller than 1 m/s. In the downstream area of Kouqian Town, the maximum inundation depth was close to 1 m, and the flow velocity was from 0.2 to 1.5 m/s, which was consistent with the field measurement. The simulated results from our hydrological hydrodynamic coupling model have high accuracy. It provides a meaningful technical method for flood forecasting in basins with complex hydrological and hydraulic conditions.