Floods are one of the most common natural hazard having far reaching environmental implications such as soil and bank erosion, pollution of ground and surface water and landslides etc. Flood inundation modeling is frequently simulated through the numerical solution of 2D shallow water equations. These equations are a potent tool that can be used to obtain satisfactory solutions in complex riverine geometry. The usage of Sensitivity Analysis (SA) is becoming more prevalent in environmental modeling for various purposes such as uncertainty assessment, model calibration, and robust decision-making. This research is a case study of the Tous Dam break in Spain and the resultant urban flooding which was assessed for SA using the method of Morris. In all, five parameters were assessed, namely, river Manning, large roughness, time step, turbulent coefficient, and downstream boundary condition for their influence on the model output. The output, comprising depth, flood extent, bed shear stress, and time of initial inundation among others was assessed spatially as well as temporally. The temporal disaggregation revealed that the dominant factors changed position as the flood regime changed from rising to peak and then to recession. The peak flow stage had the large roughness as the most influential parameter and river Manning in the first 2 h of the rising phase while downstream boundary condition predominated during both the rising and receding phases. Curiously, temporal disaggregation revealed that the model time step, which was a marginally important parameter throughout, was able to assume the No. 1 ranking during the phase of decreasing flow i.e. the onset of the recession phase, when the model time step has to adjust from high flow velocity to slower velocities.

洪水是最常见的自然灾害之一，具有深远的环境影响，例如土壤和河岸侵蚀、地下水和地表水污染以及山体滑坡等。洪水淹没建模经常通过二维浅水方程的数值求解来模拟。这些方程是一个有效的工具，可用于在复杂的河流几何形状中获得满意的解。敏感性分析 (SA) 在用于各种目的的环境建模中变得越来越普遍，例如不确定性评估、模型校准和稳健决策。本研究是西班牙托斯大坝溃决以及由此产生的城市洪水的案例研究，并使用莫里斯方法对南澳进行了评估。总之，评估了五个参数，即曼宁河、大粗糙度、时间步长、湍流系数和下游边界条件对模型输出的影响。输出包括深度、洪水范围、河床剪应力和初始淹没时间等，并在空间和时间上进行评估。时间分解显示，随着洪水势态从上涨到峰值再到衰退，主导因素的位置发生了变化。洪峰流量阶段的影响最大的参数是大粗糙度，曼宁河在上升阶段的前 2 小时内，而下游边界条件在上升和退去阶段均占主导地位。奇怪的是，时间分解显示，模型时间步长（自始至终都是一个边际重要的参数）能够在流量减少阶段（即经济衰退阶段开始时）排名第一，此时模型时间步长必须进行调整从高流速到较慢的流速。