Flood damage estimation for downtown Shanghai sensitivity analysis

Flood damage estimation is essential to flood risk analysis. Flood hazards, values of elements at risk and vulnerability of elements determine flood damage. However, these determinants entail uncertainties. In this study, water depth, values of elements at risk and damage function are selected as three key parameters. The local sensitivity method, which changes the value of one parameter at one time, is adopted to determine the sensitivity degrees of parameters for flood damage estimation in downtown Shanghai, China. The variance of 25% for water depth as a function of different return periods of 50,100, 200,500,1000 and 10,000 years, values of elements at risk and damage functions (piecewise function and square-root function) are uniformly taken into account in the sensitivity analysis. Sensitivity value (SV) for three parameters, which stands for the influential degree to the results of flood damage, are obtained by the largest damage being divided by the smallest damage if only changing one parameter at one time separately. The results show damage function has largest influential degree among the three parameters with SV of 2.69; while parameters of values of elements at risk (SV: 2.22) and water depth (SV: 1.81) are also significant. This suggests future research to focus first on reducing uncertainties in the flood damage functions.