MODELLING URBAN FLOODPLAIN INUNDATION WITH DIFFERENT SPATIAL RESOLUTION AND MODEL PARAMETERISATION

摘要

One-dimensional (1D) hydrodynamic models have been used as a standard industry practice for urban flood modelling work for many years. More recently, however, model formulations have included a 1D representation of the main channels and a 2D representation of the floodplains. Since the physical process of describing exchanges of flows with the floodplains can be represented in different ways, the predictive capability of different modelling approaches can also vary. Researches have shown that with the availability of high resolution DEMs derived from airborne LiDAR, these models can theoretically be routinely parameterized to represent considerable topographic complexity, even in urban areas where the potential exists to represent flows at the scale of individual buildings. However, computational constraints on the use of fine resolution DTM for 2D urban flood modeling require model dicritisations at scale well below those achievable with LiDAR and thus unable to make optimal use of this emerging data stream. The present paper explores effects of some of the key issues that concern urban flood modelling work. Impacts from applying different model schematization, geometry and parameter values were investigated. It discusses how different Digital Terrain Model (DTM) resolution, presence of different features on DTM such as roads and building structures and different friction coefficients affect the simulation results. In addition, this paper discusses an approach that aims to capture small scale urban features which are presented in fine resolution data as we try to move from sub-grid scale to coarse resolution of 2D models.