High Performance Flood Simulation with Precise Digital Terrain Model

• Main Authors: WU, CHENG-HSUAN, 吳承軒
• Other Authors: CHANG, CHE-HAO
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/4uctde

碩士 === 國立臺北科技大學 === 土木工程系土木與防災碩士班 === 107 === Today, high Performance Flood Simulation have developed in many cities. In order to hourly forecast flooding for next three hours, the resolution of the Digital Elevation Model (DEM) in Flood module are usually 20m and 40m. With the evolution of computing devices, there is a tendency for Flooding Simulation with precision terrain. Hydro Digital Elevation Model (HyDEM) has been proposed to consider detailed terrain. Objects affecting water flooding on the ground will be retained, while those allowing water to penetrate will be shown as the elevation of the ground to make HyDEM much closer to reality. However, flooding simulation often requires lengthy computing time when using precise terrain, HyDEM has not been applied to real-time flood forecasting. Balancing computing time and flooding forecasting timeliness with limited hardware resources and software limitation is important. In the 2D flood module, the amount of grids, which is influenced by calculation area and grid resolution, is a key factor in computing time. In this study, the accuracy of the simulation is taken as a priority through adjusting calculating area to control the number of grids. Instead of using high resolution DEM in the entire basin, partial high resolution DEM in high risk area combine with low resolution DEM, will reduce lot of computation and save computing time. In this study, adaptive partitioning algorithm was proposed for improving simulation accuracy by the combination of high and low resolution of grids. Size of precise digital terrain area was resolved by changing threshold value, which is determined simulating flooding frequency and depth, to make computing time within a limited time. Simulating numerous flooding with flooding module in Dongmen River Basin in Taoyuan City, high-risk flooding areas are defined. With the multi-grid function which was used in high-risk flooding areas in SOBEK, configuration of precise terrain which could keep the computing time within the forecasting timeliness would be found out. The results show that the computing time vary with threshold value, indicating that this method can be used to find the appropriate terrain configuration in different situation.