Rapid Flood Evaluation Systems in Taiwan Metropolitan Areas

Abstract

Hydrological issues in metropolises in Taiwan have become increasingly important because the storm water sewer systems of metropolises are frequently unable to meet the requirements of the existing and future metropolitan development. Typhoons or torrential rains that cause rainfall intensities that exceed the designed capacity of storm water sewers can result in serious flooding. The losses caused by flooding can be reduced if the areas at risk of flooding can be predicted and warnings can be issued to prompt disaster prevention and allow response units and residents to prepare before disasters occur. The primary purpose of this study is to integrate the quantitative precipitation forecasting technologies [1, 2] developed by the Taiwan Typhoon and Flood Research Institute to establish a rapid, stable, real-time, and automatic metropolitan area flood estimation system for predictive flooding analysis. The objects of this study are metropolitan areas in Taiwan with storm water sewer systems. The standard capacities of storm water sewer systems throughout Taiwan and the geographic information system (GIS) shape files are collected and compiled. Additionally, the potential flooding areas are divided into four levels (high, medium, low, and no flooding) and are compared with the rainfall warning values of the Water Resources Agency. The study combines the results of quantitative precipitation forecasts, establishes an information database (MySQL), processes Google Earth KML files, and designs a WEB GIS display interface to construct a system for estimating the flooding possibility (probability) in metropolitan areas during typhoons or torrential rains. This study subsequently employs the event of Typhoon Kalmaegi for flooding estimation and display; the estimation results are consistent with the flooding survey data, indicating that the estimations made by the flooding estimation system are correct.