Rainfall thresholds and flood warnings: A case study in New Taipei City
Journal
Computing in Civil and Building Engineering - Proceedings of the 2014 International Conference on Computing in Civil and Building Engineering
Pages
1230-1237
ISBN
9780784413616
Date Issued
2014
Author(s)
Abstract
High-intensity rainfall of short duration is triggered by mesoscale convective clouds and remains difficult to forecast with numerical forecasting models. The Water Resource Agency (WRA) in Taiwan has developed a flood alert system that has defined two levels of flood warning based on predefined rainfall thresholds in each township. The system tracks rainfall in real-time through rain gauge stations in specific locations and then issues flood warnings to the corresponding affected townships when the rainfall reaches a predefined threshold. However, the system does not account for temporal-spatial rainfall distribution and the density of rain gauge stations; because of failed alarms that can thus result, some townships are inundated during the heavy rain and typhoon season. To improve the effectiveness of the flood warning system, we have proposed a methodology utilizing data from Quantitative Precipitation Forecasts (QPFs) to examine and revise the rainfall thresholds of the WRA. This procedure has two phases: (1) assess the effectiveness of flood warnings in each township, and (2) adjust the original rainfall thresholds. Taking New Taipei City as the study case, we revised the rainfall thresholds in five townships based on the proposed methodology and rainfall data collected during the invasion of Typhoon SAOLA that attacked Taiwan from July 31 to August 3, 2012. The revised thresholds will be tested in future events to validate their effectiveness with regard to accurate flood warnings.
SDGs
Publisher
American Society of Civil Engineers (ASCE)
Type
conference paper