Assessment on Methodology for Predicting Flood Discharges in Creeks

Abstract

As the small public facilities established in the early stages of economic development are at increased risk of disasters due to aging, the Ministry of the Interior and Safety established the “Law of Safety Management on Small Public Facilities” and provided guidelines for reducing vulnerabilities and damages. In this study, the applicability of the Clark unit hydrograph method and a rational formula, which are methods suggested in the guidelines for predicting flood discharges, are evaluated. For the evaluation, three creek basins located in urban, agricultural, and mountainous areas are selected as test watersheds, and the measured flow discharges of small streams downstream of the creeks are determined using the area ratio flow method. The evaluation results show that, for all three creeks, the peak flood discharges predicted using both the Clark unit hydrograph method and the rational formula are greater than those determined using the area ratio flow method ; therefore, the first two methods can be used to predict flood discharges in creeks to ensure safety. However, for a more precise verification of flood discharges and for selecting optimal methods, continuous investigations are required for measuring the hydrological and hydraulics data of the creek and obtaining characteristic information regarding watersheds and channels.