Estimating Regional Maximum Floods using a Runoff Data Spatial Extension Method in Ungauged Watersheds

Abstract

In this study, regional maximum floods for ungauged watersheds at the Choongju dam (CJD) were estimated using flood runoff data generated in storage function method (SFM) applications. The CJD watersheds were divided into smaller watersheds to generate runoff data for ungauged watersheds. The SFM optimized saturated rainfall (R sa) while keeping other parameters (k, p, Tl, and f 1) constant. Possible flood occurrences were estimated based on estimated runoff data and by analyzing the correlation between specific mean flooding events and regional maximum floods (Q RMF) at the CJD. Results show that, in terms of being able to estimate runoff data for CJD watersheds, the spatial extension method based on an SFM was suitable for estimating possible regional flood occurrences (NSE > 0.5). Furthermore, there are strong correlations between flood events and Q RMF (Pearson's r > 0.9); can be used to estimate regional maximum floods in the CJD watersheds.