Regional frequency analysis using spatial data extension method : I. An empirical investigation of regional flood frequency analysis

Abstract

For the design of infrastructures controlling the flood events at ungauged basins, this study tries to find the regional flood frequencies using peak flow data generated by the spatial extension of flood records. The Chungju Dam watershed is selected to validate the possibility of regional flood frequency analysis using the spatially extended flood data. Firstly, based on the index flood method, the flood event data from the spatial extension method is evaluated for 22 mid/smaller sub-basins at the Chungju Dam watershed. The homogeneity of the Chungju dam watershed was assessed in terms of the different size of watershed conditions such as accumulated and individual sub-basins. Based on the result of homogeneity analysis, this watershed is heterogeneous with respect to individual sub-basins because of the heterogeneity of rainfall distribution. To decide the regional probability distribution, goodness-of fit measure and weighted moving averages method from flood frequency analysis were adopted. Finally, GEV distribution was selected as a representative distribution and regional quantile were estimated. This research is one step further method to estimate regional flood frequency for ungauged basins.

Regional Flood Frequency Analysis for a Poorly Gauged Basin Using the Simulated Flood Data and L-Moment Method

“…The estimated growth curves are shown in the Figure 3. The growth curves for GEV and GNO distributions were considered and compared with the result of the previous study [17]. The estimated growth curves between GEV and GNO distributions were very similar for the return period smaller than 100 years.…”

“…Rainfall data for major storms are widely available at the study basin. The L-moment method provides less bias in flood estimation and is universally applied in the literature [9][10][11][12][13][14][15][16].Use of the simulated flood data in the RFFA was previously proposed by Kim et al [17]. They applied the RFFA to AMF data generated from the storage function runoff model.…”

“…Since the RFFA that employs the spatial data extension method is based on the simulated AMF, it is important to assess the applicability of the method in the RFFA. In this study, we aim to test the spatial data extension method using a rainfall-runoff model and modeling strategy which are different from the previous study [17]. The proposed rainfall-runoff modeling strategy allowed us to generate the AMF data in a poorly gauged basin.…”

“…The estimated flood quantiles were evaluated using the AMF data observed at the outlet and one interior location in the study basin. Our results were compared to those of the previous study [17] to assess the applicability of the developed flood estimation method.…”

“…Use of the simulated flood data in the RFFA was previously proposed by Kim et al [17]. They applied the RFFA to AMF data generated from the storage function runoff model.…”