Estimating design floods in ungauged watersheds through regressive adjustment of flood quantiles from the design rainfall - runoff analysis method

Byung-Seok Chae; Jin-Young Lee; Jae-Hyun Ahn; Tae-Woong Kim

doi:10.3741/JKWRA.2017.50.9.627

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Estimating design floods in ungauged watersheds through regressive adjustment of flood quantiles from the design rainfall - runoff analysis method 설계강우-유출 관계 분석법에 의한 확률홍수량의 회귀보정을 통한 미계측 유역의 설계홍수량 산정

30 September 2017. pp. 627-635

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Abstract

It is required to estimate reliable design floods for hydraulic structures in order to respond more effectively to recent climate change. In this study, differences of design floods that were estimated the flood frequency analysis (FFA) and the design rainfall-runoff analysis (DRRA) were analyzed. In Korea, due to lack of measured flood data, the DRRA method is used in practice to determine the design floods. However, assuming the design floods estimated by the FFA as true values, the DRRA method over estimated the design floods by 79%. Thus, this study proposed a practical method to estimated design flood in ungauaged watersheds through regressive adjustment of flood quantiles estimated from the DRRA method. To this end, after investigating the differences between design floods acquired from the FFA and the DRRA method, nonlinear regression analyses were performed to develop the adjustment formulas for 8 large-dam watersheds. Applying the adjustment formula, the accuracy was improved by 65.0% on average over the DRRA method. In addition, when considering the watershed size, the adjustment formula increases the accuracy by 2.1%p on average over when not considering the watershed size.

Keywords

Adjustment formula

Flood frequency analysis

Design flood

Design rainfall

최근 기후변화에 효과적으로 대응하기 위해서 신뢰성 높은 설계홍수량을 산정할 필요성이 커지고 있다. 본 연구에서는 홍수빈도해석법과 설계 강우-유출 관계 분석법으로 산정되는 확률홍수량의 차이를 분석하였다. 우리나라의 경우 관측유량 자료가 부족하여 설계홍수량을 결정할 때 설계 강우-유출 관계 분석법으로 산정된 확률홍수량을 이용하고 있다. 관측 유량 자료를 활용한 홍수빈도해석법의 결과를 참값으로 가정하여 분석한 결 과, 설계강우-유출 관계 분석법으로 산정된 확률홍수량은 홍수빈도해석법으로 산정된 확률홍수량에 비해 약 79% 과대 산정되는 것으로 나타났 다. 따라서, 본 연구에서는 설계강우-유출 관계 분석법으로 산정된 확률홍수량을 보정하는 회귀곡선식을 개발하였다. 이를 위해 우리나라 8개 댐 유역의 강우와 유량자료를 획득한 후, 비선형 회귀분석을 통하여 보정식을 제안하였다. 본 연구에서 제안한 보정식을 적용할 경우, 설계강우-유출 관계 분석법으로 산정된 확률홍수량보다 평균적으로 정확도가 약 65.0% 향상되었다. 또한, 유역의 크기를 고려하면, 유역의 크기를 고려하지 않 았을 때보다 평균적으로 정확도가 약 2.1%p 증가하였다.

키워드

빈도해석

확률강우량

확률홍수량

회귀보정식

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Information

Publisher :KOREA WATER RESOURECES ASSOCIATION
Publisher(Ko) :한국수자원학회
Journal Title :Journal of Korea Water Resources Association
Journal Title(Ko) :한국수자원학회 논문집
Volume : 50
No :9
Pages :627-635
Received Date : 2017-05-06
Revised Date : 2017-07-08
Accepted Date : 2017-07-25
DOI :https://doi.org/10.3741/JKWRA.2017.50.9.627

Journal of Korea Water Resources Association ISSN:2799-8746(Print) 2799-8754(Online) 한국수자원학회 논문집

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