Design of flood-season redefinition and adaptive rule curves for Korea's multipurpose dams under climate change

Seokhwan Hwang; Narae Kang; Jung Soo Yoon

doi:10.3741/JKWRA.2026.59.9.1099

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2026 Vol.59, Issue 9 Preview Page Next Page

Design of flood-season redefinition and adaptive rule curves for Korea's multipurpose dams under climate change 기후변화 대응 다목적댐 홍수기 재설정과 적응형 Rule Curve 설계

30 September 2026. pp. 1099-1113

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Abstract

Korea's flood-season operating window for multi-purpose dams has been fixed at 92 days (21 June-20 September) for decades. Yet only about 76% of extreme-precipitation days (days with daily rainfall at or above the per-station 95th percentile of wet days (≥1 mm), Q₀.₉₅) now fall within this window, so roughly one event in four occurs outside it. Integrating KMA ASOS daily precipitation (61 stations, 1973-2024) and SSP climate scenarios, this study analyses the mismatch along temporal, spatial, and probabilistic axes. Annual maximum daily precipitation shows a marginally significant increasing trend (Mann-Kendall p ≈ 0.07, yet a field-significant signal with 50 of 61 stations increasing); the September-October share of extreme-precipitation days rose from 16% (1991-2010) to 23% (2011-2024) (Wilcoxon p < 0.001); and the share of extreme-precipitation days (2011-2024) captured within the window varies by basin, from 86% (Han) to 70% (Yeongsan), so more vulnerable southern basins have proportionally more extreme days falling outside the flood season. We argue the remedy is not a longer fixed window but a shift away from the fixed-boundary paradigm, and propose an integrated policy of staged temporal extension (110/118/129 days), regional differentiation, and a five-layer adaptive Rule Curve. Under an illustrative cost-benefit analysis, benefits exceed costs several-fold at the central estimate, and the 30-year net present value remained positive across every discount-rate and benefit combination examined here, as well as under the eight-variable tornado and adverse composite-stress tests. The contribution is not a specific monetary figure but the finding that, within the ranges examined, redefining the flood season yields net benefits.

Keywords

Multi-purpose dam

Adaptive rule curve

Climate-change adaptation

Extreme precipitation

Cost-benefit analysis

한국 다목적댐의 홍수기는 6월 21일부터 9월 20일까지 92일로 수십 년간 고정되어 왔다. 그러나 오늘날 극한강수일(지점별 습일(≥1 mm) 일강수량의 상위 5%, 즉 관측기간 전체로 산정한 95백분위수 Q_0.95 이상인 날) 가운데 약 76%만이 이 기간에 포함되어, 전체의 약 4분의 1이 홍수기 밖에서 발생한다. 본 연구는 기상청 ASOS 일강수(61개소, 1973~2024), SSP 기후시나리오를 통합하여 이 어긋남을 시간·공간·확률의 세 축으로 분석하였다. Mann-Kendall 검정 결과 연 최대 일강수량은 한계적으로 유의한 증가 추세를 보였으며(전국 평균 p ≈ 0.07, 61개 중 50개 지점이 증가하는 field-significant 신호), 9~10월 극한강수일 비율은 16%(1991~2010)에서 23%(2011~2024)로 유의하게 상승하였다(Wilcoxon p < 0.001). 홍수기 안에 드는 극한강수일의 비율(2011~2024)은 권역마다 달라, 한강은 86%인 반면 영산강은 70%에 그쳐, 회복력이 낮고 포함률도 낮은 남부 권역(영산강·섬진강)일수록 극한강수일이 홍수기 밖에서 발생하는 비율이 컸다. 이에 본 연구는 더 긴 고정 기간이 아니라 고정경계 패러다임 자체의 전환, 곧 홍수기 재설정을 제안하며, 단계적 시간 확장(110·118·129일), 권역 차등화, 5계층 적응적 Rule Curve를 통합한 정책을 제시한다. 예시적 비용·편익 분석에서 편익은 중심 추정에서 비용을 여러 배 웃돌았고, 본 연구에서 검토한 할인율(3.0·4.5·5.5%)·편익 정의(보수·중심) 범위와 8변수 토네이도·복합 스트레스 검정 내에서 30년 순현재가치(NPV)는 양(+)으로 유지되었다. 본 연구의 기여는 특정 금액의 제시가 아니라, 검토한 가정 범위에서 홍수기 재설정이 순편익을 발생시킴을 확인한 데 있다.

키워드

다목적댐

적응적 Rule Curve

기후변화 적응

극한강수

비용·편익 분석

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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 : 59
No :9
Pages :1099-1113
Received Date : 2026-07-09
Revised Date : 2026-07-20
Accepted Date : 2026-07-21
DOI :https://doi.org/10.3741/JKWRA.2026.59.9.1099

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

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