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Development of Drought Index based on Streamflow for Monitoring Hydrological Drought

수문학적 가뭄감시를 위한 하천유량 기반 가뭄지수 개발

  • 유지영 (한양대학교 공학대학 건설환경공학과) ;
  • 김태웅 (한양대학교 공학대학 건설환경공학과) ;
  • 김정엽 (한강홍수통제소 수자원정보센터) ;
  • 문장원 (한국건설기술연구원 수자원.하천연구소)
  • Received : 2017.04.07
  • Accepted : 2017.05.19
  • Published : 2017.08.01

Abstract

This study evaluated the consistency of the standard flow to forecast low-flow based on various drought indices. The data used in this study were streamflow data at the Gurye2 station located in the Seomjin River and the Angang station located in the Hyeongsan River, as well as rainfall data of nearby weather stations (Namwon and Pohang). Using streamflow data, the streamflow accumulation drought index (SADI) was developed in this study to represent the hydrological drought condition. For SADI calculations, the threshold of drought was determined by a Change-Point analysis of the flow pattern and a reduction factor was estimated based on the kernel density function. Standardized runoff index (SRI) and standardized precipitation index (SPI) were also calculated to compared with the SADI. SRI and SPI were calculated for the 30-, 90-, 180-, and 270-day period and then an ROC curve analysis was performed to determine the appropriate time-period which has the highest consistency with the standard flow. The result of ROC curve analysis indicated that for the Seomjin River-Gurye2 station SADI_C3, SRI30, SADI_C1, SADI_C2, and SPI90 were confirmed in oder of having high consistency with standard flow under the attention stage and for the Hyeongsan River-Angang station, SADI_C3, SADI_C1, SPI270, SRI30, and SADI_C2 have order of high consistency with standard flow under the attention stage.

본 연구에서는 하천의 갈수관리를 위한 기준유량과 가뭄지수와의 일관성 분석을 수행하기 위해서, 국토교통부 홍수통제소에서 고시한 37개 갈수예보 관리지점 중 섬진강 수계의 구례2지점과 형산강 수계의 안강지점을 대상으로 하여 관측된 일별 유량 자료를 구축하였으며, 더불어 인근 기상관측소 남원지점과 포항지점의 강우량 자료를 활용하였다. 본 연구에서는 하천 유량자료를 기반으로 한 수문학적 가뭄상황을 재현해줄 수 있는 유량누가가뭄지수(SADI)를 개발하였다. SADI는 유량패턴의 변동시점(Change-Point) 분석을 통해 가뭄절단수준을 결정하였고, 또한 감소계수 추정을 위해 핵밀도함수를 이용하였다. 이처럼 계산된 SADI는 표준유출지수(SRI), 표준강수지수(SPI)와 비교되었으며, 이 중 SRI와 SPI는 30일, 90일, 180일, 270일 시간단위에 대한 가뭄지수를 모두 산정한 후, ROC 곡선 분석을 이용하여 갈수예보 기준유량과 일관성이 가장 높은 시간단위를 최종 결정하였다. 갈수예보 지점의 관심단계 예보기준유량을 기반으로 하여 다양한 가뭄지수와의 ROC 곡선 분석을 실시한 결과, 섬진강 수계의 구례2지점은 SADI_C3, SRI30, SADI_C1, SADI_C2, SPI90의 순으로 갈수예보의 정확도가 높은 것으로 나타났다. 또한, 형산강 수계의 안강지점은 SADI_C3, SADI_C1, SPI270, SRI30, SADI_C2의 순으로 갈수예보의 정확도가 높은 것으로 나타났다.

Keywords

References

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