The probabilistic drought forecast based on ensemble using improvement of the modified surface water supply index

Suk Hwan Jang; Jae-Kyoung Lee; Ji Hwan Oh; Joon Won Jo

doi:10.3741/JKWRA.2016.49.10.835

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The probabilistic drought forecast based on ensemble using improvement of the modified surface water supply index Modified surface water supply index 개선을 통한 앙상블 기반 확률론적 가뭄전망

31 October 2016. pp. 835-849

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Abstract

Accurate drought outlook and drought monitoring have been preceded recently to mitigate drought damages that further deepen. This study improved the limitations of the previous MSWSI (Modified Surface Water Supply Index) used in Korea and carried out probabilistic drought forecasts based on ensemble technique with the improved MSWSI. This study investigated available hydrometeorological components in Geum river basin and supplemented appropriate components (dam water level, dam release discharge) in addition to the four components (streamflow, groundwater, precipitation, dam inflow) usedin the previous MSWSI to each sub-basin. Although normal distribution was fitted in the previous MSWSI, the most suitable probabilistic distributions to each meteorological component were estimated in this study, including Gumbel distribution for precipitation and streamflow data; 2-parameter log-normal distribution for dam inflow, water level, and release discharge data; 3-parameter log-normal distribution for groundwater. To verify the improved MSWSI results using historical precipitation and streamflow, simulated drought situations were used. Results revealed that the improved MSWSI results were closer to actual drought than previous MSWSI results. The probabilistic forecasts based on ensemble technique with improved MSWSI were performed and evaluated in 2006 and 2014. The accuracy of the improved MSWSI was better than the previous MSWSI. Moreover, the drought index of actual drought was included in ranges of drought forecasts using the improved MSWSI.

Keywords

MSWSI

Probabilistic Drought Forecast

Ensemble Technique

최근 피해가 점차 심해지고 있는 가뭄을 경감하기 위해서는 가뭄모니터링 뿐만 아니라 정확한 가뭄전망이 수행되어야 한다. 본 연구에서는 국내 기존 MSWSI의 한계점을 개선하였으며, 개선된 MSWSI를 이용하여 앙상블기반 확률론적 가뭄전망을 수행하였다. 우선 금강유역 내 존재하는 모든 수문기상인자를 조사하여 각 유역별로 기존 MSWSI에서 적용한 4개 인자(하천유량, 지하수, 강수, 댐유입량)와 적합한 인자(댐저수위, 댐방류량)를 추가 선정하였다. 두 번째로 기존에는 정규분포만을 적용하였으나 본 연구에서는 각 수문기상인자들에 적합한 확률분포를 추정하였다. 강수와 하천은 대부분 Gumbel 분포, 댐유입량, 방류량, 저수위는 2 매개변수 대수정규분포, 지하수는 3 매개변수 대수정규분포를 따르는 것으로 나타났다. 개선된 MSWSI를 과거 실측강수, 하천유량 등을 이용하여 검증한 결과 기존 MSWSI보다 개선된 MSWSI가 과거 발생한 가뭄현상을 더 잘 나타내어 개선된 MSWSI가 효용성이 있음을 확인하였다. 마지막으로 개선된 MSWSI를 이용하여 앙상블기반 확률론적 가뭄전망을 극심한 가뭄이 발생한 2006년과 2014년을 대상으로 수행하고 검증하였으며, 기존보다 개선된 MSWSI를 이용한 가뭄전망이 우수한 결과를 나타냈다. 또한 대부분의 소유역에서 실제 가뭄의 가뭄지수가 개선된 MSWSI를 이용한 가뭄전망 범위에 속하는 것으로 나타났다.

키워드

MSWSI

확률론적 가뭄전망

앙상블 기법

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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 : 49
No :10
Pages :835-849
Received Date : 2016-07-19
Revised Date : 2016-08-22
Accepted Date : 2016-08-29
DOI :https://doi.org/10.3741/JKWRA.2016.49.10.835

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

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