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An analysis of effects of seasonal weather forecasting on dam reservoir inflow prediction

장기 기상전망이 댐 저수지 유입량 전망에 미치는 영향 분석

  • Kim, Seon-Ho (Department of Civil & Environmental Engineering, Sejong University) ;
  • Nam, Woo-Sung (National Drought Information Analysis Center, K-water corporation) ;
  • Bae, Deg-Hyo (Department of Civil & Environmental Engineering, Sejong University)
  • 김선호 (세종대학교 건설환경공학과) ;
  • 남우성 (한국수자원공사 국가가뭄정보분석센터) ;
  • 배덕효 (세종대학교 건설환경공학과)
  • Received : 2019.05.21
  • Accepted : 2019.06.08
  • Published : 2019.07.31

Abstract

The dam reservoir inflow prediction is utilized to ensure for water supply and prevent future droughts. In this study, we predicted the dam reservoir inflow and analyzed how seasonal weather forecasting affected the accuracy of the inflow for even multi-purpose dams. The hindcast and forecast of GloSea5 from KMA were used as input for rainfall-runoff models. TANK, ABCD, K-DRUM and PRMS models which have individual characteristics were applied to simulate inflow prediction. The dam reservoir inflow prediction was assessed for the periods of 1996~2009 and 2015~2016 for the hindcast and forecast respectively. The results of assessment showed that the inflow prediction was underestimated by comparing with the observed inflow. If rainfall-runoff models were calibrated appropriately, the characteristics of the models were not vital for accuracy of the inflow prediction. However the accuracy of seasonal weather forecasting, especially precipitation data is highly connected to the accuracy of the dam inflow prediction. It is recommended to consider underestimation of the inflow prediction when it is used for operations. Futhermore, for accuracy enhancement of the predicted dam inflow, it is more effective to focus on improving a seasonal weather forecasting rather than a rainfall-runoff model.

장기 기상전망 기반 댐 유입량 전망은 가뭄 대비, 용수 공급 관리 등에 활용성이 높다. 본 연구에서는 국내 7개 다목적댐 유역에 대해 유입량 전망을 수행하고 장기 기상전망 정확도가 댐 유입량 전망 정확도에 미치는 영향을 분석하였다. 강우-유출 모델의 입력자료로 활용된 장기 기상전망 자료는 기상청 GloSea5의 과거재현자료(hindcast) 및 미래전망자료(forecast)를 활용하였다. 강우-유출 모델은 다양한 특성을 가지고 있는 TANK, ABCD, K-DRUM, PRMS를 활용하였다. 댐 유입량 전망 정확도는 과거재현기간(1996~2009)과 미래전망기간(2015~2016)에 대하여 평가하였다. 댐 유입량 전망 평가결과 전망값은 관측값에 비해 과소추정하는 경향을 보였으며, 매개변수 검보정이 적절히 수행된 강우-유출 모델은 댐 유입량 전망 정확도에 미치는 영향이 거의 없는 것으로 나타났다. 반면 장기 기상전망 자료, 특히 강수량은 댐 유입량 전망 정확도에 매우 큰 영향을 미치는 것으로 나타났다. 현업에서 댐 유입량 전망 자료 활용시 과소추정하는 경향을 고려하여 활용할 필요가 있다. 향후 댐 유입량 전망 정확도 개선은 강우-유출 모델 보다 장기 기상전망의 강수량 정확도 향상을 위주로 수행할 필요가 있다.

Keywords

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Fig. 1. Study area

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Fig. 2. Schematic diagram of study procedure

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Fig. 3. Inflow prediction results of chungju dam (HCST)

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Fig. 4. Inflow prediction results of chungju dam (FCST)

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Fig. 5. Relative error of dam inflow prediction

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Fig. 6. Comparison between meteorological variable and dam inflow

Table 1. Characteristics of study area

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Table 2. Characteristics of rainfall-runoff models

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Table 3. Statistics of dam inflow prediction

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Table 4. Correlation coefficient of meteorological variables and dam inflow

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