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Method of estimating exploitable groundwater amount considering relationship between precipitation and recharge and the variation of 10-year minimum precipitation

강수량-함양량 관계와 10년 최소강수량 변화를 고려한 지하수 개발가능량 산정 기법

  • Chung, Il-Moon (Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology) ;
  • Lee, Jeongwoo (Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology) ;
  • Lee, Jeong Eun (Department of Land, Water and Environment Research, Korea Institute of Civil Engineering and Building Technology) ;
  • Kim, Min Soo (Daelim Industrial Co. Ltd.)
  • 정일문 (한국건설기술연구원 국토보전연구본부) ;
  • 이정우 (한국건설기술연구원 국토보전연구본부) ;
  • 이정은 (한국건설기술연구원 국토보전연구본부) ;
  • 김민수 ((주)대림산업)
  • Received : 2019.04.10
  • Accepted : 2019.05.13
  • Published : 2019.06.30

Abstract

The amount of exploitable groundwater amount in Korea has been determined by multiplying the 10-year frequency low precipitation by the recharge rate. In practice, however, the interpretation of the frequency analysis of precipitation is omitted, and the value obtained by multiplying the average recharge rate by the minimum precipitation in the recent 10 years is used as the recharge amount. Therefore, the contradiction arises that the amount of precipitation to be applied is determined according to the period selection rather than the actual low precipitation by the 10-year frequency analysis. In this study, we proposed a method for estimating the exploitable groundwater amount using the recharge amount considering the moving averaged 10-year minimum precipitation and the size of precipitation. This method was applied to the Uiwang, Gwacheon and Seongnam areas and the exploitable groundwater amount was calculated and compared with the results obtained by conventional methods. As a result, it has been confirmed that if the 10-year minimum precipitation is selected in the period including the extreme drought, the problem of underestimating the exploitable groundwater amount can be overcome by using the moving average minimum precipitation.

우리나라의 지하수 개발가능량은 10년 빈도에 해당하는 갈수시의 강수량에 함양율을 곱한 값으로 정해져 왔다. 하지만 실무에서는 강수량의 빈도 해석을 생략하고 최근 10년 중 최소 강수량에 평균 함양율을 곱한 값을 개발가능량으로 사용하고 있다. 따라서 실제 10년 빈도의 갈수시 강수량이 적용되기 보다는 기간 선택에 따라 적용하는 강수량이 정해지는 모순이 발생한다. 이에 본 연구에서는 이동 10년 최소강수량 평균과 강수량의 규모를 고려한 함양량을 이용하여 개발가능량을 산정하는 방법을 제안하였다. 이 방법을 의왕 과천 성남지역에 적용하여 개발가능량을 산정하고 보편적으로 이용되고 있는 기존 방법에 의한 결과와 비교 검토하였다. 그 결과 극심한 가뭄해를 포함한 기간에서 10년 최소강수량을 선택할 경우 개발가능량이 과소하게 산정되는 문제를 이동 평균 최저 강수량을 사용함으로써 극복할 수 있는 것으로 확인되었다.

Keywords

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Fig. 1. Study area and watershed delineation

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Fig. 2. Standard watersheds and gauging stations for study area

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Fig. 3. Comparison of observed and simulated streamflows

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Fig. 4. Spatially distributed mean annual groundwater recharge rate for study area

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Fig. 5. Annual recharge according to annual precipitation

Table 1. Groundwater recharge and exploitable groundwater withdrawal for standard watersheds

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Table 2. Estimated exploitable groundwater withdrawal using precipitation-recharge relation

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Table 3. Compared results of exploitable groundwater withdrawals (using 10 year mean recharge rates)

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Table 4. Compared results of exploitable groundwater withdrawals (using regressed recharge rates)

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