Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
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Evaluation of Drought Index Based on the Calculation of Potential Evapotranspiration

잠재증발산량 계산에 따른 가뭄지수 평가

  • Kidoo Park (Climate Crisis Emergency Management Institute, Kyungpook National University) ;
  • Innkyo Choo (Department of Advanced Science and Technology Convergence, Kyungpook National University) ;
  • Beomgu Kim (Department of Advanced Science and Technology Convergence, Kyungpook National University) ;
  • Shiksha Bastola (Department of Advanced Science and Technology Convergence, Kyungpook National University) ;
  • Seungjin Maeng (Department of Agricultural and Rural Engineering, Chungbuk National University) ;
  • Beomseok Kim (Korea Rural Community Corporation Audit & Inspection Office) ;
  • Younghun Jung (Department of Advanced Science and Technology Convergence, Kyungpook National University)
  • Received : 2024.10.09
  • Accepted : 2024.10.23
  • Published : 2024.11.01
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Abstract

In this study, data from the Gwangyang Automated Synoptic Observing System (ASOS) meteorological observatory were utilized for drought assessment. Drought occurrence days were evaluated using the Precipitation-based Standardized Precipitation Index (SPI) and two types of Standardized Precipitation Evapotranspiration Index (SPEI) (SPEI_Thornthwaite and SPEI_Penman-Monteith), considering precipitation and evapotranspiration. The SPI and SPEIs yielded generally similar quantitative results for drought occurrence days. However, the SPEI_Penman-Monteith, which uses the physically-based Penman-Monteith method for evapotranspiration estimation, showed a higher number of drought days compared to the SPI_Thornthwaite. The amount of evapotranspiration by the Penman-Monteith method had high seasonal variability and high moisture loss, while the amount of evapotranspiration by the Thornthwaite method had low variability and low moisture loss. Consequently, the SPEI_Thornthwaite had a higher correlation with the SPI compared to the SPEI_Penman-Monteith. Since the SPEI_Penman-Monteith index can more accurately calculate the amount of water loss caused by the hydrological circulation, more reasonable results are derived in calculating the number of drought occurrence days. However, due to the lack of sufficient high-quality meteorological data at ASOS observatories, the Penman-Monteith method may be difficult to apply. In such cases, the SPEI_Thornthwaite, estimating evapotranspiration based solely on monthly average temperature, can be used as an alternative.

본 연구에서는 광양 지역의 가뭄 평가를 위해 광양 ASOS(Automated Synoptic Observing System) 기상관측소 자료를 활용하였다. 강수량 기반의 SPI와 강수량 및 증발산 손실을 고려한 두 가지 유형의 SPEI(SPEI_Thornthwaite 및 SPEI_Penman-Monteith)를 사용하여 가뭄 발생일수를 평가하였다. 광양 기상관측소의 SPI와 SPEI에 의해 산정된 가뭄 발생일수는 대체로 유사한 정량적 결과를 도출하였다. 그러나 물리적 기반의 Penman-Monteith 방법을 사용하는 SPEI_Penman-Monteith 지표는 SPI_Thornthwaite 지표에 비해 가뭄 발생일수가 더 높게 평가되었다. Penman-Monteith 방법에 의해 산정된 증발산량은 계절 변동성이 크고 수분 손실량도 큰 반면, Thornthwaite 방법에 의한 증발산량은 변동성이 작고 수분 손실량도 작게 평가되었다. 그 결과 SPEI_Penman-Monteith 지표에 비해 SPEI_Thornthwaite 지표가 SPI 지표와 더 높은 상관관계를 보였다. 물리적 모형 기반의 SPEI_Penman-Monteith 지표는 물의 순환에 따른 수분 손실량을 더 정확하게 산정할 수 있기 때문에 가뭄 발생일수 산정에서 더 합리적인 결과가 도출된다. 하지만 대부분의 ASOS 기상관측소에서는 일사량과 같은 고품질 기상자료가 충분하지 않기 때문에 Penman-Monteith 방법을 적용하기는 어렵다. 따라서, 이런 경우에는 월평균 기온만으로 증발산량을 추정할 수 있는 SPEI_Thornthwaite 지표가 가뭄지수 산정의 대안으로써 활용할 수 있다.

Keywords

Acknowledgement

본 연구는 환경부의 재원으로 한국환경산업기술원의 가뭄 대응 물관리혁신기술개발사업 의 지원을 받아 연구되었습니다(2022003610003).

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