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Probabilistic assessment of causal relationship between drought and water quality management in the Nakdong River basin using the Bayesian network model

베이지안 네트워크 모형을 이용한 낙동강 유역의 가뭄과 수질관리의 인과관계에 대한 확률론적 평가

  • Yoo, Jiyoung (Research Institute of Engineering & Technology, Hanyang University) ;
  • Ryu, Jae-Hee (Department of Civil and Environmental System Engineering, Hanyang University) ;
  • Lee, Joo-Heon (Department of Civil Engineering, Joongbu University) ;
  • Kim, Tae-Woong (Department of Civil and Environmental Engineering, Hanyang University)
  • 유지영 (한양대학교(ERICA) 공학기술연구소) ;
  • 유재희 (한양대학교 대학원 건설환경시스템공학과) ;
  • 이주헌 (중부대학교 건축토목공학부) ;
  • 김태웅 (한양대학교(ERICA) 건설환경공학과)
  • Received : 2021.06.08
  • Accepted : 2021.07.20
  • Published : 2021.10.31

Abstract

This study investigated the change of the achievement rate of the target water quality conditioned on the occurrence of severe drought, to assess the effects of meteorological drought on the water quality management in the Nakdong River basin. Using three drought indices with difference time scales such as 30-, 60-, 90-day, i.e., SPI30, SPI60, SPI90, and three water quality indicators such as biochemical oxygen demand (BOD), total organic carbon (TOC), and total phosphorus (T-P), we first analyzed the relationship between severe drought occurrence water quality change in mid-sized watersheds, and identified the watersheds in which water quality was highly affected by severe drought. The Bayesian network models were constructed for the watersheds to probabilistically assess the relationship between severe drought and water quality management. Among 22 mid-sized watersheds in the Nakdong River basin, four watersheds, such as #2005, #2018, #2021, and #2022, had high environmental vulnerability to severe drought. In addition, severe drought affected spring and fall water quality in the watershed #2021, summer water quality in the #2005, and winter water quality in the #2022. The causal relationship between drought and water quality management is usufaul in proactive drought management.

본 연구에서는 낙동강 유역의 수질관리에 미치는 기상학적 가뭄의 영향을 평가하였다. 3개의 가뭄지수(30일-, 60일-, 90일-표준강수지수)를 바탕으로 심한 가뭄의 발생여부를 판단하고, 생화학적산소요구량(BOD), 총유기탄소량(TOC), 그리고 총인(T-P)에 대한 목표수질 달성비율을 분석하여, 계절에 따른 중권역의 심한 가뭄 발생이 수질관리에 큰 영향을 미치는 지역을 구분하였다. 이러한 중권역에 대하여 베이지안 네트워크 모형을 이용한 가뭄-수질관리 간의 인과관계를 확률론적으로 해석하였다. 낙동강유역의 22개 중권역 중 4개의 중권역(#2005(영강), #2018(남강댐), #2021(밀양강), #2022(낙동강하구언))이 심한가뭄에 대한 수질관리에 취약성이 큰 것으로 나타났다. 또한, 봄과 가을철 수질관리에 미치는 가뭄의 영향이 가장 큰 지역은 #2021, 여름철은 #2005, 겨울철은 #2022인 것으로 나타났다. 이러한 가뭄과 수질관리 간의 인과관계에 대한 분석결과는 사전적 가뭄관리에서의 활용도가 클 것이다.

Keywords

Acknowledgement

이 연구는 2021년도 한국연구재단 기초연구사업(NRF-2020R1C1C1014636)의 지원을 받아 수행되었습니다.

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