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Exclusive correlation analysis for algae and environmental factors in weirs of four major rivers in South Korea

4대강 주요지점에서의 조류 발생인자의 배타적 상관성분석에 대한 연구

  • Lee, Eun Hyung (Dept. Environmental Engineering, Pusan National University) ;
  • Kim, Yeonhwa (Dept. Environmental Engineering, Pusan National University) ;
  • Kim, Kyunghyun (Water Environment Research Department, Water Environment assessment division, National Institute of Environmental Research, Ministry of Environment) ;
  • Kim, Sanghyun (Dept. Environmental Engineering, Pusan National University)
  • 이은형 (부산대학교 환경공학과) ;
  • 김연화 (부산대학교 환경공학과) ;
  • 김경현 (국립환경과학원 수질통합관리센터) ;
  • 김상현 (부산대학교 환경공학과)
  • Received : 2015.09.22
  • Accepted : 2015.12.28
  • Published : 2016.02.29

Abstract

Algal blooms not only destroy fish habitats but also diminish biological diversity of ecosystem which results into water quality deterioration of 4 major rivers in South Korea. The relationship between algal bloom and environmental factors had been analyzed through the cross-correlation function between concentration of chlorophyll a and other environmental factors. However, time series of cross-correlations can be affected by the stochastic structure such auto-correlated feature of other controllers. In order to remove external effect in the correlation analysis, the pre-whitening procedure was implemented into the cross correlation analysis. The modeling process is consisted of a series of procedure (e.g., model identification, parameter estimation, and diagnostic checking of selected models). This study provides the exclusive correlation relationship between algae concentration and other environmental factors. The difference between the conventional correlation using raw data and that of pre-whitened series was discussed. The process implemented in this paper is useful not only to identify exclusive environmental variables to model Chl-a concentration but also in further extensive application to configure causality in the environment.

남조류의 대번성은 특정 생물종의 감소와 물고기의 서식처를 감소하게 하는 결과를 가져와서 생태계에 상당한 교란을 가져오고 4대강의 수질을 위협하고 있다. 조류의 대번성에 영향을 미치는 인자를 해석하기 위해서 전통적으로 클로르필 a의 농도와 환경인자간의 교차상관함수를 계산하는 방식이 수행되어왔다. 교차상관함수에 사용되는 원 시계열 자료는 추계구조에 의해 영향을 받기 때문에 시계열 데이터의 추계학적인 구조를 파악하고 외부의 영향을 제거하는 선백색화 기법을 도입하였다. 이와 같은 모의과정은 모형구조의 파악, 매개변수추정, 선택된 모형의 자가진단수행등의 일련의 과정으로 진행된다. 선백색화 처리된 데이터를 이용하여 배타적 상관분석을 실시하였고 원데이터의 결과와 비교하였다. 이와 같은 과정은 조류농도 발생의 영향 인자를 구분하기 위해서도 유용한 과정이고 다른 환경인자들 사이에서의 인과성을 규명하는데도 유용하다.

Keywords

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