Integration of fuzzy theory and multi-hierarchy comprehensive index system for health assessment of water environmental ecosystem

Abstract

Ecosystem health assessment is an effective way to cope with water pollution, environmental degradation and operation deterioration caused by human activities. Due to the complexity of water environmental ecosystem and the uncertainty of indicators, fuzzy theory improved approach for Multi-Hierarchy Fuzzy Comprehensive Evaluation (MHFCE) method is proposed in reservoir assessment. In the traditional MHFCE, the importance scale and membership degree of indicators are easily impacted by personal experience and subjective consideration, 0–1 scale is present in the process of weights calculation which avoids linguistic uncertainty when making comparison. Moreover, trapezoidal membership function and triangular membership function are presented in the process of fuzzy mapping in this method. A model application has been made in Lianhe Reservoir in Dongjiang Basin, South China, and it is concluded that reservoir assessment value belongs to the second lever of reservoir health. Overall, the improved MHFCE method provides better reservoir assessment to support reservoir management decisions with the decrease of uncertainty and increase of robustness.