Risk grade assessment of sudden water pollution based on analytic hierarchy process and fuzzy comprehensive evaluation.

Sudden water pollution is a global environmental issue. On a large spatial scale, any pollution source may cause water pollution incidents. Dividing a large watershed into several units and giving each unit a different level would be favorable for managing sudden water pollution incidents. To scientifically divide an area into units and determine their risk grade of sudden water pollution, data of pollution sources were collected, and an area was divided into risk assessment units of sudden water pollution. The risk grade assessment was conducted following the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation method. The technology combined with the AHP and fuzzy comprehensive evaluation (F-AHP) can generate the hydrology, pollution source, natural geography, and socioeconomic characteristics of each unit and provide a risk grade evaluation. A risk grade assessment was conducted using the Yongding River as a case study. The results show that the areas with high sudden water pollution risk were mainly distributed in Shanxi Datong and Hebei Zhangjiakou. Sufficient control of pollution sources in production processes and the establishment of necessary measures to strengthen inspections should reduce the risk of sudden water pollution.