Fuzzy synthetic model for risk assessment on Haihe River basin.

A comprehensive indicator model for risk assessment and a multiple-level theoretical indicator system of the water quality-quantity-ecosystem (WQQE) for the Haihe River basin were constructed in this research. A fuzzy optimization model was used to assess risks for the four water systems of the Haihe River basin, and their risk order from high to lower risk was southern Haihe River system (SH), northern Haihe River system (NH), Tuhaimajiahe River system (TH) and Luanjiyanhai River system (LJ). The highest risk value (SH) was 0.8737. In terms of the WQQE, the secondary parameters for assessment of the four water system risks were 0.3579, 0.7226, 0.9547, and 0.5428 respectively. The results indicated that the main control factors for pollution for LJ, TH, SH and NH differed from each other and involved pollutant level, development of water resources, water flow and quality, ecosystem health and the hydrologic structure.