A Risk-Based Balance Inexact Optimization Model for Water Quality Management with Sustainable Wetland System Development—A Case Study of North China

In this study, a risk-based balance inexact water resources optimization model for considering wetland ecological water demand and water quality problems, based on interval-parameter programming, fuzzy two-stage stochastic programming, and downside risk-aversion measure, is developed for regional water resources management in Nansihu Lake basin, Shangdong province, China. The developed model can tackle uncertainties described in terms of interval values and probability distributions. Moreover, risk aversion is incorporated by limiting the volatility of the expected profit through downside risk methodology, in order to limit the risk of failing to reach an income target of competitive regions in the lake basin and reflect the preference of decision makers, such that the tradeoff between system economy, ecological water demand, and income target could be analyzed. All suggested scenarios (e.g. the plausibility degree of ecological water demand and the risk level of unbalance income) are determined by management requirement. The results indicated that different water inflow and ecological-related water demand levels correspond to different water shortages and allocation schemes of different water sources, and thus lead to varied system benefit and system-failure risk. The proposed model is valuable for supporting mid-/long-term water resources management under economic, environmental, ecological, and system balance development considerations.