College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang City, Hubei Province 443002, China.
J Environ Manage. 2012 Oct 15;108:54-65. doi: 10.1016/j.jenvman.2012.04.037. Epub 2012 May 30.
Although integrated simulation and optimization approaches under stochastic uncertainty have been applied to eutrophication management problems, few studies are reported in eutrophication control planning where multiple formats of uncertainties and nonlinearities are addressed in forms of intervals and probabilistic distributions within an integrated framework. Since the impounding of Three Gorges Reservoir (TGR), China in 2003, the hydraulic conditions and aquatic environment of the Xiangxi Bay (XXB) have changed significantly. The resulting emergence of eutrophication and algal blooms leads to its deteriorated water quality. The XXB becomes an ideal case study area. Thus, a simulation-based inexact chance-constrained nonlinear programming (SICNP) model is developed and applied to eutrophication control planning in the XXB of the TGR under uncertainties. In the SICNP, the wastewater treatment costs for removing total phosphorus (TP) are set as the objective function; effluent discharge standards, stream water quality standards and eutrophication control standards are considered in the constraints; a steady-state simulation model for phosphorus transport and fate is embedded in the environmental standards constraints; the interval programming and chance-constrained approaches are integrated to provide interval decision variables but also the associated risk levels in violating the system constraints. The model results indicate that changes in the violating level (q) will result in different strategy distributions at spatial and temporal scales; the optimal value of cost objective is from [2.74, 13.41] million RMB to [2.25, 13.08] million RMB when q equals from 0.01 to 0.25; the required TP treatment efficiency for the Baisha plant is the most stringent, which is followed by the Xiakou Town and the Zhaojun Town, while the requirement for the Pingyikou cement plant is the least stringent. The model results are useful for making optimal policies on eutrophication control planning and water quality improvement in the XXB.
尽管在随机不确定性下集成模拟和优化方法已应用于富营养化管理问题，但在富营养化控制规划中，很少有研究报告涉及在综合框架内以区间和概率分布形式处理多种不确定性和非线性问题。自 2003 年中国三峡水库蓄水以来，香溪河（XXB）的水力学条件和水生态环境发生了显著变化。由此产生的富营养化和藻类大量繁殖导致其水质恶化。XXB 成为一个理想的案例研究区。因此，开发并应用了一种基于模拟的不精确机会约束非线性规划（SICNP）模型，用于在不确定性下对三峡水库 XXB 的富营养化进行控制规划。在 SICNP 中，将去除总磷（TP）的污水处理成本设定为目标函数；在约束条件中考虑了污水排放标准、河流水质标准和富营养化控制标准；在环境标准约束中嵌入了磷输移和归宿的稳态模拟模型；区间规划和机会约束方法相结合，为违反系统约束提供了区间决策变量和相关风险水平。模型结果表明，违反水平（q）的变化将导致时空尺度上不同的策略分布；当 q 从 0.01 到 0.25 时，成本目标的最优值从 2740 万元到 13410 万元；白沙厂的 TP 处理效率要求最严格，其次是下口镇和昭君镇，而平邑口水泥厂的要求最不严格。模型结果可用于制定 XXB 富营养化控制规划和水质改善的最优政策。
