平原河网地区双向生态补偿机制与核算方法

针对平原河网地区地势平坦、水流流向不定、上下游关系不明确的特点，以太湖流域为例，根据“十二五”期间流域内各区域COD和NH₃-N两种污染物的削减量和削减成本，运用非线性回归获得各区域的污染物削减成本函数.根据污染物削减成本函数，以流域污染物削减总成本最小为规划目标，以区域间污染物转移量不超过30%为约束条件，构建基于单目标非线性规划方程组的流域污染物削减总成本最小化模型，求解模型获得太湖流域各区域间的污染物削减成本优化配额方案，计算行政指令配额方案与成本优化配额方案下各区域污染物削减成本的差额，以此为依据，核算生态补偿金额并确定生态补偿方向.核算结果表明，相比行政指令配额方案，太湖流域的成本优化配额方案能够节省9 897.03×104元的污染物削减总成本，根据成本优化配额方案，江苏省需要向浙江省和上海市提供10 577.86×104元的生态补偿费用，浙江省和上海市可分别获得8 909.12×104和1 668.74×104元的生态补偿费用.这种基于流域污染物削减成本最小化的生态补偿机制，根据污染物削减成本函数核算生态补偿金额并确定补偿方向，由于污染物削减成本函数有一定的变动性，因此，允许两个区域间根据成本变动情况改变补偿方向，是一种双向生态补偿机制. 

Mechanism and Computation Method of Bidirectional Ecological Compensation in Plain Rivers Network Region

In plain river network region, the flow directions of rivers are uncertain and determining the upper and lower reaches becomes difficult. It is also difficult to calculate the costs of ecological compensation and to know who is the indemnified party or indemnifying party in the area. This paper attempts to explore the mechanism and computation method of ecological compensation in the Taihu Lake Basin, which is a typical plain river network region. Based on the statistical data of the amount and the cost of COD and NH₃-N elimination during the '12th Five-Year Plan', the cost functions of COD and NH₃-N elimination of Jiangsu Province, Zhejiang Province and Shanghai Municipality located in the Taihu Lake Basin were obtained. A nonlinear programming model based on the cost functions of COD and NH₃-N elimination was then built by minimizing the cost of pollution elimination of the entire Taihu Lake Basin and making the functions subject to the constraint condition that the pollution transfer amount between districts be less than 30%. After solving the nonlinear programming equations, the pollution allocation scheme between districts that minimizes the total cost of pollution elimination (PASMC) of the entire Taihu Lake Basin was obtained. According to the PASMC, Jiangsu should pay 105.7786 million RMB to Zhejiang and Shanghai. At the same time, Zhejiang and Shanghai can receive compensation of 89.0912 million and 16.6874 million RMB respectively, because they share additional pollution from Jiangsu. However, PASMC costs 98.9703 million RMB less than the pollution allocation scheme that is made by administrative instructions (PASAI) in the entire Taihu Lake Basin. Based on the nonlinear programming model that minimizes the pollution elimination cost of the entire basin, a bidirectional ecological compensation scheme appeared. According to this scheme, the cost of ecological compensation and the indemnified or indemnifying parties are determined by the cost of pollution elimination of districts. The indemnified or indemnifying parties may switch their positions when the cost of pollution elimination changes.