平原河网地区双向生态补偿机制与核算方法

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.