应对畜禽养殖跨界污染的流域水资源生态补偿量研究——以国家生态补偿示范区九洲江流域为例

Ecological compensation for cross-boundary pollution control of livestock and poultry:a case study of Jiuzhou River Basin in national ecological compensation demonstration area

生态补偿标准研究是国内外流域生态补偿领域研究的热点话题。以国家生态补偿试点区九洲江流域为例,围绕生猪养殖跨界污染问题,以COD、TP、TN为目标控制污染物,计算水环境容量约束下的污染物削减目标量。设置禁养区关闭拆迁养猪场、高架床养殖模式改造、养殖粪尿废水集中处理3种典型控制方式,以污染物削减目标量为约束条件,构建线性规划模型求算不同治理情景下用于水污染控制的投入成本,从而求算最小生态补偿量。在此基础上以取水量、供水量、GDP为主要约束条件,建立中央、广东、广西政府生态补偿投入资金分担比例模型,明确中央、广东及广西政府各自分摊的生态补偿金额。此外,考虑到模型参数不确定性对生态补偿量的影响,对模型参数进行了蒙特卡罗模拟和灵敏度检验,求算高架床养殖容积比(k1)、限养区污水入河系数(k2)、高架床养殖模式日排水量(k3)及传统养殖模式日排水量(k4)不确定条件下生态补偿量的所有可能值及模型参数方差贡献率。结果显示:(1)在90%保证率水质达标下,流域水环境COD、TP、TN污染物削减总量目标分别为378752.98 t、2161.60 t和13951.70 t;(2)基于成本核算法得到生态补偿量为15.03亿元,中央、广西、广东政府分摊金额分别为3.76、3.31、7.96亿元;(3)95%置信水平下,两种情景下生态补偿量置信区间分别为[12.51亿元,17.42亿元]、[9.34亿元,21.93亿元];(4)利用参数灵敏度分析得到情景一生态补偿策略下模型参数k1、k2、k3方差贡献率分别为79.50%、18.90%、1.60%,情景二生态补偿策略下模型参数k2、k4方差贡献率依次为88.80%和11.20%。

Research on ecological compensation standard is a challenging topic in the field of river basin management.We estimated the cross-boundary pollution caused by pig breeding in Jiuzhou River Basin as a case study,and calculated the total amount of pollutant reduction based on pollutants control targets of COD,TP,and TN.In the estimation process,we set up three typical control scenarios,which included:closing pig farms in forbidden breeding areas,transforming bed breeding mode,and central treating of wastewater.Considering the pollutant reduction target as the principal constraint,a linear programming model was conducted to calculate the input cost of water pollution control under different treatment scenarios;we also modelled the minimum ecological compensation based on these scenarios.Taking the water consumption,water supply and GDP as the main constraints,we established a compensation analysis with the certain proportion of investment from central government,local government of Guangdong and Guangxi province;therefore,the ecological compensation amount of each side was determined based on their investment.In this research,Monte Carlo simulation and sensitivity analysis was applied to estimate the uncertainty of parameters while modelling compensation.All possible values and variance contribution rates to ecological compensation under uncertain model parameters were calculated,these parameters included breeding volumetric ratio(k1),wastewater discharge to river basin in forbidden zone(k2),and daily wastewater discharge amount with loft-bed(k3)and daily wastewater discharge amount under traditional breeding case(k4).Our results show that:(1)the reduction amount of total pollutants for COD was 378752.98 t,2161.60 t for TP reduction and 13951.70 t for TN reduction under 90%guarantee rate of water quality standard;(2)total amount of ecological compensation was 1.503 billion based on the cost accounting method,and the allocation amount of the central government,local government of Guangxi and Guangdong province was 376 million,331 million and 796 million,respectively;(3)under the confidence intervals level of 95%,the ecological compensation values in two different scenarios were calculated as 1.25—1.74 billion and 0.93—2.19billion.(4)refering to the sensitive analysis of parameters,the variance contribution rates of parameters k1,k2 and k3 was 79.50%,18.90%and 1.60%,separately in scenario 1,and 88.80%of parameter k2 and 11.20%for 44 in scenario 2.