Enviromental-economic Assessment On Best Management Practices In Taishitun Town Of Miyun County, Beijing

Non-point source pollution is hard to be monitored and treated due to its distinct characteristics.Best management practices(BMPs) is a combined approach to prevent non-point source pollution by engineering and management practices.It is widely applied in agricultural non-point source pollution control because of its efficiency,economic and environmental characteristics.Under China's goal of environmental,economic and social development in harmony,sound management practices should not only reach environmental goals but also have economic feasibility and optimization.So it is necessary to analyze and evaluate the cost and benefit of BMPs applied in agricultural non-point source pollution prevention.Considering the background of study area Taishitun town,which locates at upper watershed of Miyun reservoir,economic analysis was used in the evaluation system of environmental pollution control practices.Economic cost of agricultural non-point source pollution,the value of environmental benefit and economic benefit of each BMPs were evaluated by using the methodology of environmental economics.Furthermore,economic indicators were used to analyze and evaluate the cost-effect value of each practice.The results are as follows:At Taishitun Conty,non-point source pollution causes a economic loss of 4.79 million RMB,of which pollution from animal breeding contributes to 50%as the largest source and should be considered seriously;soil erosion is the second one,accounts for 28%,and 63%of soil erosion is caused by agricultural cultivation;the economic loss from domestic pollution is the least,but with great potential risk.Regarding to pollutants,the economic loss of nitrogen, phosphorus composes 82%of the total loss of non-point source pollution.The long-term impact of surface soil loss and sediment deposition can not be neglected.For 8 kinds of practices that aimed at the non-point source pollution of the study area, riparian vegetation,as an integrative pollution control practice,is the most effective.Its equivalent economic value is 1.69 million RMB.Marsh gas tank for rural families,hedgerow on sloping land,conservational cultivation and balanced fertilizer technology also have notable environmental benefits.The other three practices to change land use types contributes less in pollution control but with the long run function.All the practices are economic feasible and acceptable except returning farmland to forest, the order of practices by the economic assessment is:returning farmland on 15-25°sloping land to orchard＞hedgerow on sloping land＞conservational cultivation on 1-15°sloping land＞marsh gas tank for rural families＞returning grassland on 25°slope to forest＞returning farmland on 1-15°sloping land to contour hedgerow.Especially the first practice has more economic benefit whereas the second one has more environmental benefic,both are very suitable for the study area and worth to extend and popularize.