Available online at www.sciencedirect.com Procedia Environmental Sciences ProProcediacedia Environmental Environmental Sciences Sciences 8 (2013 (2012)11) 970 943–980 – 953 www.elsevier.com/locate/procedia The 18th Biennial Conference of International Society for Ecological Modelling Multi-level waste load allocation system for Xi‟an-Xianyang Section, Weihe River Yue Zhanga, Xiao-Yan Wanga*, Zhi-Ming Zhanga,Bing-gang Shenb aCollege of Resources, Environment & Tourism, Capital Normal University,Beijing 100048,China b Shaanxi Research and Design Institute for Environmental Science, Xi'an 710054, China Abstract Since pollutant total amount control was introduced in China in the 1980s, many researches have focused on water environmental capacity, the allocation of pollutant load, and the pollution discharge right trading. The allocation of water pollution load is the core as well as difficult point in total amount control system of water pollutants discharge. There are a series of objects for water pollutions load allocation, including water basin, the water function zoning, administrative units, sewage outlets and pollutant discharging points. For different objects of allocation, a distribution planning must be able to meet both the regional requirements and the benefits of pollutant discharging enterprises. However, it is difficult to meet the interests of various levels by one kind method of load allocation. This paper intends to establish a new multi-level load allocation system for Xi‟an-Xianyang Section, Weihe River. With large population, concentrated industrial discharging, and poor water quality, the approach needs to consider both regional development requirements and pollutant discharging point‟s economic interests. At the same time, for different objects at various levels, there is proper different distribution method according to the principles of efficiency and fairness in allocation. For regional water function zoning to administrative units, the environmental Gini coefficient analysis for regional allocation is applied in economic sphere to set up an appropriate allocation model for the optimal allocation. For administrative units to sewage outlets, optimal generation performance standard (GPS) method for enterprises allocation is used to improve the emission performance. The model‟s objective will be changed from minimum cost to greatest value. The results showed that Xi'an and Xianyang City has four counties needed to reduce the pollution load largely, respectively, because they have some prominent contradiction with the social and economic developments and the natural environment. In addition, in the key reduction region the discharge units should be cut the distribution in accordance with the ratio of distribution model. While in the maintaining present conditions regions, discharge units will have some "surplus capacity" for future emission control. This new approach for water total amount load is effective and may provide the foundation for the pollutant total amount control of Weihe River. © 20112011 Published Published by by Elsevier Elsevier B.V. Ltd. Selection and/or peer-review under responsibility of School of Environment, Beijing Normal University. * Corresponding author. Tel.: 86-10-68903968; fax: 86-10-68902332. E-mail address: [email protected] 1878-0296 © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of School of Environment, Beijing Normal University. doi:10.1016/j.proenv.2012.01.088 944 Yue ZhangY Zhang et al.et al./ Procedia/ Procedia Environmental Environmental Sciences Sciences 13 8(2012) (2011 )943 970 –– 953980 971 Keywords: Water pollution load allocation, Efficiency and fairness, Environmental Gini coefficient, Optimal generation performance standard method, Weihe River 1. Introduction In the 1980s, the ideas of pollutant total amount control were introduced to China, and triggered a lot of researches such as the calculation of water environmental capacity, the allocation of pollutant load, and the pollution discharge right trading. The total amount of water pollution control technology is combined with water pollution prevention and treatment technology to form a water quality management technology system, which includes three kinds of total amount control of water pollutants, which are based on environmental capacity (EC), environmental target (ET) and the industrial characters(IC) respectively [1]. Among them, the allocation of water pollution load is the core and difficult point in water pollution total amount control system [2]. 1.1. Basic principles of pollution load allocation: According to the researches and practices of pollutant total amount control in China, the basic allocation principles include five aspects: sustainability, equity, efficiency, technical feasibility and operability [3]. In market economy, to balance the rights of polluters‟ using of environmental resources and the obligation of pollution reduction, the principle of equity is the first principle to be followed [4]. And then according to the cost-effectiveness analysis of discharge enterprises, the contribution of water pollution by various sources and the financial capability of small business, pollution load allocation should use efficiency principle. In addition, implementing the load allocation plan should also take the technical feasibility and operability into consideration [2]. 1.2. The main allocation methods: Our load allocation methods, mostly based on the water environmental capacity or the environmental target, allocate water pollutant load using the economic optimal principles (the efficiency principle) or the principle of equity. There are some allocation methods based on the principle of equity, such as equal percent removal, the proportion of pollution contribution method [5], the AHP analysis method [6] and the Gini coefficient method [7]. In these methods, various factors are taken into account to reflect the development and the relationship of natural resources and human society. These methods are scientific and comprehensive, but lack the impact of pollution from different sizes of companies. What‟s more, the allocation methods based on the principle of efficiency include the minimal handling cost method [8], the maximum marginal benefit method [9] and a variety of mathematical programming models [10]. Under the conditions of total amount constraint, such methods reduce the pollution load to strive for maximizing enterprises‟ economic efficiency. But it is easy for the discharge companies to be assigned more reduction load which have high removal efficiency and effective management. In addition, allocation methods take both the principles of fairness and efficiency, such as the multi-index comprehensive planning method [11], AHP and the Gini coefficient feedback method [12]. These methods combine the advantages of the first two kinds of methods, but the large amount of calculation, taking many factors into consideration and low practical operability are the disadvantages make it can‟t be widely used. Actually, each load allocation method has its own suitable principles and characteristics. There are a series of objects for water pollutions load allocation, including water basin, the water function zoning, administrative units, sewage outlets and pollutant discharging points. Depending on the different 972 Yue ZhangY et Zhang al. / Procedia et al./ P Environmentalrocedia Environmental Sciences Sciences13 (2012) 8 943(2011 – )953 970–980 945 characteristics of distribution objects, the principles of allocation method are not same. So it is difficult to meet the interests of various level objects by one kind method of load allocation. 1.3. Research progress This paper intends to establish a multi-level load allocation method. In the regional level for the water function zoning and administrative units, the environmental Gini coefficient analysis method is applied to set up an appropriate optimal allocation model. The regional demand of water resources (economic, social status) and the supply of water resources (environmental capacity, water conditions) are taken into overall consideration. In the discharge unit level, optimal generation performance standard (GPS) method bases on the principle of efficiency is used to improve the generation performance and reduce pollutant load. Priority load allocation rights will be given to enterprises which have high utilization of environmental resource. And gradually establish the region's industrial structure which is appropriate with the water capacity. After design the basic allocation program, the system needs to be modified according to the unit's actual emission situation, the impact of different size and position of sewage points. This allocation program can combine the regional level and emission point level, according to the principles of fairness and efficiency. It makes the allocation results more acceptable by two levels. Wei Wang and Yuan Wang of Tianjin University make use of such method and have studied the total water pollutants load allocation in Tianjin. The results of the local load allocation appear effective and suitable to the actual pollution status. 2. Multi-level load allocation method 2.1. In the regional level, the Gini coefficient method Gini coefficient is proposed by Italian economist Gini, according to the Lorenz curve in the early 20th century, which is an indicator to determine the extent of equal for national income. Shown in Figure 1, the calculation of Gini coefficient uses trapezoidal