Comparisons and improvements of eco-compensation standards for water resource protection in the Middle Route of the South-to-North Water Diversion Project

Reasonable eco-compensation standards are conducive to increasing the enthusiasm of residents in the water source area of the water diversion project for ecological environmental protection and maintenance and for improving the water quality security of the water receiving area. In this paper, a comparative analysis of calculation mechanisms, formulas, and results of 7 types of eco-compensation standard methods for the Middle Route Project of the South-to-North Water Diversion Project in China is conducted. The research shows that the calculated results for the 7 types of methods differ greatly and considers that the cost and ecological service value methods are appropriate. Using this as the basic method to consider introducing market value of water resources, internal income of water source area, and government ﬁ nancial support for method improvement, the results show that the improved methods can reduce the gap between the per capita income of the water source area and the reference area, increase the satisfaction of both the water receiving area and the water source area, and provide support for overall socioeconomic development.


INTRODUCTION
The Middle Route Project of the South-to-North Water Diversion Project in China, with a total length of 1,432 km, provides water for residents, industry and agriculture (Construction and Administration Bureau of South-to-North Water Diversion Middle Route Project ) to 19 large and medium-sized cities including Beijing, Tianjin and more than 100 counties (county-level cities), and is a major infrastructure project to alleviate the severe shortage of water resources in northern China (Ministry of Water 'ten small' companies, stopped more than 300 new projects, and the area of soil erosion controlled exceeded 2 × 10 4 km 2 during the period from 2011 to 2015. The water quality in the water source area is maintained at Class II as a whole Research on eco-compensation began at the end of the 20th century. The internationally accepted concept is PES (Payment for Ecosystem Services) or PEB (Payment for Ecological Benefit); these terms mean that beneficiaries pay fees to the ecological service provider. Pagiola et al. () believe that eco-compensation should be applied by a market mechanism so as to achieve effective allocation of resources. Landell-Mills et al. () considered eco-compensation as an economic stimulus with the main purpose of improving the efficiency of natural resource management.
The eco-compensation approach studied in this paper mainly refers to the compensation of the water source area's transfer of the right to use water sources by the water receiving area to protect the local ecological environment and the development losses of the water source area (Zeng  Table 1 shows that the calculation formula of the ecological service value method has three forms and the costing calculation formula has three forms. The parameters involved in each calculation method in Table 1 were analyzed to find the common and uncommon parameters of these methods, so as to analyze the reasons for the large differences in the calculation results of eco-compensation in the same study area, as shown in Table 2.
Statistical Yearbook, socio-economic development bulletin, and land survey results Opportunity cost and willingness-to-pay method Questionnaire and Statistical Yearbook 7 Wang () Ecosystem service function core algorithm Bimax-Ecological service value; Bimin-Cost; C ei -Indirect cost; C D -Direct cost; C o -Opportunity cost; C i -Protection of input costs; Ca-Amount of cost of agricultural ecological environment in water source area; E r -Ecological benefits of water demand area; EW-Water market value; E E -Internal benefit of water source area; E k -Willingness to pay adjustment factor; Gs-Total amount of water transferred by the project; G-Total water resources of the water source area; IN-Government financial subsidy; μ-Impacts of secondary and tertiary industries on development of the economy; P r -Water value; Q-Quantity of water diversion; Oc-Opportunity cost; PU, PR-the averages of the ten-year urban and rural populations in the supplier area; Pi-the possibility of the i th bid value; R O , R-the averages of the ten-year rural citizens disposable incomes per capita in the reference, and supplier area, respectively; R i -Water quality correction factor; U O , U-the averages of the ten-year urban citizen disposable income per capita in the reference and supplier area, respectively; Vis-Non-market part of the value of water ecosystem service value; Vi-the i th bid value of the respondents; V-Economic value of the ecological service function of water source; Wi-Water allocation factor.

Analysis of difference in calculation results
Before Considering that the calculation results and statistical data correspond to years that used 7 types of calculation methods, the per capita annual income of each literature study area was calculated and compared with the per capita income of the reference area in the corresponding year, as shown in Table 3. The formula for calculating per capita annual income after compensation in the water source area is shown in formula (1) and the formula for calculating per capita annual income is shown in formula (2).
In method number 1, the calculation results of eco-compensation include Xi'an city, Baoji City and Dazhou City, so this study only takes the ecological compensation data of water

Analysis of calculation method mechanisms
Ecosystem services refer to products and services provided by ecosystems that can directly or indirectly enhance  Each method has the following differences in its mechanisms: (1) The value of ecological services provided by the water resource area can be divided into market value and non-market value. The market value contributes to the development of the water source area. This part does not need compensation by the water receiving area.
The non-market value includes climate regulation and soil and water conservation (Zhu ); with these factors being severely damaged during the water diversion project, this is an important part that needs to be compensated by the water receiving area. However, what the water source area loses is not only the non-market value of the water body but also the high-quality water resources. Therefore, the cost of the water resources should be added to the calculation in method 1 (Zhu ). At the same time, when calculating the value of the water resources in the project, the corresponding water quality adjustment factor must be adjusted. If the water source area provides water quality which is inferior to class III, the water receiving area needs to deal with the water resource quality by itself. The cost of this activity is reflected in the water quality adjustment coefficient.
(2) Table 2 shows that the common parameters in the calculation formula of the cost method are direct cost and opportunity cost and the non-shared parameters involve more variables. In theory, the lowest cost to provide qualified water is the sum of the opportunity costs and direct costs and, therefore, the amount of eco-compensation to be provided must also be based on this standard but the amount of compensation for horizontal eco-compensation must be deducted from the fiscal longitudinal compensation funds (Zhang  environmental protection and maintenance are conducted in the water source area, these also bring certain internal benefits to the water source area and should be deducted from the costs. (3) Method 7 (Wang ) in Table 1  The per capita income is higher than the reference area value of 3,988 CNY but the error for each item in this method is too great. It does not consider the current development status of the water source area or the acceptance capacity and willingness of the water receiving area.

IMPROVEMENTS OF ACCOUNTING METHODS FOR ECO-COMPENSATION STANDARDS Calculation method
In this paper, the compensation mechanisms of the ecological service value and cost-benefit methods are clear and there is high availability of required data. Based on this method, the market value of water resources, internal income of the water source, and financial support factors are introduced to promote the rationalization of the mechanism and to improve the methods. The improved eco-compensation standard calculation formulas are  shown in Equations (3), (4) and (6).
H-market value of the water resources; G s -total amount of water diversion; P r -market price of water resources; W-water quality adjustment factor.

Analysis of calculation results
At   Table 3. This method is affected by the inconsistency of the calculation data and years in the research literature.
Therefore, the phenomenon of the same research area, the same research period and different eco-compensation amount appears in Table 4. This study did not analyze the accuracy of the method parameters, so it is suggested that the data accuracy should be further improved in the calculation of eco-compensation amount to ensure the use of reasonable parameters for the calculation of ecocompensation.
When compared with Table 3, the per capita difference in Table 4 greatly decreases the income gap relative to the reference area and thus indicates that the relative interests of the water source area and the water receiving area can be balanced and the two sides are more accepting. According to Figure 3, we can see, in addition to research method 5, the deviation of the eco-compensation income difference is lower than before the adjustment, which indicates that the adjusted calculation formula is feasible and practical. Table 4 shows that the amount of eco-compensation in the same research area as the water resource area is different in different years, which indicates that the ecocompensation standards are not fixed; it is necessary to dynamically adjust the compensation standards.

Eco-compensation implementation suggestion
In order to ensure eco-compensation can be implemented smoothly, this paper puts forward the following suggestions. (2) Establish a system of joint meetings. The establishment of a cross-regional, cross-department and cross-industry joint meeting system is conducive to actively handling various issues arising from eco-compensation, implementing eco-compensation, and ensuring the normal play of project benefits.
The implementation of eco-compensation cannot be carried out without the promotion of the government.
Therefore, the authors believe that the government should participate in eco-compensation as the main manager.

CONCLUSIONS
There are many studies on eco-compensation of water resources. As for the Middle Route of the South-to-North Water Diversion Project in China, there are many calculation methods for eco-compensation in the water resource area, and the calculation results in the same area differ greatly, which seriously hinders the effective implementation of eco-compensation. So, in this paper, through a comprehensive analysis of the similarities and differences in the calculation process, the results and mechanisms of the seven types of eco-compensation calculations for the water source area of the Middle Route Project of the South-to-North Water Diversion Project it was found that the calculation mechanism is more reasonable from the perspective of ecological service value and cost-benefit calculation, and the required data for this method is easy to obtain. Therefore, the calculation formula of ecological compensation was improved on the basis of this method. Through the mechanism analysis, it was found that the ecological service value provided by the water