Study On Calculation Method Of Irrigation Total Cost Water Price Based On Ecosystem Service Value In Irrigation Districts

The low water price of operation and maintenance cost is not conducive to the sound operation of irrigation districts and the development of water-saving undertakings.And the high water price of full cost is difficult to implement.It leads to a increasingly prominent contradiction between the supply and demand of water resources in irrigation districts.It is necessary to give full play to the economic leverage of water price,rationally exploit water resources and speed up constructing a water-saving society in China.The key to giving full play to the leverage of water price is formulating a scientific and reasonable water price calculative method.The current water price system in China was studied,and a set of total-cost water price suitable for irrigation districts in China was established.The results show that:(1)It systematically summarized the composition,system and water price calculative method at home and abroad,and concluded two problems existing in the current total cost irrgation water price:one is the redundant investment in irrigation-engineering fixed assets;the other is that irrgation water price does not reflect irrigation-engineering construction external effects According to the two questions above,a basic calculative method of total cost irrigation water price based on ecosystem service value is proposed.(2)The concept of redundant investment in irrgation engineering was put forward.It considers that if irrigation engineering contains the following five situations:irrigation-engineering wasting facilities,irrigation-engineering idle facilities,irrigation-engineering constructing facilities with excessive standards,irrigation-engineering constructing facilities with excessive and large construction scale and engineering equipment for other purposes rather than serving irrigation,the above redundant investment should be deducted in calculating water-conservancy engineering replacement cost.In view of irrigation-engineering construction external benefits,the water price calculative system of agricultural water supply in irrigation districts incorporates the external benefits(3)It systematically studied ecosystem service value's assessment methods.It selected appropriate methods to evaluate irrigation-engineering external benefits in irrgation areas.Evaluating the flood-storage value in paddy fields should adopt the drainage cost method.The paddy field flood regulation and storage value is equal to the annual average drainage cost of additional drainage pumping stations in the absence of paddy field storage.Assessing paddy fields'partial climate regulation value should adopt the method of lowering the temperature and saving energy.The assessment should estimate the ecological service value of paddy fields' effect on lowering the temperature in hot seasons according to the amount of social electricity savings(4)This paper carried out empirical researches of water price in Yibei Irrigation District of Xinyi City.According to the current method of accounting water price,the total cost water price in irrigation districts should be 0.224 yuan/m3,and the water price of operation and maintenance cost should be 0.085 yuan/m3.If the proposed accounting method is used,the total cost water price of single agricultural water supply in irrigation districts is 0.175 yuan/m3,which is obviously lower than the total cost water price calculated by the traditional method.The revised total cost water price for irrgation excludes water-users' unreasonable burden and also considers irrigation engineering external benefits.The price formation mechanism is more reasonable and feasible.It can be used as a reference for accounting agricultural water price in irrigation districts in China.