Comprehensive Evaluation Of Irrigation And Water Conservancy Construction Benefits Based On Ecology

Irrigation and water conservancy is a water conservancy enterprise serving agricult ura l production.The construction situation and management effect of irrigation and water conservancy projects are directly related to water security,food security and ecological security in China,as well as the construction of beautiful villages,the increase of farmers’ income,targeted poverty al eviation and the modernization of agricultural and water conservancy.In recent years,the government attaches great importance to the construction of irrigation and water conservancy projects.The No.1 document of the central has repeatedly stressed the need to accelerate the construction of irrigation and water conservancy facilit ies,and the investment of irrigation and water conservancy construction grows steadily,but how is the actual effect of that?There has been some controversy.Under the background of water ecological civilization construction,it is of great significance to comprehensively and systematically evaluate the economic,social and ecological environmental benefits of irrigation and water conservancy construction from the ecological perspective,so as to improve the scientificity of decision-making in future irrigation and water conservancy projects,promote the increase of farmland grain yield,farmers’ income and the ecological environment protection of irrigated areas.Reading extensively relevant domestic and international research in this paper,and on the basis of systematical review,taking Hunan province as the research area,conducted a survey on the current situation of 7 typical large-scale irrigation areas and 14 key counties which were constructing small scale irrigation and water conservancy facilities.Analyzed and summarized the investment experience and main problems of irrigation and water conservancy construction in Hunan province in this paper,and established ecosystem services value(ESV)evaluation model of irrigation and water conservancy construction in 14 cities of Hunan province;Considering the spatial differences of natural environment,land use and agricult ura l functions(corresponding to ecosystem service values)in different cities,the ecological agriculture zoning plan of Hunan province was put forward.On this basis,the economic,social and ecological environmental benefits of irrigation and water conservancy construction in each ecological agricultural zone were analyzed and quantitatively calculated,and the actual comprehensive benefits evaluation model and risk evaluation model of irrigation and water conservancy construction in Hunan province were constructed.The main results are as follows :(1)The concept of ecosystem service value of irrigation and water conservancy construction was proposed.Supported by RS and GIS,a city-state scale evaluation model of ecosystem service value of irrigation and water conservancy construction was constructed based on the improved equivalent factor method.The ecosystem service values of irrigat io n and water conservancy construction in 14 cities of Hunan province in 2000,2005,2010 and 2015 were calculated.In the middle and late stage,the low ESV values were mainly concentrated in the central and northwest regions,while the high ESV values were concentrated in the eastern and northwestern regions,and most of the other regions were medium.The proportion of supply services,regulation services,support services and cultural services has been relatively stable over the years,with 3.5%,74.0%,18.3% and 4.2% respectively.(2)From the aspects of natural environmental conditions,agriculture functio n(correspond to ESV)and the land use situation to build index system of ecological agricult ure area of Hunan province(including 4 major categories and 13 minor categories),and Hunan province was divided into 7 ecological agricultural zones by using principal component analysis and system clustering method,which provided basis for space classification.(3)Studied the composition and quantitative evaluation method of irrigation and water conservancy construction benefits from three aspects of economy,society and ecological environment,so as to realize monetization of itemized benefits.Typical years,such as 2005(dry year),2014(quiet year),2015,and 2015(wet year),were selected to evaluate the benefits of Hunan province based on ecological agriculture zoning.The results showed that the law of comprehensive benefit is: wet year > normal year > dry year,which reflected the commonwea l,basic and external efficiency of irrigation and water conservancy projects.Among the 7 ecological agricultural zones,the main producing areas of grain,oil and aquatic products in Dongting Lake area(D2)had absolute advantages in benefits of yield increasing,water saving,farmland ecological breeding and soil quality improving,while the leisure tourism and cultural areas(A)in Changliu basin were in the lead in rural tourism benefits,which were consistent with the functional characteristics of each zone.The influence of irrigation and water conservancy construction on water environment was negative,the overall concentratio n exceeds the standard,and the control of farmland water environment pollution should be strengthened.(4)The comprehensive evaluation system and model of irrigation and water conservancy construction benefits in Hunan province were constructed by using AHP and entropy.Based on the ecological agriculture zoning,the comprehensive evaluation of irrigation and water conservancy construction benefits in Hunan province in 2015 was carried out.The economic benefits of the northern region were excel ent,the economic benefits of the central and southern regions were good,and the economic benefits of the southeast and northwest regions were relatively poor.From the northeast to the southwest,the social benefits were getting better and better,while in the southeast and northwest,the social benefits werw relatively poor.The ecological and environmental benefits in the north,south and southwest regions were mostly good or excellent,while those in the east central and northwest regions are relative ly poor.The overall comprehensive benefits of the central region were good,the comprehensive benefits of the south by the west were good,the comprehensive benefits of the north by the east were general,and the comprehensive benefits of the southeast and northwest regions were relatively poor.(5)Explored the risk factors of irrigation and water conservancy construction benefits,and established the index system and model of risk assessment of irrigation and water conservancy construction benefits in Hunan province based on fuzzy evaluation method.The risk distribution coefficients were determined by statistical method,and values at risk of irrigation and water conservancy construction benefits in each city of Hunan province were calculated and the risk map were drawn.The results showed that the overall risk of irrigat io n and water conservancy construction benefits in Hunan province was less.The benefit risk of irrigation and water conservancy construction in northeast and southwest China is relative ly less,while that in southeast and northwest regions was relatively large.