| The Middle Route of the South-to-north Water Transfer Project is a strategic cross-basin water transfer project to alleviate the severe water shortage in northern China.The potential impact on the regional environment and ecology of the project is very complex.It not only has a certain impact on the future water supply,water quality and dynamics of the water source basin,but also has a profound impact on the regional land use and ecological environment.The fundamental source of water pollution is not only the rivers,lakes and reservoirs themselves,but more importantly,the human life and production activities closely related to land use in the basin.In recent years,the types of land use/land cover in the core area of the Middle Route of the South-to-north Water Transfer Project have changed greatly.Unreasonable land use in the region has resulted in increased soil erosion,reduced vegetation water conservation functions,and degradation and destruction of the ecological environment.The ecological environment not only directly affects the ecological security of Danjiangkou reservoir area and its upper reaches,but more importantly,it concerns the water safety of tens of millions of people in north China.The state vigorously promotes the construction of land ecological civilization and promotes the protection of land resource quality has become the core demand for sustainable development,defining that the development goal of "intensive and efficient production space,moderate living space,and beautiful ecological space" is an important foundation for optimizing the rational allocation of land resources and the construction of ecological civilization.The transformation of regional land use corresponding to the change of land use form will inevitably cause changes in the regional economy,society and ecological environment.One of its important manifestations is the transformation of the dominant functions of land use,that is,the transformation between the three dominant functions of production,ecology,and life what have a profound impact on the structure,function and ecological process of the regional ecosystem.This study optimizes the definition of the core area in the Middle Route of the South-to-north Water Transfer Project,using the method of combining GIS and geostatistics,and according to the classification of the dominant land use functions of the "Sansheng" land use,and quantitatively analyzes the structural and spatial characteristics of the land use function transformation in the study area.The ecological environment response model and ecosystem service value are used to explore the ecological environment effect status and temporal and spatial distribution characteristics of the area.At the same time,the spatial measurement regression model reveals the main influencing factors of land use transformation in the study area,and the measurement results of the LMDI decomposition model and the water environment quality reveal the influencing factors that lead to changes in the ecological environment effect in the area.Finally,based on the results of the previous research,optimizing control strategies and suggestions are put forward,with a view to providing data and technical support for improving the ecological environment quality of the water source area,rational use of land resources,and sustainable social and economic development,as well as providing decision-making basis for relevant departments to carry out scientific management and policy regulation in the area,and to ensure the clear water transfer of a reservoir to the north.The main conclusions of the research are as follows:(1)Based on the relevant national work plan and combined with the actual situation,this paper optimized the definition of the core area of the Middle Route of the South-to-north Water Transfer Project with the township administrative unit.The land use types in the study area was divided into production land,ecological land and living land according to the different aspects that were satisfied human needs.According to the statistics,the study area was mainly ecological land,accounting for 72.70% of the total area,in which the forest land was mainly ecological land.The second was production land,accounting for 26.21% of the total area,mainly for agricultural production land,which was widely distributed in space,showing the characteristics of more distribution in the east and south and less distribution in the west.Living land space was relatively small,only 1.09%.(2)This paper analyzed the transformation characteristics of the functional structure of land use in the area through the transfer matrix model,and concluded that during 2010-2015,the largest transfer ratio of the study area was production land,mainly forest land ecological land and agricultural production land transferred to industrial and mining production land,and the largest transfer rate was residential land,mainly urban residential land and rural residential land were transferred to industrial and mining production land.Between 2015 and 2018,the largest proportion of land transferred was residential land,which was mainly caused by the transfer of agricultural production land to urban living land and rural living land,and the land with the largest transfer rate was residential land,which was mainly transferred to agricultural production land and woodland ecological land.Using the center of gravity transfer model,the Lorentz curve and the Gini coefficient to analyze the spatial transformation characteristics of land use functions,it was calculated that the center of gravity migration of production land has been relatively concentrated in the past eight years what was caused by the obvious correspondence between the migration trajectory of agricultural production land and soil type of benefiting to crop growth.The migration of ecological land gravity center was mainly due to the substantial increase of ecological land area caused by the formal water supply of Danjiangkou reservoir.The migration of the center of gravity of living land was mainly due to the rapid development and location advantages of Wudang Mountain Special Zone,which led to the increase of urban living land in corresponding areas.The Lorentz curve and Gini coefficient reflected the differences in the distribution of the towns in the study area,and it was concluded that the spatial distribution of ecological land was relatively uniform,the production land showed a trend of uniformity year by year,and the distribution of living land was relatively uneven.It also revealed the towns and villages with a higher degree of specialization in the "San Sheng" space.Finally,using the spatial econometric regression model,selecting natural driving factors,socio-economic factors and traffic location factors,a total of 12 indicators,revealing the influencing factors that lead to land use transformation in each year and analyze their causes,so as to provide a scientific basis for the rational distribution of industries in the water source area and the economical and intensive use of land in the future.Overall,the transformation of land use from 2010 to 2015 was mainly driven by regional development,convenient transportation and natural factors.The major land use transformation types had changed from 2015 to 2018 which caused by agricultural production land to forest ecological land of poor cultivation effect,expanding the scale of aquaculture,the demand for food production and industrial development have led to the gradual deterioration of the ecological environment.(3)Firstly,using the ecological environment quality index and the spatial variability characteristic model concluded that there was spatial autocorrelation in the ecological environment quality of the core area of the Middle Route of the South-to-North Water Transfer Project from 2010 to 2018 what was moderate spatial variability.The ecological environment quality index in the region generally presented the spatial distribution characteristics of "high in the west and low in the east,high in the south and low in the north",and were regional differences and the overall pattern changes little.From 2010 to 2015,the overall environmental quality of the study area deteriorated slightly,and the comprehensive index of ecological environmental quality decreased from 0.658 to 0.655,which was mainly manifested in the transition from middle-quality and higher-quality areas to lower-quality and higher-quality areas,and the high-quality zone was transferred to the middle-quality zone.From 2015 to 2018,the overall environmental quality of the study area has been significantly improved,and the comprehensive index of ecological environmental quality has increased from 0.655 to 0.664,which was mainly manifested in the transfer of low-quality areas to medium-quality areas and higher-quality areas,and the higher quality areas were transferred out due to the high quality areas.Second,from the perspective of the main types of land use that led to changes in the regional ecological environment,from 2010 to 2015,the ecological contribution rate of land use transformation in the study area has improved less than the worsening effect,mainly represented by the conversion of forest ecological land and pasture ecological land to industrial and mining land what showed that during this period,the study area vigorously developed the industrial and mining industries at the expense of forests and grasslands,which led to a decline in the ecological environment.From 2015 to 2018,the ecological environment quality of the study area has been significantly improved,and the impact of the improvement of the ecological contribution rate of land use transformation was greater than the impact of deterioration,which was mainly manifested in the mutual conversion of ecological land and production land,and the areas of converted ecological land were greater than that of converted production land areas what showed that during this period,the Danjiangkou Reservoir’s official water supply and the implementation of returning farmland to forests reduced the abuse of forests and grasslands in the study area,enhanced the awareness of water ecological environment protection in the core water source area,and provided a curb for the expansion of the deterioration of the ecological environment.In this paper,the monetary value of the ecosystem service system was used to characterize its ecological environment effects,and the ecosystem service value equivalent factor table of the core area of the Middle Route of the South-to-north Water Transfer Project was reconstructed.Using the ecosystem service value evaluation model,it was concluded that the ecosystem service value of the study area has shown an increasing trend in the past eight years from 2010 to 2018,indicating that the overall ecological environment has shown an improved state.There was a slight decrease in the first five years that the biggest change was in cultivated land,and the increase trend was obvious in the next three years that the biggest change was in waters.Over the past eight years,arable land and grassland have decreased,resulting in a loss of 863 million yuan in ecological value.However,the rapid increase in water area has brought an increase of 2.355 billion yuan to the study area,keeping the ecological environment in the study area was maintained in a stable and rising state.From the perspective of the spatial distribution of ecosystem service value,the ESV of Cangfang Town was the highest,followed by Longshan Town and Laocheng Town,and Shangsheng Street and Longcheng Street had the lowest ESV.The high-value areas of land-average ESV were concentrated in the northern,central-eastern and southern parts of the study area,and the low-value areas were concentrated in the central-north,western and eastern parts of the study area.The amount of ESV change was basically consistent with the law of land use transformation,mainly because the expansion of urban scale has led to the conversion of ecological land to living land,resulting in a decrease in the value of ecosystem services.(4)From the measurement results of the LMDI decomposition model and the quality of the water environment to reveal the influencing factors that led to the changes in the ecological environment effect of the study area,it was concluded that the increase in the level of economic development led to an increase in the ecological environment effect,and the greater energy consumption per unit of GDP led to a decrease in the ecological environment effect,indicating that the study areas have been harmoniously dealt with the improvement of the social and economic development level and ecological environment protection.However,attention should be paid to the emission of energy utilization efficiency,and the process of energy utilization needs to be improved to reduce the emission of pollutants.According to the results of the evaluation of the water environment quality in the area,there was a clear correspondence between the heavily polluted and heavily polluted areas of the water quality and the low-quality areas and low-quality areas of the ecological environment,namely,Junxian Town,Xianghua Town,Longcheng Town,Shangji Town,Madeng Town also had more serious water pollution and poor ecological environment quality,and its moderately polluted areas also coincided with areas with lower ecological environmental quality.It showed that by 2018,many land use types in the study areas have been converted to water areas,which has led to the expansion of water areas,and the water quality safety problems caused by them have become increasingly severe.Water pollution has become one of the main influencing factors leading to the deterioration of the ecological environment.Finally,based on the previous research results,the rational use of land and environmental protection measures in the core area of the Middle Route of the South-to-north Water Transfer Project were proposed in terms of land use control measures,optimizing the ecological economic development model of the water source area,and strengthening the construction of the water source area data processing and information transmission system what will ultimately realize the sustainable development of resources,environment,and social economy in the water source area. |
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