| Ecological environment is the basis for human survival and development,among which the degree of exploitation of soil and water resources is related to the stability of ecological environment and the sustainable development of human economy and society.Since the 1980 s,with the increasing economic scale and population in the middle reaches of the Heihe River and the speed of urbanization,the degree of regional exploitation of soil and water resources has also continued to increase.The basin has witnessed unreasonable allocation of water and soil resources utilization,tension between people and land,intensified contradiction between water resources supply and demand,and declining carrying capacity of water and soil resources.This has led to the continuous deterioration of the regional ecological environment,which will seriously affect the stable and sustainable development of the regional economy if it continues to develop.Based on the above-mentioned background,this paper integrates survey research,qualitative research and quantitative research,theoretical analysis and practical application by studying the existing studies on the development and utilization of water and soil resources in arid areas at home and abroad.The changes in the quantity and spatial pattern of land use in the middle reaches of the Heihe River,the changes in water use and water resources carrying capacity in the middle reaches,and the changes in water and soil resources matching and ecological landscape are comprehensively analyzed.And based on the results of the analysis of the changes in water and soil resources,the simulation prediction of land use pattern and water resources bearing and water consumption is carried out.The research results of both the current water and soil resource use changes and simulation prediction results are used as the starting point to provide ideas for the optimal allocation of water and soil resources in the future.The main conclusions are as follows:(1)By studying the total water consumption,water consumption of each type,water consumption structure and water resources carrying capacity in the middle reaches of the Heihe River,we analyzed the changing trend of water resources utilization.1)The total water consumption,agricultural,industrial and ecological water consumption all decreased by25.77%,21.38%,80.88% and 63.38% respectively,while the domestic water consumption was basically stable.2)The average water consumption structure of agriculture,industry,life and ecology is 89.73:2.20:0.14:2.43:5.64.3)The comprehensive rating value of water resources carrying capacity T is between 0.3 and 0.5,which is in a bearable state and the overall development is good.4)Under the influence of factors such as industrial structure adjustment and population change,the proportion of agricultural water consumption is too high,the water consumption structure is seriously unreasonable,and there is the phenomenon of agricultural water crowding out ecological water,which has a serious negative impact on regional ecological stability and ecological vegetation restoration work.(2)Quantitative and spatial change analysis of six periods of land use data from 1995-2020 in the middle reaches of the Heihe River was carried out by Arc GIS software.The results showed that: 1)Quantitatively,the increase rates of arable land and construction land area were32.97% and 46.72%,respectively,while the areas of unused land,forest land,grassland and water area decreased by 6.46%,40.4%,6.37% and 4.76%,respectively.2)In terms of spatial pattern,the transfer between land types is most frequent in the periods of 1995-2000 and 2015-2020,with most of the unused land and grassland being converted to cropland and construction land being mainly transferred from cropland.3)The degree of land development and utilization in the region is moderate to low,and in general it is in the stage of rapid development,the influence of human factors on the region is increasing,and the intensity of land utilization is gradually increasing.4)Affected by economic and social development and policies,the regional expansion of farming is serious,leading to an increase in the degree of damage to the ecological environment,coupled with the constraints of natural conditions such as arid climate and water shortage,the growth rate of ecological land such as forest and grass in the study area is slow,and ecological restoration is very difficult.(3)The changes of water and soil resources matching degree,land use degree,landscape pattern and vegetation ecological water demand in the middle reaches of the Black River were analyzed to explore the regional ecological change trends.The results show that 1)the Gini coefficient G in the middle reaches of the Black River is less than 0.2,the spatial distribution of water and soil resources is balanced,and the degree of matching is good.2)The dominance of dominant patches decreases,the outward trend of various landscapes strengthens,the aggregation between the same landscape types decreases,the richness,spatial heterogeneity and fragmentation of landscape types increase,and the overall landscape shows the development trend of diversification and homogenization.3)The average ecological water demand of vegetation is 317 million m~3,and the overall first falls and then rises,and the ecological water demand cannot be guaranteed.(4)The CA-Markov model was applied to simulate land use,and the gray residual Markov model was used to predict water consumption and water carrying capacity.The results show that: 1)the study area will continue to maintain the development trend of decreasing unused land area,increasing construction land,arable land,grassland and water area,expanding the scale of cities,slowing down the development of arable land,and better restoration of ecological land such as forest and grass.2)The water consumption in the study area continues to decrease,the carrying capacity of regional water resources continues to improve,and the water conservation policies and measures currently in place should continue to be maintained.3)In response to the deterioration of the ecological environment in the middle reaches of the Heihe River due to the unreasonable configuration of the development and utilization structure of water and soil resources,suggestions for ecological environmental protection such as strengthening the optimization of land use pattern,strengthening the comprehensive management of water resources,adjusting and optimizing the regional industrial structure and establishing an ecological and environmental monitoring and early warning mechanism are put forward. |
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