| Due to the combined effects of global change and human activities,the ecosystem of the basin has undergone significant changes,and the health of the ecosystem has been deteriorating day by day,which has attracted extensive attention from human society.The Qinghai Lake River basin lies in the northeast of the Tibetan Plateau,and its ecological health is of great significance to maintaining the ecological balance of the region and promoting human survival and development.With the disturbance of external pressure,the ecological and environmental problems of the river basin have become increasingly prominent,and problems such as climate change and human interference have seriously degraded the ecological health of the river basin.On this basis,the evaluation of the ecological health of the river basin is of great significance for understanding its ecological health and promoting the sustainable development of ecological health in the river basin.This research takes the Qinghai Lake basin as the research object,combined with RS and GIS,through acquiring remote sensing image data,meteorological data,landscape data and social statistical data,a PSR model including 14 evaluation indexes including population density,livestock density,annual precipitation,annual wind speed,SHDI,SHEI,ecological elasticity,NPP,ecological service value,Contag,fragmentation index,vegetation coverage,water body density and per capita GDP was constructed,the ecological health status of Qinghai Lake River basin in 2005,2010,2015 and 2019 was evaluated,and the characteristics of ecological health and its development trend in 2005-2019 were obtained.The main findings are as follows:(1)in 2005,the eco-health Index of Qinghai Lake River basin ranged from 0.317 to 0.656,with an average of 0.514,which was classified as health grade.The area of five grades of ill-health and very healthy is 55.04 km2,540.37 km2,5716.38 km2,16971.53 km2 and 1733.68 km2 respectively,and the total area of health-very healthy grade is 74.77%.The ecological health level of Haiyan County is relatively low,with the morbid-sub-health level being the main one,while the other three counties have relatively high ecological health level,and the overall ecological health condition is good,the function is relatively perfect,and the influence of external pressure is relatively small,some problems may exist in the ecological environment in some areas.(2)in 2010,the Ecological Health Index of the watershed was 0.349-0.655,and the average comprehensive index was 0.532,which was in the health grade.The area of eco-health grade region is mainly sub-health-very health,which is 7134.85km2,14342.25 km2 and 2744.36 km2,accounting for 96.82% of the total area.The sick-unhealthy grade area is 2.5 km2 and 793.04 km2 respectively.The spatial distribution of morbid-sub-health grades is concentrated in the northeastern of the basin,Haiyan County;while the very health grades are mainly distributed in the southeastern of the basin,Tianjun County;with the largest distribution area of health grades.In 2010,the organization structure of the Qinghai Lake River basin was stable,the ecological function was normal,the impact of external pressure could be well handled,and the ecological health condition was good as a whole.(3)in 2015,the Comprehensive Index of ecological health of the watershed ranged from 0.347 to 0.680,and the average comprehensive health index was 0.492,which was sub-health level.The area of morbid-sub-health grade was 13974.49 km2,accounting for 55.86%,and the area of healthy-very healthy was 11042.50 km2,accounting for 44.14%.Sick and unhealthy regions are mainly distributed in the northwest of Tianjun County,sub-health Regions are mainly distributed in Tianjun County and Haiyan County,and health regions are mainly located in Gangca County and Gonghe County.The healthy region is distributed in the southeast of the basin,Gonghe County,and the ecological environment quality in the southeast of the basin is better than that in the northwest.(4)in 2019,the range of comprehensive index of eco-health was 0.279-0.707,and the average health index was 0.476,of which sub-health Area was the largest,accounting for 12556.03 km2,accounting for 50.19%.Spatially,the morbid-unhealthy regions are distributed in the north and south of Haiyan County and the Gangca County North-Western Territory,and the sub-health Regions are mainly distributed in the Gangca County and Tianjun County.The health level region is located in the southeastern part of the Tianjun County and Gonghe County of the river basin;very healthy,mainly in Gonghe County.In 2019,the ecological health status of the whole basin deteriorated,among which the ecological health quality of Gangca County and Haiyan County was worse,the ecological health level of Tianjun County was in the middle and the ecological environment quality of Gonghe County was the best.(5)from 2005 to 2019,the Average Comprehensive Evaluation Index of Ecological Health in Qinghai Lake River basin was 0.514,0.532,0.492 and 0.476 respectively.The overall health level changed from health to sub-health,and the ecological health status showed a downward trend.From 2005 to 2010,the Ecological Health Index of the river basin increased slightly,and the ecological environment of the river basin improved to some extent.The ecological changes in Gangca County and Gonghe County are relatively stable,but the environmental quality in Gangcha County has declined.The ecological changes in Tianjun County and Haiyan County are complex,and the overall trend is decreasing. |
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