Comprehensive Evaluation Of Environmental Sensitivity In Arid Inland River Basins

It is an important part of the national ecological civilization construction strategy to identify the regions where ecological environmental problems and potential ecological environmental problems occur under the current natural background and human interference.In order to protect the ecological environment in arid and semi-arid areas,harmony between human and nature can be achieved.In this study,Shiyang River Basin,one of the most densely populated arid inland river basin in northwest China,with the highest water resources development and utilization,the most prominent water use contradiction,and the most serious ecological environment problem,was taken as the research area to discuss and study its environmental sensitivity and spatio-temporal evolution characteristics.When we studied the environmental sensitivity of the Shiyang River Basin,we referred to the evaluation criteria of the European Space Agency(ESA)and the environmental sensitivity assessment index system proposed by Chinese scholars,and combined the natural environmental characteristic and social economy of the Shiyang River Basin.We selected six sensitive indicators of biodiversity,climate environment,soil salinization,land desertification,geological disaster and human interference from the perspectives of soil environment,biological environment,climate environment and geological environment.Using remote sensing(RS)and geographic information system(GIS)technology,we introduced the fully-arranged polygon comprehensive index method to construct a comprehensive evaluation model of environmental sensitivity in the Shiyang River Basin.We Evaluated the environmental sensitivity of the Shiyang River Basin in 1987,1995,2006 and 2018,and use qualitative and quantitative methods such as circle analysis,grid coding analysis,zonal difference analysis and spatial autocorrelation analysis to reveal the environmental sensitivity and regional distribution differences of Shiyang River Basin.The final research results show that:(1)From the perspective of the time change of comprehensive environmental sensitivity,the comprehensive environmental sensitivity of Shiyang River Basin was generally high from 1987 to 2018,in which the areas of moderately sensitivity,severely sensitivity and extremely sensitivity accounted for more than 50%of the total area of the study area,and the areas of severely sensitivity and extremely sensitivity accounted for more than 40%of the total area of the basin.From the perspective of the variation trend of sensitivity,the overall environmental sensitivity of the Shiyang River Basin showed a trend of first increase and then decrease from 1987 to 2018.The proportion of the severely and extremely sensitive areas of the comprehensive environmental sensitivity of the study area was increased from 40.1%in 1987 to 42.46%in 2006,and then decreased to 41.6%in 2018.The proportion of insensitive and slightly sensitive areas in the basin decreased from 39.47%in 1987 to 39.46%in 2006,and then increased to 40.35%in 2018.This shows that the ecological environment management in the Shiyang River Basin had achieved significant effects in the past 30 years,especially after 2006,the environmental management effects were particularly significant.(2)From the perspective of the spatial distribution of comprehensive environmental sensitivity,the spatial distribution and environmental accumulation effects of environmental sensitivity in the Shiyang River Basin from 1987 to 2018 were significant.Among them,the regions with higher sensitivity in the Shiyang River Basin were mainly concentrated in the Badain Jaran Desert and the Tengger Desert in the lower reaches of the basin.In addition,the peripheral regions of the basin oasis were also scattered.The regions with lower sensitivity were mainly concentrated in the middle and upper reaches of the basin,including the Qilian Mountains in the upper reaches of the basin and the inner oasis region in the middle reaches.(3)From the perspective of the characteristics of the spatial variation of comprehensive environmental sensitivity,the spatial change of environmental sensitivity in the Shiyang River Basin generally showed a stable situation from 1987 to 2018,and some regions showed a trend of fluctuations.The regions with reduced fluctuations were mainly distributed in the eastern and peripheral areas of the middle and lower reaches of the basin.The regions with increased fluctuations are mainly distributed in the oasis region and the oasis peripheral region in the lower reaches of the basin.In terms of area ratio,the area where the sensitivity remains stable was 30359.82km~2,accounting for74.81%of the basin area;the area of the rising wave area was 4492.26km~2,which accounts for 12.20%of the area of the basin,and the area of the falling wave area was5,297.76km~2,Accounting for 12.99%of the area of the basin,it could be seen that the environmental sensitivity of the Shiyang River Basin had decreased,which proves that the overall ecological environment quality of the area was developing in a good direction.