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Lanzhou University (2021)

Evaluation of Ecological Environment Quality of the Oasis Plain in Hexi Corridor Based on Remote Sensing

郭昆明

Titre : Evaluation of Ecological Environment Quality of the Oasis Plain in Hexi Corridor Based on Remote Sensing

Auteur : 郭昆明

Grade : Master 2021

Université : Lanzhou University

Résumé
Oasis,a unique geographical ecological landscape,is the environmental foundation for maintaining human activities in arid areas,which carries the dual pressure of resource development and ecological environmental protection.The quality and stability of the ecological environment of oasis had a great impact on the development of arid regions.The Hexi Corridor lying on the east side of the desert area in northwestern China is a typical ecologically fragile area.The oasis area in the middle of the Hexi Corridor is the core area of the economic development of the Hexi Corridor,and it is also the most densely populated area in the Hexi Corridor.Under the influence of relevant policies and regulations,human production and lifestyle are constantly changing and acting on the oasis,thereby affecting the ecological environment quality of the oasis area and its temporal and spatial dynamics.Clarifying the change characteristics of the ecological environment quality in the Hexi Corridor Oasis Plain Area is of great significance to the construction and development of the regional ecological environment.Based on Landsat remote sensing images,this paper extracted six ecological indicators,namely,greenness(GDVI),wetness(Wet),desertification(DI),salinity(MSI),dryness(NDBSI)and heat(LST),constructed a comprehensive Multi-index remote sensing ecological index(MRSEI)model,and generated a time series data set of MRSEI every 5 years during 1986-2020.And the changes of ecological environment quality of the Hexi Corridor Oasis Plain Area during the past 35 years were evaluated by employing mathematical statistics method,difference method and trend analysis method.The conclusions were as follows :(1)The constructed MRSEI index could comprehensively reflect the quality of the ecological environment in the Hexi Corridor Oasis Plain Area,and different factors had different effects on the quality of the ecological environment.GDVI and Wet had a positive effect on the ecological environment of the Hexi Corridor Oasis Plain Area,while DI,MSI,NDBSI and LST had a negative effect.The trend changes were as follows : GDVI fluctuated up,Wet first increased and then decreased,DI and MSI decreased,NDBSI overall changed less,and LST increased.(2)The quality of the ecological environment in the Hexi Corridor Oasis Plain Area was poor,and the spatial differences were obvious.The ecological environment quality grade of the study area had the largest proportion of poor grades and the smallest proportion of very good grades,which presented a spatial distribution pattern of good in artificial oasis area and poor in oasis edge and desert transition zone.In terms of different basins,the quality of the ecological environment in the Heihe River Basin was the best,followed by the Shiyang River Basin,and the Shule River Basin was the worst.(3)The changes of the ecological environment quality in the Hexi Corridor Oasis Plain Area were relatively stable overall,and tended to improve.The areas with stable ecological environment quality change accounted for 65.03%,which was much larger than the areas with dramatic changes(11.15%).In terms of space,the Shule River Basin had the most dramatic changes,and the Heihe River Basin was the most stable.The results of the change pattern showed that the significantly improved,slightly improved,slightly degraded,significantly degraded,and stable areas of the eco-environmental quality in the Hexi Corridor Oasis Plain Area accounted for 15.35%,12.48%,7.41%,6.93%,and 57.83%,respectively,with stable and unchanging types being the main ones.The study on the sustainability of changes in the quality of the ecological environment showed that the sustainability of the ecological environment in the Hexi Corridor Oasis Plain Area was dominated by weak sustainability,25.77% of the study area is developing towards the improvement of ecological environment quality,and 16.41% of the study area is developing towards the degradation of the ecological environment quality.While the quality of the ecological environment had been improved,it was also facing huge ecological challenges.

Mots clés : Hexi Corridor Oasis Plain Area ;MRSEI;Ecological Environment Quality Evaluation ;Remote Sensing ;

Présentation (CNKI)

Page publiée le 17 novembre 2021