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Lanzhou University (2017)

The Research on Oasis Ecological Evolution of Shule River Basin


Titre : The Research on Oasis Ecological Evolution of Shule River Basin

Auteur : 齐敬辉;

Grade : Doctoral Dissertation 2017

Université : Lanzhou University

The research on remote sensing monitoring and driving mechanism of ecological evolution in arid and semi-arid areas has always been the key contents of globe change research.Shule River Basin,which located in the westernmost part of Hexi corridor,is the border area between Northwest China Arid and Semi-arid Area and Qinghai-Tibet Alpine and cold region.Low precipitation but high evaporation of Shule River Basin result in sparse vegetation and fragile eco-environment.All the factors make it a sensitive area responding to globe climate change.Meanwhile,this area has been a vital Commodity Grain Base of Gansu province.Since 1980s,more than 100 thousand ecological immigrations have moved here by Gansu Provincial Government,which leads to rapid expansion of cropland and agricultural irrigation water consumption,aggravated conflict between human society and natural ecosystem,as well as a series of ecological environment problems.Nevertheless,the studies on Shule River Basin are weaker compare to Shiyang River Basin and Heihe River Basin,which are belongs to Hexi corridor region.Therefore,it is critical to strengthen the research on ecological evolution of Shule River Basin.Given the facts above,we se-lect this basin as study region.Based on the product data from remote sensing image(such as Landsat,MODIS,SPOT,NOAA)and statistical information of natural and social economy-related,this article give an analysis on the spatio-temporal character-istics of LUCC and Vegetation index variation in Shule River Basin since 1980s.The driving mechanisms of ecological evolution are also discussed by quantitative and qualitative analysis from natural and humanistic aspects and main conclusions are as follows.From 1987 to 2015,in the middle and downstream of shule River Basin,the area of cropland,construction land and shrubland had a net increase,while high coverage grassland(HCG),medium coverage grassland(MCG),low coverage grassland(LCG),wetland and non-vegetation land all presented a net decrease.The rate of land-use and land-cover change(LUCC)in the period of 2000~2006 and 2006~2010 were relative higher,but the rate of LUCC in other periods were much lower.The change intensity of MCG and HCG are in the first place,the next are LCG,shrubland and wetland,Construction land and cropland are in the third place,non-vegetation land was the last one.The pattern of regional LUCC was generally stable,except for cropland loss,the gain/loss change of other land-use/land-cover types were always in an active state.The main sources of cropland expansion were HCG,MCG,LCG and shrubland,the main target that cropland transferred out was construction land.The main sources of LCG increase were MCG,HCG and wetland,the main target that LCG transferred out were MCG,HCG,shrubland,and cropland.The main sources of MCG increase and the main target that MCG transferred out were HCG,LCG and shrubland.The main sources of HCG increase and the main target that HCG transferred out were MCG,shrubland and wetland.The main sources of shrubland and wetland increase and the main target that shrubland and wetland transferred out were HCG,MCG and LCG.The main sources of non-vegetation land increase were LCG and wetland,the main target that non-vegetation land transferred out was LCG.The main source of con-struction land expansion was cropland.The areas that land use types had changed ac-counted for 38.18%of study region,more than 10%of which were moderate and high intensity conversion since 1987.As for spatial distribution,there were few changes in the old irrigated area within the oasis.

Mots clés : LUCC; vegetation index; intensity analysis method; oasis exploitation;

Présentation (CNKI)

Page publiée le 26 mai 2018