Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Research on Extraction of Desertification Information of Horqin Sandy Area Based on Feature Space

Auteur : 于钧

Grade : Master 2022

Université : Liaoning Technical University

Résumé
In the past hundred years,the global ecological environment has undergone drastic changes,such as vegetation degradation,water shortage,increasingly serious desertification and other issues,which pose a severe challenge to the living environment of human beings.Horqin sandy land is located in the semi-arid temperate continental monsoon climate zone,in the farming-pastoral ecotone.The change of the natural environment and the frequent activities of human beings have caused the ecological environment in this area to be very fragile,and the land desertification has developed rapidly,and has become one of the four existing sandy lands in China.Therefore,it is urgent to monitor desertification in Horqin sandy land for a long time in order to provide reliable theoretical support for adjusting land use structure and improving ecological environment in this area.Based on this,this study takes seven issues of Landsat satellite data,land use data and statistical yearbook data from 1990 to 2020 in Horqin area as data sources,and uses human-computer interaction method to monitor and analyze the dynamic changes of desertification in the study area in recent 30 years from 1900 to 2020 based on ENVI,Arc GIS,Matlab and other software platforms.The main contents and conclusions are as follows :（1）The traditional NDVI-Albedo feature space model has low precision in desertification information extraction in areas with less vegetation coverage and areas with excessive vegetation coverage due to the influence of soil background and over-saturation of vegetation index inversion.Based on the principle of NDVI-Albedo characteristic space model,this study introduced the soil-regulated vegetation index（MSAVI）,which is more sensitive to vegetation information,as one of the parameters of constructing characteristic space,analyzed the linear relationship among the indexes,and put forward MSAVI-Albedo characteristic space model.This model is compared with the traditional NDVI-Albedo feature space model and TGSI-Albedo feature space model in desertification information extraction.The experimental results show that compared with the traditional NDVI-Albedo feature space model,the extraction result of this model is more stable.Compared with TGSI-Albedo feature space model,this model has better and more accurate extraction results for light and moderate desertification land.It shows that the proposed model has better applicability and robustness to Horqin sandy land.（2）Using the proposed MSAVI-Albedo feature space model,land desertification information was extracted from six administrative regions of Horqin Left Wing Middle Banner,Kailu County,Kulun Banner,Naiman Banner,Horqin Left Wing Back Banner and Tongliao City.The thematic maps of land desertification distribution in Horqin area from 1990 to 2020were obtained,and the change trend of desertification land area at various levels was analyzed.The results show that from 1990 to 2020,the area of desertification land decreased by4288.86km 2,among which the area of light desertification decreased by 1608.57km 2 ;;Moderate desertification area decreased by 1395.3km 2 ;;The area of severe desertification decreased by1284.99km 2.Generally speaking,the desertification land in this region presents the development pattern of"expansion-rapid recovery-stability".（3）Based on statistical yearbook,meteorological data and other historical data,the influencing factors of land desertification process were quantitatively analyzed by using the grey correlation analysis method,and the influence ratio and degree of driving factors on various land desertification areas in Horqin area were calculated,and the leading factors affecting land desertification were found.The analysis shows that policy factors have great influence on the change of desertification land area,which indicates that the policy of"Three North Shelterbelt"implemented in the end of 20th century and the policies of"returning farmland to forest"and"returning farmland to grassland"implemented in the beginning of 21st century have significantly inhibited the development of desertification.In addition,climate,economy and other factors also play an indispensable role in the evolution of ecological environment.The paper has 22 pictures,20 tables,and 113 references

Mots clés : Desertification ;Horqin sandy land ;Feature space ;Dynamic change ;Driving force analysis ;

Présentation (CNKI)