GIS and Remote Sensing

Biography

Biography: Munkhnasan Lamchin

Abstract

Desertification is a serious ecological, environmental, and socio-economic threat to the world, and there is a pressing need to develop a reasonable and reproducible method to assess it at different scales.The Hugnu Khaan region lies in the semiarid regions of center, Mongolia. Remote sensing and GIS are being used to study desertification in this region. In this paper, we used Landsat TM and ETM data between July and September first week in 1990, 2002, and 2011 to analyze the spatial and temporal patterns of the desertification using three indices: the Normalized Difference Vegetation index (NDVI), Topsoil Grain Size index (TGSI), the Land Surface albedo. We normalized the indicators, determined their weights, and defined five grades of desertification: non, low, medium, high, and severe. The times of image acquisition on the assessment indicators, sets of assessing rules were built, and a Decision Tree approaches were used to assess the desertification and we computed Compound Topographic index (CTI), Land Surface Temperature (LST) and Perpendicular Drought index (PDI). Then tested the correlation between the level of desertification and the six variables and compared with each other, checked by field data. We found that desertification in the Hugnu Khaan covered severe desertification more than 15 % of the total land area, the total area of severely desertified land was 7% in 1990. The desertification of the study area is increasing each year; in the desertification map for 1990–2002, there is a decrease in areas of non and low desertification, and an increase in areas of high and severe desertification. From 2002 to 2011, areas of non desertification increased significantly, with areas of severe desertification also exhibiting increase, while areas of medium and high desertification demonstrated little change.