STUDY AND ANALYSIS OF DESERTIFICATION PHENOMENON IN KARBALA GOVERNORATE BY REMOTE SENSING DATA AND GIS

Abstract

One of the most important issues facing Iraq is the threat of continued desertification resulting from climatic factors and human activities. Geographic Information System and satellites imageries play major role in developing a global and local operational capability for monitoring desertification in dry lands.This study intends to prove the capability of Remote Sensing data and Geographic Information System to monitor and study the desertification phenomenon. Part of Karbala Governorate, with an area of 768 Km2 is selected as study area.Four cloud free Landsat MSS, TM, ETM+, and SPOT5 scenes covering the study area were selected for analysis. Images were acquired for years 1976, 1990, 2001 and 2011. A site area was selected from the whole study area to investigate the possibilities of image classification and extract the indices images for the MSS, TM, ETM, and SPOT respectively. Normalized Difference Vegetation Index (NDVI) was used to create a map and extract the vegetation cover in the study area. Normalized Difference Water Index (NDWI) was used to create a map and define water bodies in the study area. Eolin Mapping Index (EMI) was used to map the areas which are subjected to wind erosion hazard. In order to identify the changes which took place during the four periods, three methods are used. Firstly; direct detection of change in indices images between different years is analyzed using visual interpretation in addition to statistical analysis. Secondly, differencing change detection analysis is applied to determine and to analyze the land cover changes over the four periods. Thirdly, the supervised classification is used to classify the images and to analyze the land cover changes during the four periods.The analysis shows that the study area suffers from severe desertification because it has suffered from erosion by wind and sand dunes, urban expansion, and lack of water resources especially in its western parts. The analysis also shows that the desertification decreased in the period between 1976 to 2001, and increased in the period 2001 to 2011 due to the increase in sand dunes to about 8.78 Km2. year–1, the appearance of water logged area problem that increased to about 0.65 Km2. year–1, the increase in urban area to about 0.38 Km2. year–1, in addition to geological factors, and the effect of bad climatic conditions.