Using Remote Sensing and Geographic Information System (GIS) Techniques to Evaluate the Sand Reservation Project in Al Ahsa Oasis

Abstract

The problem of sand creeping on to agricultural land in the oasis of Al-Ahsa in the Eastern Province of Saudi Arabia is one of the most important manifestations of desertification. The agricultural land of the oasis has shrunk due to the northern, north-east and north-west winds that bear sand from the deserts of Dahna, Nafud and Jafora, which surround the oasis on the west, north and east. Due to the historical importance of the oasis for agricultural and residential use, the Sand Reservation Project has been established to stop the encroachment of sand onto the oasis and to address related environmental problems. The aim of this study is to evaluate the efforts to limit the sand creep onto agricultural lands in Al-Ahsa Oasis and to show to what extent the project has achieved its objectives in preserving agricultural lands in the region. A number of software programs such as QGIS 2.8.2, ERDAS Imagine 8.5 and IDRISI have been employed in all phases of the study to calibrate and classify Landsat images of different years (1979, 1987, 2000 and 2017, respectively). A digital elevation model (DEM) to study the relationship between the geomorphology of the area and its role in sand creep has been employed, and the Normalized Difference Sand Dunes Index (NDSI) and the Normalized Difference Vegetation Index (NDVI) have been applied. In addition to analysing the geomorphology and sand sediments for a variety of characteristics such as gradient and direction, surface runoff has been calculated, mapping and distribution performed, field measurements taken, direct observation of phenomena carried out, interviews conducted, and the DEM analysed. The results indicate an increase in the concentration of sand dunes in the northern parts of the study area and the deterioration of large numbers of fender trees, problems that require environmental assessment of the project and ongoing maintenance of areas still untouched by sand creep.