BEDROCK FRACTURE ANALYSIS IN THE WESTERN DESERT OF EGYPT USING ORBITAL REMOTE SENSING DATA: IMPLICATION FOR GROUNDWATER RESOURCES OF THE KHARGA BASIN

Identifying new groundwater resources in Africa is important because the Nile recharge may decrease by the end of the century affecting water stability in the eleven countries that rely on this river as a water source. Further exacerbating the demand for water in Egypt in particular is a growing population that already lives on a small per capita amount of water. A systematic method of spatial analysis of brittle structures may allow us to identify the groundwater resources that can mitigate this issue. We report preliminary results from remote sensing analysis of optical (Landsat Operational Land Imager) and radar images (Radarsat-1) and digital elevation models (Shuttle Radar Topography Mission) on the fracture intensity and kinematics in the Kharga Basin and surrounding area in Egypt’s Western Desert, defined by Landsat scenes: path 176 and rows 142, 143, and 144. The Kharga is a 220 km long N-S trending basin with a maximum width of 40 km. It is bound on the north and east by a limestone plateau, and within a small portion of the basin lies the Kharga Oasis. Precambrian basement outcrops are exposed in the southern portion of the basin. The basin lies within the Nubian Sandstone Aquifer (NSA). The Jurassic through Eocene sandstones of the NSA are divided into two depositional facies but are considered a single hydrogeological unit because of the open groundwater system that they form. The majority of the groundwater is from the past five pluvial episodes of the late Pleistocene and Holocene. This study was undertaken to identify areas of potential groundwater resources in attempt to alleviate the need for surface water from the Nile. For this we performed digital image processing and spatial analysis using ENVI and ArcGIS software. Directional filters, high-pass filters, low-pass filters, pan-sharpening, and hill-shaded digital elevation models were all used to enhance the geomorphologically-defined brittle structures in the region. The major structural trends present were NNE/SSW and E/W. Analysis of the fracture intensity and kinematics led to the identification of regions of high density fracturing, which could serve as conduits for the upward migration of groundwater. The densest area of fractures was seen on the plain west of the oasis.