A WEB-BASED GIS VEHICLE FOR THE ASSESSMENT OF GROUNDWATER POTENTIAL IN ARID LANDS: CASE STUDIES FROM EASTERN DESERT OF EGYPT AND THE SINAI PENINSULA

Increasing populations in arid and semi-arid countries world-wide are placing strains on the limited fresh water supplies in these areas. Such increasing demands can be addressed by: 1) identifying alternative renewable water resources in these areas, and 2) quantitative assessment of modern recharge. We have applied cost-effective integrated methodologies to achieve these two tasks taking advantage of recent advances in web-based GIS technologies and using as our test site the Eastern Desert of Egypt and the Sinai Peninsula. Specifically, a web-based GIS was first developed for the study areas and used to identify potential renewable groundwater resources in the Eastern Desert and the Sinai Peninsula. The Egyptian web-based GIS [URL: http://ims.esrs.wmich.edu/website/EG] encompasses datasets for geophysics (e.g., VLF, VES), remote sensing (e.g., Landsat TM, ASTER, TRMM), topography (e.g., SRTM), geology (e.g., geologic maps), hydrology (e.g., well locations, hydrogeologic maps, stream network distribution), and geochemistry (e.g., anions, cations, O and H stable isotope composition). Spatial analysis of the integrated data sets including the locations of successful wells has enabled the following: 1) identification of four reservoir types in the study area, and 2) selection of criteria for locating potential well locations of each of the reservoir types. Identified reservoir types include: 1) ascending deep Nubian Aquifer groundwater residing in shallow alluvial aquifers, 2) meteoric groundwater in fractured basement reservoirs, 3) alluvial aquifers recharged by modern meteoric precipitation, and 4) meteoric groundwater intercepted by dyke swarms crosscutting alluvial reservoirs. Site specific data assembled in a GIS database were used in SWAT (Soil Water Assessment Tool) to provide a continuous simulation of the overland flow, channel flow, transmission losses, evaporation on bare soils and evapotranspiration on vegetated canopy, and potential recharge. Results indicate that the shallow alluvial aquifers in Sinai and the Eastern Desert are receiving an average annual recharge of 463 x 10⁶ and 171 x 10⁶ m³/yr respectively, whereas the largely fossil deep Nubian aquifers in Sinai are receiving modern recharge amounting to 3.2 x 10⁵ m³/yr.