Groundwater potential mapping using remote sensing techniques and weights of evidence GIS model: a case study from Wadi Yalamlam basin, Makkah Province, Western Saudi Arabia

In the present study, remote sensing techniques, GIS models and field measurements are integrated to identify and map groundwater potential zones at Wadi Yalamlam (Sa'diyah) basin, Makkah Province, Western Saudi Arabia. The study area is located in the Arabian Shield heterogeneous basement terrain. It is characterized by insignificant primary porosity and permeability and is mainly covered by massive and altered gneissose granites, diorite, and gabbro and metamorphosed basalts. Lithology, rainfall, lineament density, drainage density, slope steepness and landuse/landcover are the main hydrogeological parameters defined to be related to the groundwater storage in the study area. They are prepared using the processed satellite data and integrated using weights of evidence and index overlay GIS models to generate groundwater potential zones map. Within the GIS model, those parameters are assigned values of 30, 20, 15, 15, 10 and 10, respectively, as score values. The resulting groundwater potential zone map for Wadi Yalamlam basin is categorized into three main classes (high, moderate and low groundwater potential zones) based on pixel values. The results of this study indicate that the lower parts of the Wadi Yalamlam basin is the most promising area for groundwater occurrences and contains both high and moderate potential zones. High groundwater potential zones are located to the north of the main dyke area around Abu Helal farm. They are characterized by loose wadi deposits, flat areas, gentle slope (ranges between 0 and 5 degrees), low drainage density (< 100 D/30 km(2)) and shallow water table (water table is 7 m from the ground surface). The present study proved: (1) the usefulness of the processed remote sensing satellite imageries for generating several indirect groundwater parameters; (2) the usefulness of weights of evidence and index overlay GIS models for the integration process and the production of groundwater potential zone map along the study area.