Assessment of Groundwater Vulnerability in Azraq Catchment in Fuhais-Jordan Using DRASTIC Model

Abstract

Groundwater resources in Jordan are under huge stresses. Accomplishing good water quality requires monitoring of water resources. Azraq spring considered the main source for drinking water of Fuhais City in Balqa governorate. The catchment area of the spring is less than 23 km2 and forms part of the side wadis feeding the groundwater basin in wadi Shuaib. This study aims to assess the vulnerability of groundwater to pollution that may result from agricultural activities and Fuhais wastewater treatment plant using GIS and DRASTIC model functions. Each symbol of the DRASTIC refers to one of the seven DRASTIC model parameters: Depth to water (D), Net recharge (R), Aquifer formation (A), Soil (S), Topography or slope (T), Impact of vadose zone (I) and Hydraulic conductivity (C). The final map of vulnerability showed 5 classes with different percent for each. These were: very low (5%), low (16%), moderate (11%), high (34%) and very high (34%). In terms of area, the high and very high vulnerability classes distributed over 7.75 Km2, while the low vulnerability distributed over 1.10 Km2. Implementation of DRASTIC model showed increasing the vulnerability of ground water to contamination in the western part of study area because of the vadose zone and due to soil properties in this part of the study area. As such, vulnerability to pollution increased from the upstream area, where the treatment plant is located to the downstream area following the direction of flow and according to permeability. Water depth, net-recharge and media of aquifer had neglected effect of vulnerability map because it had one value at overall study area for each one. DRASTIC parameters could be arranged according to its effect on vulnerability map as I > S > C > T > (D = R = A).