General Characterization of Groundwater Aquifer in Al-Faria Catchment by Using a Tracer-based Methodology

Groundwater is the most dependable water resource in Palestine. Characterising groundwater is the primary tool towards its integrated management. Al-Faria catchment is considered an indispensable groundwater resource in the north-eastern part of the West Bank, Palestine, since it supplies domestic inhabitants, their livestock, and the agricultural lands with needed amounts of water. The quality of groundwater in the catchment is affected by the untreated wastewater disposal and the runoff from the adjacent agricultural lands. This research aims at gaining a better understanding of groundwater hydraulic properties in Al-Faria catchment. It paves the way for further future research which aims to study the interaction between surface water and groundwater. A single-well injection withdrawal tracer test using Uranine tracer was applied to determine the seepage velocity and the effective porosity of the unconfined Neogene sub-aquifer. Data were obtained by conducting two tracer experiment tests during the wet and the dry seasons of 2012/2013. Breakthrough curves that show the recovered tracer concentration over time were constructed for each experiment. The main difference between the two tracer-based conducted tests on the selected wells was the existence of non-uniform pumping rates from nearby wells. The breakthrough curve for the wet season showed a progressive recovery of tracer with the highest peak reached after 54 minutes of pumping. The breakthrough curve for the dry season showed three and almost equal successive peaks at the 18th, 26th, and 36th minutes of pumping. Results showed high values of seepage velocity in the tested sub-aquifer. The calculated seepage velocity and the effective porosity of the tested well in the wet season were 9.2 meter/day and 4.3% respectively. The test in the dry season gave no clear results for the tested properties. The effect of the non-uniform pumping rates from the nearby wells of the tested well in the dry season caused the tracer to disperse into different directions with different gradients. The applied test was more efficient when conducted in the wet season; this result can be attributed to the intensive pumping of the many adjacent wells in the catchment which cannot be easily controlled. Finally, this research served as a preliminary work which paves the way for further groundwater tracer tests in the catchment; it should be stated that there is no previous experience in using the technique of single well injection withdrawal in this catchment.