Estimating groundwater recharge using the chloride mass-balance method in the West Bank, Palestine

Abstract

The quantification of natural recharge rate is a prerequisite for efficient and sustainable groundwater resources management. Since groundwater is the only source of water supply in the West Bank, it is of utmost importance to estimate the rate of replenishment of the aquifers. The chloride mass-balance method was used to estimate recharge rates at different sites representing the three groundwater basins of the Mountain Aquifer in the West Bank. The recharge rate for the Eastern Basin was calculated as between 130.8 and 269.7 mm/year, with a total average replenishment volume of 290.3 106 m3 /year. For the Northeastern Basin, the calculated recharge rate ranged between 95.2 and 269.7 mm/year, with a total average recharge volume of 138.5 106 m3 /year. Finally, the recharge rate for the Western Basin was between 122.6 and 323.6 mm/year, with a total average recharge volume of 324.9 106 m3 /year. The data reveal a replenishment potential within the estimated replenishment volumes of previous studies for the same area. Also, the range was between 15 and 50% of total rainfall, which is still within the range of previous studies. The geological structure and the climate conditions of the western slope were clearly play an important role in the increment of total volume. In some cases, such as the geological formations in the Northeastern Basin, the interaction between Eocene and Senonian chalk formations result in minimum recharge rates