Tension over equitable allocation of water : estimating renewable groundwater resources beneath the West Bank and Israel

Competition for water resources between Palestine and Israel is an ongoing cause of tension. The Western Aquifer Basin forms a major part of the complex, largely karst, limestone system of the West Bank Mountain Aquifer. The aquifer crops out and is recharged solely in the semi-arid uplands of the West Bank and groundwater flows west beneath Israel to discharge at the Yarqon and Nahal Taninim springs near the Mediterranean coast. Annual recharge to the aquifer is not easy to quantify but lies within the range 270×106 to 455×106 m3 a−1, and current uncertainties do not support definition of a single value of long-term average recharge. The resource is heavily exploited and abstraction is directly controlled and apportioned between Israel and the West Bank by Israel. The key to equitable apportionment is the determination of the long-term average recharge to the basin, which also requires definition of the eastern boundary of the basin to confirm the recharge area. Calculations include empirical formulae and process-based models that are likely to constrain the best estimate provided that there is appropriate, ongoing monitoring. Improved understanding can then be fed back into the model.