Herodion-Beit Fajjar Well Field of High Quality and Resource-Productivity Groundwater Endangered by Severe Over-Pumpage

Abstract

Herodion Beit-Fajjar well field is located in a syncline area about 8 km to the east of the Surif Anticline, the main anticlinal structure in the southern West Bank. The selected well field lies within 35degrees9' and 35degrees16' longitude 31degrees35' and 31degrees43' latitude which is referenced on the Palestinian Grid as being between 110-125 N and 165-175 E. The area enjoys a Mediterranean climate, hot, dry summers and mild, wet winters, with 600 mm as the average annual rainfall and 1400-1600 mm as the annual potential evaporation. The elevation of the well field ranges between 750 masl at the well of PWAII and 455 masl at well of Azzariya 3. The main geological outcrops in the area are Turonian-Cenomanian limestones, dolomite and marls of Jerusalem Formation and to less extent the Bethlehem Formation. The wells in the area are discharging two main regional aquifers, the Turonian Cenomanian (Upper) and the Albian (Lower) aquifers separated by the marls and clays of the Yatta Formation. Both the surface and ground water flow eastward directed by the topography and the dip of the geological formations respectively. Studies about the groundwater quality conducted between 1996-2002 show that the water of the wells is of calcium carbonate type and of high drinking water quality from both the biological and chemical point of view. The content of H-2 and O-18 represents the local precipitation, while the content of 3 H dates it back to the 1950's. However, measurements of the static water levels at the different wells in the field show that the well field is subject to severe over-pumpage, lowering the water table e.g. at well Herodion 3 by 85 m between 1981 and 1997 and about 37 meters at well Herodion 2. Thus, Herodion Beit Fajjar well field is an important source of groundwater, but subjected to heavy over-pumping. Therefore sustainable management actions must be taken to protect these precious water resources.