Groundwater Basin Summaries
Dead Sea Basin

Well CA3029, near the Dead Sea, shows construction characteristics for a typical well completed in geologic unit Q1. Water is obtained from sand and gravel between the depths of 21 and 71 m, with a water level about 23 m below land surface, supplying an average 1 L/s.

Groundwater is recharged by precipitation at an average volume of 57 MCM/yr, and generally flows toward the Dead Sea. Groundwater is the principal source of freshwater in the basin and is withdrawn primarily from the Amman–Wadi Sir aquifer system, consisting of limestone and chert of geologic unit Ks. Other aquifers in the basin have limited potential because of low recharge rates and deep water levels that result in large pumping heads. In the vicinity of the Dead Sea, alluvial deposits, gravel, and sand of geologic units Q1 and Q2 also are used as a source of water supply. Major springs in the basin include El Maghara and Ein Gedi.

Groundwater levels in the Dead Sea Basin have shown a long-term decline in response to pumpage as illustrated in well CD1214, completed in the Amman-Wadi Sir aquifer system. Since 1984, water levels in the well have declined about 15 m. Because recharge to the basin is about 57 MCM/yr and current groundwater pumpage is about 85 MCM/yr, there is a net deficit that results in water-level declines in wells. Well CD1001 shows variations in chloride and nitrate concentrations over time. A pronounced rise in con-centration during 1984-93 may be related to water-level declines that induced vertical movement of water in areas contaminated by agricultural prac-tices, waste disposal, or other human activities.

In the Amman–Wadi Sir aquifer system, water is of good to fair quality, with total dissolved solids concentrations between 300 and 1,000 mg/L. Concentrations generally are greater in the lower part of the aquifer system (750–1,250 mg/L) than in the upper part (500 mg/L). In localized areas, such as the lower reaches of the Wadi Mujib, concentrations are as high as 1,500 mg/L. Concentrations generally are lower in the vicinity of recharge mounds in the central part of the basin, and increase in an eastward direction where the aquifer becomes more confined.