Hydro-Geology

Groundwater Basins

           The study area lies over 3 groundwater basins; these are:

1-The southern part of the Eastern Mountain Basin

2-The Dead Sea Basin located in the Jordanian part of the study area

3-The southern part of the Jordan Valley Floor Basin.

The Eastern Mountain Basin

           The 800 m thick Mountain aquifer is hyddrogeologically the main karstic aquifer in the areas West of the Dead Sea.   Three subaquifers are developed in this area:

1- A Shallow Turonian Aquifer feeding some springs such as Wadi-El-Qilt springs,

2- An Upper Cenomanian Aquifer which is penetrated by wells; and

3- A Lower Cenomanian-Albian Aquifer which is penetrated by wells.

           The Eastern Mountain Basin covers an area of about 3,080 km² and includes the eastern part of the Mountain Belt and the steep Western Escarpment of the Jordan Rift Valley.  Groundwater is recharged by precipitation at an average volume of 172 MCM/yr, and flows generally in a southeastward direction toward the Jordan Rift Valley and the Dead Sea.  Other estimates of the annual groundwater recharge of the entire Eastern Basin are 125 MCM/yr (WSSPS, 2000) and 135.9 MCM/yr (CH2MHILL, 2002). However, the current abstraction rate plus annual spring flow is 171.1 MCM/yr divided between the Palestinian (69.8 MCM/yr) and the Israelis (101.3 MCM/yr) (CH2MHILL, 2002).  

            The southern part of the Eastern Mountain Basin covers an area of about 1,652 km².  Natural recharge areas of the lower and upper Cenomanian aquifers in the study area were obtained from the Hebrew University of Jerusalem. The total replenishment areas of the upper, lower and Turonian aquifers are 617 km² , 69 km2 and 70 km², respectively. The recharge volumes were roughly estimated by overlaying the replenishment areas with average annual precipitation. The connection between replenishment (R) and precipitation (P) was based on previous studies conducted in the study area (Guttman, 2000). The connection between replenishment and precipitation is:

(1) for p<300 mm/yr: R = 0.15p
(2) for 650 mm/yr > p > 300 mm/yr: R = 0.534(p-216)
(3) for p > 650 mm/yr: R = 0.8(p-360)
 

            Accordingly, the estimated natural recharge in the Palestinian part of the study area was found to be 61, 16.2 and 9.5 MCM/yr for the upper, lower Cenomanian and turonian aquifers, respectively. The natural discharge from the Eastern Aquifer is through springs and by flow into deeper aquifers (2-3 MCM/yr) and into the Dead Sea (3-4 MCM/yr).  Three major springs discharge water into the Dead Sea, these are: Fescha, Kane (Ghwair) and Samar (Turba). Several other smaller freshwater springs exist in the study area such as Ein Al Sultan.  Guttman and Simon (1984) summarized discharge measurements along the Dead Sea. The discharges were approximately 34.2, 17.75 and 10 MCM/yr in Fescha, Ghwair and Turba Springs. Discharge measurements from the smaller springs are approximately 18.7 MCM/yr. 

            Overlay of the Lithology Map with the recharge areas map (Map 1) have shown that the recharge areas are primarily composed of limestone, chalk and Chert formations (Table 1).

Table 1. Lithology of the recharge areas.

LITHOLOGY	Area (Sq Km)
Limestone, marl, Dolostone; 171 m	337.6
Limestone, Dolostone, Marl, Chalk, Chert	147.2
Chalk, Chert; 164m	130.3
Limestone, dolostone, marl, chalk, Chert; 227 m	103.4
Dolostone; 160 m	68.4
Conglomerate Units, undif	7.1
Chert, chalk, phosphorite, limestone; 86 m	6.9
Aragonite varves, sandstone, gravel, conglomerate, mudstone, gypsum; 32 m	5.9
Limestone, marl, chalk, sandstone; 670 m	4.7
Gravel, sand, clay, loess	1.4

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Map 1.  Lithology of Recharge Areas

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The Dead Sea Groundwater Basin

          The Dead Sea Basin covers an area of about 1,525 km 2 and lies within three physiographic divisions— the Jordan Rift Valley, Jordan Highland and Plateau, and the escarpments of the Jordan Rift Valley. The Jordan Rift Valley is a pronounced geologic depression formed by downward movement of faults.  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.

The Southern part of the Jordan Valley Floor Basin

           The Jordan Valley Floor Basin is located in the floodplain of the Jordan River south of Lake Tiberias. The entire basin is contained in the Jordan Rift Valley, a pronounced geologic depression in which elevations range from 210 to 400 m below sea level. The basin is underlain by alluvial deposits of soil, sand, and gravel, marl, and clay that infill the rift valley to a thickness of at least 2,200 m.  Groundwater is recharged by precipitation at an average volume of 21 MCM/yr (EXACT, Overview of Middle East Water Resources).  The part of the Jordan Valley Floor Basin located in the study area extends 11 km north of the Dead Sea and has an average width of approximately 40 km.  The total area is therefore approximately 440 km² .  Precipitation in the southern part of the valley floor averages 170 mm/yr (Range 125 mm/yr - 240 mm/yr) whereas potential evaporation averages approximately 1,830 mm/yr.  Recharge of groundwater in the southern part of the Jordan Valley is therefore minimal.

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Groundwater Abstraction & Spring Discharges

            The Eastern Mountain Aquifer

            Table 2 shows the average yearly abstraction of water from wells.  Mekorot Company operates several wells in the Palestinian (9wells) and Israeli (6 wells) parts of the study area.  The West Bank Water Department, on the other hand, operates 7 wells in the study area.  The Palestinian Water Authority was operating 8 wells in 2003 and is developing a number of wells with a total estimated annual abstraction volume of 13.9 MCM.  The actual production of the 8 operational wells in the years 2002 and 2003 however was well below their estimated yield. Total abstraction from the Eastern Mountain aquifer was 46.72 MCM/yr without accounting for abstraction from Moan 1 well and from 53 low yield agricultural wells. Actual total abstraction from Eastern Basin might be around 50 MCM/yr. Map 2 shows the location of wells in the eastern mountain aquifer.

Table 2.  Average yearly abstraction from the water wells in the study area.

Water Authority	Average Yearly Abstraction (MCM/yr)
Mekorot Water Company*,***	23.88
West Bank Water Department	7.8
Palestinian Water Authority	3.69
New Wells Palestinian Water Authority (Operational in 2002)	1.98
New Wells Palestinian Water Authority (Implementation Phase)	13.87
Palestinian Municipal Wells	0.5
Agricultural Wells**	5.2
Brackish Wells***	32.5
Total Abstraction from Water Wells	79.22

                *No data is available for Moan 1 Well

                ** The number of Agricultural wells is approximately 95 wells.                  Yearly abstraction volume data is available for 42 of these wells.                  Some of the remaining 53 wells are still operational, these are                 shallow wells (50-100m) with low yields.

                *** 2.5 MCM/yr of High Quality water are abstracted in the Tamar                  administrative Region by the water Company Mekorot but an                  additional 10.2 MCM of Fresh water and 32.5 MCM of Brackish water                  are also abstracted from the Tamar region to the west of the Eastern                   Mountain Aquifer.  All other wells are located in the Palestinian                  Territory.

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Map2. Location of water wells in the study area.

           Water quality from groundwater wells is generally good but is deteriorating.  Elevated levels of abstraction from the aquifer increased water salinity and chloride concentration (See Figure 1 for an example on increase in chloride concentration).  In addition, nitrate levels are increasing indicating pollution from the open discharge of untreated domestic wastewater.


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Figure 1. Chloride concentration as observed in Herodion 3 well

           The most productive well fields in the study area are the Herodion well field, the Jericho Well Field and the Beni Neim well field.  Water abstraction in the Jericho and Herodion well fields started in the 70s.  The drilling and operation of more wells in the Herodion well field caused a significant decrease in the water table level as observed in the log head data of the wells in the area.  Figure 2 shows the drop in the water level in three wells.  Herodion 2 water level was dropping at an average of approximately 1.5 meters per year whereas Herodion 4 well was dropping at an average of 3 meters per year.    The case of Hebron 1 well is most striking.  The water level in Hebron 1 well dropped from 357 m to 315 m.  Figure 3 is a three dimensional representation of the drop in water level observed in the lower Cenomanian aquifer of the Herodion Well Field.  In figure 3, the blue layer is a three dimensional representation of the water table level of the lower Cenomanian Aquifer in the year 1980.  The Grey layer, on the other hand, is a three dimensional representation of the water table level in the year 1999.  The elevation values in the three dimensional representation are magnified by a value of five for a better visual representation.  The drop in the water level ranges between 3 and 80 meters with a spatial average of approximately 14 meters.

 

Figure 2. Drop in water level in the Herodion Well Field

  
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Figure 3. A three dimensional representation of the drop in water level observed in the lower Cenomanian aquifer of the Herodion Well Field.

          The drilling of new wells in the Herodion well field is most probably going to increase the rate of drop in the water table level.  In the year 1998, the abstracted volume of water from the Herodion Well Field was approximately 11 MCM.  The designed annual discharge of the new PWA wells (PWA-1, PWA-3, PWA -11 and Hindaza) drilled in the Herodion Well Field is 5.2 MCM/year (CH2MHILL) and the expected yield from the JWC-4, Azzariya 1 and Azzariya 2 drilled in proximity to existing wells in the Herodion Well field is approximately 5.4 MCM/yr (Scarpa, 2004).  This will bring up the total volume abstracted from the Herodion Well Field to approximately 21.6 MCM/yr.  The actual abstraction however is not expected to reach such high yields.  In the year 2002, the abstracted volume from the PWA-1, 3, 11 and Hindaza wells was only 3.44 MCM which is equivalent to 66% of the designed annual discharge and to 46% of the pump test rate (Scarpa, 2004).   As the current abstraction volumes exceed the aquifers sustainable yield, the designed annual discharge volume of the new PWA wells, Hebron 1 and Hebron 2 wells will be referred to herein as a non-usable resource on the long run. the drilling of new wells in the Herodion well field is most probably going to increase the rate of drop in the water table level.

          Waters from the Herodion Well Field and Beni-Neim well field are fresh whether they are tapped from the Upper or from the Lower Cenomanian Aquifers.  In the Jericho Well field, waters tapped from the Upper Cenomanian aquifer are fresh whereas waters tapped from the lower aquifer are Brackish with Cl concentrations above 1,000 mg/l.  All the wells tapping from the Upper Cenomanian aquifer pump fresh water suitable for drinking, only Jericho 1 and 2 have very high Chloride content and have to be mixed with waters from other wells before supply for drinking.  The wells Mizpe Jericho 3 and 5 and Jericho 2 and T-12 have been abandoned due to high salt concentrations.

           Several Springs discharge water from the Eastern Basin.  Historic discharges from springs were approximately 82 MCM/yr.  However, abstraction of water from wells has reduced water discharges from springs.  32 water springs are found in the study area, 27 of which discharge an average volume of 18.7 MCM/yr whereas the three springs of Fashkha, Ghwair and Turba discharged prior to development of groundwater wells approximately 50 MCM/yr. Of the 27 springs, the springs of Ein Qilt, Ein Fawwar and Ein Sultan are the largest.  Ein el Sultan is characterized by a very steady discharge of 180 l/s (Eq. 5.7 MCM/yr), the combined discharge of Ein-Qilt and Ein Fawwar averages 150 l/s with occasional peaks in the winter months up to 2,000 l/s.  The annual discharge of the three springs averages approximately 13 MCM/yr.  The remaining springs are smaller springs and are used exclusively for watering shepherd animals or for agricultural purposes.  Except for Fashkha, Ghwair and Turba springs, all other spring waters in the study area are fresh with a TDI content of 8-11 meq/l.

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           The Dead Sea Groundwater Basin

          The annual recharge of the Dead Sea Basin was estimated at 57 MCM/yr (EXACT Project).  Incomplete data exists as regards to the level of water abstraction from groundwater wells.  However, in the project's study area (See Map 3), 27 groundwater wells exist.  These are mostly concentrated south of the Dead Sea.  The total annual abstraction from the wells in the study area is approximately 5 MCM/yr (Source ECO Consult Office).  Over abstraction in the Dead Sea groundwater basin as in the Eastern Groundwater Basin is a problem.  The water level in several water wells dropped by more than 15 meters in the last 20 years.

           In the Eastern reaches of the aquifer 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 western part of the aquifer system (750–1,250 mg/L) than in the eastern 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. Water quality generally deteriorates in an eastward direction where the aquifer becomes more confined.

Map 3. The Dead Sea Project Study Area

83 springs with an average annual discharge of 39 MCM/yr are located in the Dead Sea Groundwater Basin.  Chloride concentrations range between 40-1900 mg/l.  Chloride concentrations generally increase in an eastward direction.

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