The water of the thermal mineralized springs issuing between Afra in the south and the NE edge of the Dead Sea in the north (Suweima and Rama areas) originates from recharge in Aqaba Mountains and Disi areas. Here, the deep clastic sandstone system of Precambrian, Cambrian, Ordovician Silurian and Lower Cretaceous ages builds the geologic column and form one vertically and horizontally interconnected aquifer (Table 2), in which the groundwater flows in N-NE direction. The area north of Ras en Naqab Escarpment is covered by Upper Cretaceous calcareous rocks and receives direct recharge, where parts of the groundwater in these calcareous rocks containing residues of evaporates percolate down into the deep sandstone aquifer increasing the latter salt contents and temperature due to higher burial depth (Table 3). These increases occur gradually along the groundwater flow direction towards northeast. As can be seen from Table 1 the salinity increases from around 500 µS/cm in Afra springs to in Weida’a 620 µS/cm and to 850 µS/cm in Wadi Ibn Hammad and to 1200 µS/cm in Mujib-Zara area.

North of Mujib-Zara area, Late Permian and Triassic rocks containing evaporate residues intercalate between the Silurian-Ordovician and older sandstones and the Lower Cretaceous sandstones herewith adding to the deep sandstone aquifer system new geologic formations. The groundwater percolating through the Late Permian-Triassic rocks dissolve the evaporates and causes increases in the water discharged from the deep sandstone aquifer system in the area of Zarqa Ma’in and north of it to the north eastern edge of the Dead Sea.

The thermal water temperature increases or decreases according to the mixing ratios of water percolating down from the Upper Cretaceous aquifers, the percolated depth of the groundwater, and the contact with the atmospheric air in the discharge area.

The discharge temperature (Table 1) changes from 45˚C in Afra to 32˚C in Weda’a, to 45˚C in Wadi Ibn Hammad, to 56.5˚C in Zarqa Ma’in Shallala spring, and to 35˚ in Suweima. SiO₂ geo-thermometry gives reservoir temperatures of 75˚C - 82˚C (Sawarieh, 2000; Rimawi & Salameh, 1988; Vlastimil, 1988; Salameh, 1986; Salameh & Khudeir, 1983; Truesdell, 1978).

The pH of the water ranges from 6.12 to 7.12, although all these waters contain H₂S and CO₃ gases, which lower the pH values to below 6.00, but spring water contact with the atmospheric air accompanied with the release of H₂S and CO₂ gases before discharge seems to be responsible for the increased pH values.

The salinity of the water increases systematically from south to north, because of the gradual addition of down percolating Upper Cretaceous calcareous aquifer water containing residues of evaporates into the deep sandstone aquifer system, which possesses originally low salinity of about 500 µS/cm. This increase reflects the systematic gradual increase in the concentrations of the salinity parameters of Ca, Mg, Na, K, Cl, and SO₄ from south to north.

The other contribution to the composition of the thermal waters originates from dissolution of evaporates and carbonates from the, in the area to the north of Mujib River, intercalated Late Permian/Triassic rocks and the release of these salts into the sandstone aquifer system hosting the thermal mineralized water.

Bromide concentration shows strong increases from south to north from 30 µg/l in Afra to around 6000 µg/l in areas receiving Late Permian-Triassic water in Zarqa Ma’in and to the north of it.

The concentrations of the other components such as HCO₃, Fe, Mn, Pb, CO₃ and radon depend on the contact of the aquifer water with the atmospheric air in their discharge sites resulting in volatilization, dissociation, disintegration or precipitation of these components.

In the area extending from Suweima at the NE edge of the Dead Sea to Zarqa River in the north (Deir Alla) many thermal mineralized springs and seepages used to discharge along the eastern side wadis of the Jordan Valley. In Deir Alla at the entrance of Zarqa River into the Jordan Valley the thermal mineralized springs which used to issue from the Triassic and Jurassic rock series had before over-pumping started been used in therapeutic purposes. Also in Suweima area several springs and seepages used to discharge thermal mineralized water. That thermal mineralized water was encountered in boreholes sunk into the Triassic-Jurassic formations such as JICA wells 1-6 (JICA, 1995). The composition of this water is listed in Table 1 on the examples of Suweima (JICA well 5), Rama and Deir Alla springs. These water sources show somehow similar composition and their temperature ranges from 31˚C - 35˚C with different dissolved amounts of sulfates and halite.

The main source of their composition originates from the water rock interactions and reduction processes with the Jurassic and Triassic rocks containing residues of evaporates and organic matter.

In the area north of Zarqa River the thermal mineralized water issues from the upper most calcareous rock sequence of the Upper Cretaceous rock series composed of limestone, chert and phosphates which in this area are confined by a thick sequence of Uppermost Cretaceous-Tertiary bituminous marls (Table 4).

The salinity o the thermal mineralized water in this area is relatively low 980 - 1336 µS/cm. The temperature of the discharged water ranges from 36.1˚C to 52.7˚C. SiO₂ geothermal measurements give reservoir temperatures of 60˚C - 65˚C. The curative properties of the water in this area are related to its temperature, H₂S, radon and CO₂ contents and to the mineral assembly and ionic ratios.

The aquifer containing the thermal mineralized water is recharged along its outcrops in the Ajlun Mountains and the highlands at a distance of 20 - 25 km southeast and east of the discharge areas.

The water constituents originate from water-rock interaction of the infiltrating rainwater with the matrix of calcareous rock aquifer. However, in areas where the aquifer becomes confined by the overlying Bituminous Marl Formation reducing conditions prevail, producing H₂S, CO₂, and NH₄ gases lowering herewith the pH value of the groundwater which results in the dissolution of some trace elements including uranium disintegration series daughters such as radium, which, within that series, disintegrates into radon gas.

The curative properties of the water in this area are related to temperature, H₂S, radon and CO₂ contents and to the combination of cations and anions.

The drop in the Dead Sea level, which has been taking place since about 5 decades due to the development and use of its feeding waters, reached now around 37 m. Among the consequences of such a drop, the groundwater bodies in the surrounding areas of the Dead Sea, connected with the Dead Sea water via the interface started to readjust hydro-dynamically to reach at a new equilibrium state (Salameh & El-Naser, 1999, 2000a, 2000b, 2005, 2008). This readjustment is achieved when the groundwater levels drop by the same rate of the sea level. In areas close to the shore (10 s of ms) the readjustment takes place in short periods of time, days or weeks. But, in areas at distances of hundreds to thousands of meters the readjustment takes longer times depending on the hydraulic conductivity of the involved rocks. Nonetheless, such readjustment expressed in dropping groundwater levels is imperative (Figure 3).

Many of the thermal mineralized springs, especially those discharging along the eastern escarpment of the Dead Sea are vulnerable to the drop in the Dead Sea level such as, Zara, Zarqa Ma’in and Suweima (Figure 4). Therefore, the dropping Dead Sea water level is threatening the discharge of the springs’ water and their continuity. Decreasing and ceasing of spring discharges in Zara and Suweima area can be easily seen in these areas close to the Dead Sea (Figure 4).

In the groundwater up-gradient areas of Zarqa Ma’in, Himma, North Shuna, Deir Alla, and Abu Thableh thermal water sites, wells were and are planned to be

drilled to extract the groundwater for all use purposes. Because these wells tap the same groundwater bodies feeding the thermal springs, the discharge of these thermal springs started decreasing and with the passage of time, the springs will eventually cease. In Himma area (Figure 5), some thermal springs have already dried out and others are threatened to dry out in coming years as a result of drilling Mukheiba and Wadi El-Arab wells (Figure 6).

The thermal deep well of Azraq with spa facilities used to produce artesian thermal mineral water, but due to artificial groundwater extractions from the surrounding area, the discharge of the artesian well decreased gradually and stopped with declining piezometric level. This has led to the closer of the spa, which was in operation for about 30 years.

Also along Zarqa River, at around 300 meters east of Jarash Bridge a thermal mineralized spring called El-Hammam used to issue and feed Zarqa River. As witnessed by the ruins around, it has been used as spa since thousands of years.

During the last two decades, because of well drilling and groundwater extractions from the same aquifer, the spring dried out and the spa site abandoned.

Drilling of wells in Deir Alla (Abu Zighan) at the entrance of Zarqa River into the Jordan Valley had led to total dryness of the nearby Deir Alla thermal springs. The heavy extractions of groundwater from the Jurassic and Triassic aquifer containing evaporates led to accelerating dissolution of gypsum and halite which with time resulted in the formation of underground cavities which widened into caves. The ceilings of such caves collapsed and formed sink holes at ground surface (Figure 7).

In the course of exploring the deep groundwater along the eastern foothills of the Jordan Valley area a series of deep wells were drilled in the 1980s which encountered brackish artesian water from the Jurassic-Triassic aquifer, and in some places mixed with Kurnub (Lower Cretaceous) aquifer water. North Shuna and other wells to its south of it were drilled into the Upper Cretaceous confined aquifer.

The problem started when the drilling companies were not able to stop the artesian flow of these thermal mineralized water wells. Neither has the water been used for any purpose except the limited use of parts of North Shuna well water in a spa, nor has the discharge of these wells been stopped to conserve the groundwater resources. Moreover, the discharged brackish water from the flowing wells found its way to perennial fresh watercourses causing their original water to deteriorate and the environmental conditions to degrade. Such wells were drilled in Wadis: Hisban, Kafrain, Rama, and North Shuna. Other wells were drilled in Abu Zighan area, east of Deir Alla, which caused the ceasing of discharge of Deir Alla thermal mineralized springs used as a spa.

These artesian wells’ water originate from aquifers extending eastward under Jordan. Their water supports all overlying aquifers’ groundwater and forms the backbone of all the overlying fresh water aquifers, which produce water for drinking purposes.

The release of the artesian water from the deep aquifer is causing declines in the groundwater levels and the seizure of thermal water springs. It is an emptying process of a groundwater body without any proper use of the extracted water. In addition, some water from the overlying fresh water aquifers will percolate down to substitute the depleting deep aquifer water due to releases through the artesian wells. The downward percolating fresh groundwater will becomes brackish due to the saline nature of the deep aquifers (Figure 8).

Such uncontrolled artesian wells discharges will cause further damage to the thermal mineralized groundwater, to fresh surface watercourses and to the environment. Water sector actions are deeply required to stop the deterioration caused by the irresponsible actions of not sealing and closing these unnecessary wells.

Thermal mineralized springs in Jordan issue along steeply incised side wadis in the eastern escarpment of the Jordan Rift Valley. Generally, the groundwater bodies from which and where they issue are free water table aquifers. Therefore, the groundwater sources in the up-gradient areas of their discharge sites are vulnerable to any human activity producing pollution. As an example, Madaba wastewater treatment plant, which discharges its treated wastewater into the up-stream area of Wadi Zarqa Ma’in and which, with time, find its way through the upper parts of the unconfined aquifer to the thermal mineralized groundwater in the same aquifer.

Himma thermal mineralized springs at the southern bank of the Yarmouk River are also highly threatened by the human activities in El-Himma village and its surroundings such as urbanization, without proper sanitation and lack of sewerage systems and wastewater treatment and reuse schemes, agricultural, and small industries activities. Since about 20 yr., fecal bacteria and other microorganisms have been detected in the spring’s water of up to a few hundred fecal bacterial counts per milliliter.

Delineation of protection zones and enforcement of their application have now become an imperative in many areas of the thermal mineralized springs in Jordan.