Geophysical study and watershed hydrological delineation have been integrated at downstream of Alasra dam site Norh Azraq area to investigate their potential for artificial groundwater recharge. The total surface area of the watershed was found to be about 195 square kilometers. The estimated annual runoff volumes for the Alasra watershed ranged between 1.2 and 1.8 MCM. Moreover, the interpretation of Ten Time Domain Electromagnetic (TDEM) soundings suggested three principal subsurface layers. The top surface layer has an intermediate resistivity (90 - 110 Ohm·m) with a thickness ranging from a few meters to around 50 m. This layer was interpreted as superficial deposits. The second subsurface layer with variably high resistivity values is composed of unsaturated massive basalt layer and probably belongs to Madhala Olivine Phyric Basalt Formation (MOB). The large variations in resistivity could be ascribed to the degree of water saturation (as a result of groundwater recharge from the nearby harvested water dam), or lithological variations (clay content) and/or due to structural control. The third subsurface layer has low resistivity values (<10 Ω·m to 40 Ω·m) and was found at a depth ranging from 120 to 150 m. This layer could represent a saturated basalt layer with high clay contents. The subsurface structures and major faults have been identified. Based on the results of this study, a combination of surface and subsurface artificial groundwater recharge techniques is highly recommended.
Jordan is located in an arid to semi-arid region with variable topography features. The far western part of the country is mountainous terrains, while the eastern and southeastern parts are dominated by flat-desert terrains. Due to these topographic variations, rainfall distribution varies considerably. The annual rainfall intensity ranges from 600 mm in the northwest to less than 50 mm in eastern and southern parts of the country [
TDEM technique has been previously used in numerous hydrogeological applications (e.g. [
The investigated area- which is part of Jordan’s eastern plateau - is located in the northwestern part of Azraq basin between [480000 - 492000] E, [550000 - 575000] N according to Jordan Transverse Mercator (JTM) (
The geological setting of Neogene continental basalts exposed at NE-Jordan have been investigated by several researchers (e.g. [
It comprises thick and massive flow units up to 10 m with a total thickness of up to 100 m. It contains several basaltic flood lava and feeder dike systems and is characterized by a massive, blocky and, columnar joint with polygon upper surfaces. There is a strong vesicularity in the upper part of the flow edifices.
This formation was formed by eruption from the Jebel al Aritin volcano which flooded west- and south-wards along an old wadi. It typically displays well developed columnar jointing and non-systematic closely spaced horizontal jointing. It has host mantle xenolith.
Lava of the formation is extruded from the central vent of the Jabal Ushayhib volcano and the associated parasitic volcanoes. It forms an upstanding semi-vertical cliff above the plain of the Abed Olivine Phyric Basalt Formation (AOB) with up to 15 m thick.
Similar to Ufayhim Formation, the Hashimyya Formation typically displays columnar jointing, and less developed non-systematic closely spaced horizontal jointing. It is characterized by the presence of volcaniclastic deposits underneath. The thickness of Hashimyya Formation is less than 15 m and comprises thin flow units mostly ranges between 3 and 5 m. it is characterized by the presence of amygdaloidal texture, where vesicles are filled with calcite.
Lava of Madhala Olivine Phyric Basalt Formation erupted from volcanic vent centers, including shield volcanoes, composite volcano vents and cinder scoria cones in the area. Its thickness varies greatly and reaches its maximum 100 m around the volcanic vents. It is mainly consists of massive and bedded basalt with polygonal joints, vesicles are present. There are large similarities between its lithology and the Abed Olivine Phyric Basal Formation.
It differs from the other units of the Asfar group in its hummocky and rough upper surface which comprises weathered wadi-fill lava with poorly preserved pressure ridges. The thickness of the formation varies from 10m to 25 m. It is lithologically similar to Madhala Olivine Phyric Basalt Formation.
The 15 - 40 m deposits of Hassan Formation include bombs of lava spatter with various shapes along with coarse scoriaceous blocks. It is composed of poorly bedded, friable and very coarse-grained scoriaceous pyroclasts.
The Aritayn Volcaniclastic Formation is developed from stratified cinder cones, occasionally composite. These pyroclastic deposits interbedded with lava flows. The formation consists of bedded, poorly cemented air-fall tephra, which is typified by its stratified form and typically cavernous. Similar to the Hassan formation, it is characterized by a smooth ground surface color. The boulder cover is mainly pyroclasts mixed with basaltic boulders.
This group includes the youngest volcanism recorded in the study area. It is subdivided into two formations based on truncation flow lines which is a reflection of different ages, otherwise, the area is lithologically and morphological similar. These are Fahda Vesicular Basal Formation (FA) and Wadi Manasif Basalt Formation (WMF) which are not shown in the investigated area. The surface of the flows is characterized by a rubbly and very vesicular ground cover. Boulders are characterized by a purplish-black weathering color. They show a columnar jointing and exhibit typical polygonal lobes of pahoehoe lava types. This group has a thickness ranging from 25 - 60 m.
Alluvium and wadi sediments consist of gravels and, sand deposits.
Alluvial fans occur in two places, to the southeast of Jabal Al Aritin and south of Wadi Al Aritin. The fans are composed of stony, or sometimes boulder, deposits with arcuate low ridges of gravels, sand and silt.
Several mudflats are surrounding the investigated area. They were probably formed as a result of regional and local faults which produced small depressions, where mud accumulated from standing water fed by ephemeral wades discharged into the mudflat. They consist of soft and silty clay and rock fragments.
The watershed model of Alasra site (
A preliminary runoff investigation for part of Alasra site was conducted by [
In the downstream of Alasra harvested dam site (
Sounding | Longitude | Latitude | Elevation | RMSE (%) |
---|---|---|---|---|
TDEM-1 | 485153 | 552067 | 724 | 1.85 |
TDEM-2 | 485169 | 551802 | 715 | 3.09 |
TDEM-3 | 485198 | 551576 | 710 | 1.31 |
TDEM-4 | 485224 | 551410 | 718 | 5.62 |
TDEM-5 | 485448 | 551407 | 705 | 3.88 |
TDEM-6 | 485453 | 551573 | 703 | 6.74 |
TDEM-7 | 485498 | 551740 | 703 | 1.58 |
TDEM-8 | 485685 | 551830 | 735 | 2.75 |
TDEM-9 | 485686 | 551584 | 740 | 4.61 |
TDEM-10 | 485681 | 551331 | 735 | 5.46 |
order to avoid aliasing effects of possible galvanic interference. The system is comprising a Transmitter-Receive control and managed by HP-IPAQ Pocket system. TDEM measurements were analyzed using TEM RESEAR- CHER Software, a component of TEM FAST 48 HPC system. Data were processed by fitting the theoretical model with field data. TEM RESEARCHER Software enables to combine multi TDEM soundings in a 2-D cross section of resistivity distribution. It allows for interpreting TDEM data in a single curve (
TDEM’s sounding points have been individually interpreted as a 1-D layering model using the available surface and subsurface geological information and the static water level map of basaltic aquifer (
Sounding | Layer | Resistivity (Ohm∙m) | Thickness (m) | Suggested Geological Interpretation |
---|---|---|---|---|
TDEM-1 | 1 | 145.8 | 20.2 | Intermediate resistivity top soil (could be superfacial deposits, Alm/Alf/Al and clay) |
2 | 80.6 | 12.3 | ||
3 | 165.4 | 20 | ||
4 | 2000 | 17.5 | High resistivity layer composed of unsaturated basalt of MOB | |
5 | 82.4 | 10 | ||
6 | 4.06 | 20 | Low resistivity layer (Saturated basalt and clay) Unknown thickness | |
7 | 4.06 | |||
TDEM-2 | 1 | 97.99 | 19.6 | Intermediate resistivity top soil (could be superfacial deposits, Alm/Alf/Al and clay) |
2 | 2000 | 15.24 | High resistivity layer composed of unsaturated basalt of MOB | |
3 | 229.13 | 38.17 | Intermediate resistivity layer composed of Basalt with higher degree of saturation | |
4 | 309.56 | 10 | ||
5 | 37.85 | 30 | Low-intermediate resistivity layer | |
6 | 37.85 | Low-intermediate resistivity layer (unknown thickness) | ||
TDEM-3 | 1 | 57.8 | 17.7 | Intermediate resistivity top soil (could be superfacial deposits, Alm/Alf/Al and clay) |
2 | 42 | 4 | ||
3 | 68.2 | 5.53 | ||
4 | 94.2 | 4.57 | ||
5 | 1672 | 12.5 | High resistivity layer composed of unsaturated basalt of MOB | |
6 | 760.8 | 63.1 | ||
7 | 33.6 | 10 | Intermediate to low resistivity top soil (could be saturate basalts and clay) | |
8 | 9.87 | Low resistivity with unknown thickness | ||
TDEM-4 | 1 | 64.4 | 13.8 | Intermediate to low resistivity top soil (could be saturate basalts and clay) |
2 | 29.6 | 3.78 | ||
3 | 32.3 | 8.14 | ||
4 | 38.9 | 4.49 | ||
5 | 1430 | 11.2 | High resistivity layer composed of unsaturated basalt of MOB | |
6 | 2000 | 23.8 | ||
7 | 19.6 | |||
TDEM-5 | 1 | 70 | 18.1 | Intermediate resistivity |
2 | 2000 | 76 | High resistivity layer composed of unsaturated basalt of MOB | |
3 | 38 | 7.58 | Low-intermediate resistivity layer (thickness > 30 m) | |
4 | 26 | 20 | ||
5 | 23.3 |
TDEM-6 | 1 | 133.3 | 27.18 | Intermediate resistivity top soil (could be superfacial deposits, Alm/Alf/Al and clay) |
---|---|---|---|---|
2 | 2000 | 56 | High resistivity layer composed of unsaturated basalt of MOB | |
3 | 32.56 | 26.3 | Low-intermediate resistivity layer (thickness > 30 m) | |
4 | 10.93 | 10 | ||
5 | 3.1 | 20 | Low resistivity layer (thickness > 20 m) | |
6 | 3.1 | |||
TDEM-7 | 1 | 106.5 | 24.4 | Intermediate resistivity top soil (could be superfacial deposits, Alm/Alf/Al and clay) |
2 | 311.7 | 13.7 | ||
3 | 207 | 22 | ||
4 | 123.8 | 27 | ||
5 | 95.5 | 17.8 | Intermediate resistivity layer composed of Basalt with higher degree of saturation | |
6 | 43.3 | 10 | ||
7 | 14.4 | 10 | Low-intermediate resistivity (resistivity > 15 m) | |
8 | 14.4 | |||
TDEM-8 | 1 | 117 | 18.6 | Intermediate resistivity zone composed of basalt and superfacial deposits (alluvium mudflat and clay) |
2 | 42 | 16.7 | ||
3 | 64 | 6.54 | ||
4 | 188.6 | 10.6 | High resistivity layer composed of unsaturated basalt of MOB | |
5 | 2000 | 50 | ||
6 | 10.1 | Low resistivity layer with unknown thickness (saturated layer and clay) | ||
TDEM-9 | 1 | 87.3 | 24 | Intermediate resistivity zone composed of basalt and superfacial deposits (alluvium mudflat and clay) |
2 | 78.5 | 5.84 | ||
3 | 267.2 | 10.4 | High resistivity layer composed of unsaturated basalt of MOB | |
4 | 2000 | 21.6 | ||
5 | 141 | 10 | Intermediate resistivity | |
6 | 7.57 | 20 | Low resistivity layer (saturated layer) Unknown thickness | |
7 | 7.57 | |||
TDEM10 | 1 | 34.39 | 11.2 | Intermediate resistivity zone composed of basalt and superfacial deposits (alluvium mudflat and clay) |
2 | 2000 | 49 | High resistivity layer composed of unsaturated basalt of MOB | |
3 | 33.34 | 10 | Low resistivity layer (saturated layer) Unknown thickness | |
4 | 1.31 | 30 | ||
5 | 1.31 |
degree of saturation. Additionally, it was found that the same layer has a resistivity of 1000 Ω∙m at TDEM-3 and TDEM-4 (
There is probably a significant NNW-SSE fault identified at different cross-sections, between TDEM-7 and TDEM-8 (
matic maps at different depths (
There are several artificial groundwater techniques that have been developed and applied in various parts of the world. The description of these methods is mentioned in [
1) Direct Surface Recharge: It is the simplest and most widely applied technique. In this method, water moves from the land surface to the aquifer by means of percolation through the soil. It has relatively low construction costs and is easy to operate and maintain. However, this technique cannot be applied in the study area for the following reasons:
a) It requires longer time for the recharge water to reach the aquifer. This might lead to evaporation problem, especially in arid environment as that of the study area, where the evaporation rate is high.
b) The groundwater aquifer in the study area is deep (above 150 m) which means that the surface water will need more time to reach the groundwater.
c) There are indications of a clay layer above the water table in the study area which prevents the groundwater
recharge using such technique.
2) Direct Subsurface Recharge: This technique is used for recharging deeper aquifers which is the case within the study area. It is based on digging injection wells when aquifers are deep and separated from the land surface by low permeability materials. This technique is expensive but might be a solution to replenish groundwater in the study area. The problem with the clay layer above the groundwater table can be overcome by digging injection wells to penetrate this layer and establish a path between surface and the groundwater.
3) Combining Surface-Subsurface Methods: Both techniques mentioned above could be combined to have a better groundwater recharge. The surface water dam in the area could help in applying a direct surface recharge through the wadi bed. Also, having injection wells close to the dam will accelerate and maximize the potentials for replenishing the groundwater in the area.
This research was carried out by Hani Al-Amoush while on sabbatical leave from Al al-Bayt University for the academic year (2015/2016). The authors would like to thank Al al-Bayt university presidency, the dean of Institute of Earth and Environmental Sciences. The authors also acknowledge the help and supports of the dean and staff of The Scientific Research Deanship at Al al-Bayt University. Critical and constructive review of the manuscript by the reviewers is greatly treasured.
Hani Al-Amoush,Abdel Rahman Al-Shabeeb,Saad Al-Ayyash,Rida Al-Adamat,Majed Ibrahim,A’kif Al-Fugara,Jaafar Abu Rajab, (2016) Geophysical and Hydrological Investigations of the Northern Wadis Area of Azraq Basin for Groundwater Artificial Recharge Purposes. International Journal of Geosciences,07,744-760. doi: 10.4236/ijg.2016.75057