TITLE:
Geophysical and Hydrological Investigations of the Northern Wadis Area of Azraq Basin for Groundwater Artificial Recharge Purposes
AUTHORS:
Hani Al-Amoush, Abdel Rahman Al-Shabeeb, Saad Al-Ayyash, Rida Al-Adamat, Majed Ibrahim, A’kif Al-Fugara, Jaafar Abu Rajab
KEYWORDS:
TDEM, Groundwater Recharge, Alasra, Hydrogeophysics, Azraq, Jordan
JOURNAL NAME:
International Journal of Geosciences,
Vol.7 No.5,
May
27,
2016
ABSTRACT: 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 (·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.