Abstract. Groundwater resources are precious commodity in general
and for arid regions in particular. Their exploration, exploitation,
protection and management play significant role in societal activities.
In the Kingdom of Saudi Arabia, extensive aquifers are available in
the Arabian Shelf. The Saq aquifer is one of the most important
aquifers in the northwestern part of Saudi Arabia. It is made up of a
Cambro-Ordovician sandstone formation, which extends over 1200
km in Saudi Arabia and northwards in Jordan. Groundwater occurs
under unconfined conditions in the southwestern part and changes to
confined conditions northward. The study area is located at about 50
km northwest of Tabuk, where many agricultural projects have been
established depending on groundwater of the Saq aquifer for
irrigation. The present study deals essentially with the hydrogeology
of the Saq aquifer and the impact of extensive pumping on both
groundwater levels and groundwater quality. Pumping and recovery
tests were carried out in order to estimate the aquifer parameters. A
total number of 192 groundwater samples were collected during the
period 2000-2004 for quality investigation. Results of analysis of
pumping test data showed that the average transmissivity and
storativity are 1572 m2
/day and 2.86 × 10-4, respectively. Values of
average TDS of groundwater range between 540 and 670 mg/l, which
indicate that it can be used safely for irrigation. The TDS values
showed general decrease towards the northeastern part of the study
area, in the direction of flow. Extensive pumping from 260 deep wells
with an average discharge rate of 0.015 m³/sec has resulted in
continuous groundwater level drop since 1999 with an average rate
ranges between 2.3 − 10.5 m/year. Additionally, the effects of
pumping on the water quality for the period 2000-2004 were studied