Strategic Groundwater Storage in Wadi Na’man, Makkah Region, Saudi Arabia
Majed Es-Saeed, Zekaï Şen, Ahmed Basamad, and Amro Dahlawi
Groundwater in the western part of the Red Sea coastal region is contained within Quaternary wadi deposits.
Much of the groundwater supplies the cities of western Saudi Arabia—Jeddah (the commercial center and port), Makkah Al-Mukharramah (the Holy Muslim city and focus of the Hajj Pilgrimage), and At-Taif (the resort city at more than 2,000 m above sea level).
The groundwater is part of the local hydrological cycle that is under the influence of a Mediterranean-type climate in winter and of monsoonal rainfall during spring.
Local geomorphologic features, such as the Red Sea and the 2,000-m-high northwest-trending Hijaz Escarpment, modify these climatic patterns.
The Escarpment and its foothills generate orographic rainfall that augments the cyclonic rainfall of the Mediterranean weather pattern to recharge the wadi alluvium aquifers.
In recent years, urban expansion of Jeddah, Makkah Al-Mukharramah, and At-Taif, and the increasing numbers of pilgrims visiting the Holy City, has led to extra pressure on already limited groundwater resources. As a result, the Saudi Geological Survey (SGS) is making a regional evaluation of the strategic groundwater resources of the most important wadis in the coastal region, namely Malakan, Na’man, Fatimah, Usfan, and Khulays. Wadi Na’man, which extends from the Hijaz Escarpment in the east to the Red Sea in the west, has supplied water to Makkah Al-Mukharramah city for more than 12 centuries.
This report presents the preliminary conclusions, methodologies, and recommendations for Wadi Na’man for use in a future regional optimum well location and groundwater resources management program.
For strategic planning purposes, this report identifies the aquifers in Wadi Na’man in terms of geometric, hydrologic, and hydrogeologic parameters, and water quality.
In addition to the natural constraints of low recharge on the aquifers, water demand peaks annually during the two holy periods of Ramadan and Hajj.
Although desalination plants along the Red Sea coast provide additional water, wadi groundwater is the sole reserve in the case of an emergency or higher than expected demand.
In addition, because the natural minerals in groundwater improve its taste, groundwater mixed with desalinated water provides acceptable potable water.
Due to a water scarcity, many local people are selling groundwater in an unregulated manner that may damage the aquifer and reduce the potential of the groundwater resources for future use. It is therefore necessary to take urgent political and/or administrative decisions for the rational use of the groundwater resources in Wadi Na’man.
This report provides the necessary preliminary study. Its general conclusions are as follows: Groundwater levels are falling continuously due to haphazard, unregulated pumping.
Wells are concentrated in areas identified by the experience of local people; consequently, there is interference between wells due to unregulated well-sinking and pumping.
Annual rainfall in the Wadi Na’man catchment area is about 770 million m3.
The cumulative available abstractable groundwater between upstream Wadi Na’man and the confluence with Wadi Uranah is about 1,450 million m3. The cumulative rechargeable groundwater storage for the same area is about 1,970 million m3.The three main water supply locations are (i) upstream from the Wadi Ar’ar confluence; (ii) the Ain-Zubaidah area near to the Arafat Police Check Point; and (iii) Wadi Rahjan.
Annual abstractions are 5.52 million m3, 3.05 million m3, and 2.50 million m3, respectively.
Pumping from municipal wells close to the Arafat Police Check Point is about 2.5 million m3 per year and from local wells is about 3 million m3 per year.
This causes a high hydraulic gradient and consequently requires a high-velocity groundwater flow from Ain-Zubaidah and upper Wadi Na’man to maintain pumping rates.About 70 percent (approximately 11 million m3) of all abstracted water is for domestic purposes; the remainder is for agricultural use.
Uncontrolled pumping from the lower Ain-Zubaidah sector near to the Arafat Police Check Point may cause saline water intrusion from Wadi Uranah.
Recommendations based on the extensive field and office studies are as follows: Confine abstraction and storage locations to the area upstream of the Wadi Na’man-Wadi Uranah confluence.
Construct a major subsurface dam in upper Wadi Na’man immediately below the confluence with Wadi Ar’ar to collect groundwater from wadis Ash Shara, Yaruj, Majarish, and Ar’ar.
The design should allow for the drainage of saline water beneath the dam.
Construct a smaller subsurface dam upstream from the confluence with Wadi Uranah and near to the Arafat Police Check Point.
This would provide: (a) groundwater recharge impoundment along an 8-km reach of the wadi; (b) capture overflow from the upstream subsurface dam; and (c) prevent intrusion of poor-quality downstream water due to salination, especially from Wadi Uranah.
Construct dikes, ditches, and terraces to increase groundwater recharge and reduce the harmful effects of flooding.
Water for agricultural purposes (4.6 million m3) constitutes almost 30 percent of the total volume abstracted from Wadi Na’man; minimize this amount by using controlled irrigation systems.
Restrict the number of wells depending on the overall safe yield, hydrogeological features, well interference, quality variations, and population concentrations.
Conserve some parts of the wadi aquifer for emergency exploitation and plan for emergency wells.
Determine the discharge volumes and life of wells through a simple, effective groundwater management program to take into consideration the arid conditions.
Establish a monitoring system using pumping wells and small diameter piezometer wells.
Es-Saeed, M., Şen, Z.Z., Basamad, A., and Dahlawi, A., 2004, Strategic groundwater storage in Wadi Na’man, Makkah region, Saudi Arabia: Saudi Geological Survey Technical Report SGS-TR-2004-1, 70 p., 65 figs. 24 tables, 5 apps.