This basin, in its broad definition, includes the Paleozoic and Mesozoic aquifers in the south and the Neogene aquifers in the north. It extends over a surface area of more than 2.2 million km2, 760,000 km2 of which are in Libya. It is locally known as the Kufra and Sarir Basins, and has been used since the mid-1960s and early 1970s in the supply of local water requirements and the irrigation of major agricultural projects in Kufra and Sarir. This basin also supplies water for oil production activities, and more recently for the GMRP conveyance system. In Egypt the area of the Nubian Basin is of the order of 828,000 km2, while it is limited to only 376,000 km2 in the Sudan and 235,000 km2 in Chad.
In Libya, the basin has been subjected to a number of local studies accompanied by deep exploratory drilling and extensive geological and geophysical surveys. The generated results helped in the determination of hydraulic properties and flow direction, and for setting a base for the continuous monitoring through a piezometric network of more than 150 wells.
This network has enabled the construction of advanced mathematical models to study future aquifer behaviour. Figure 3 shows the local extension of the Kufra and Sarir aquifers.
The Kufra Basin
The Kufra basin covers an area of over 200,000 km2 and consists of a deep Paleozoic aquifer and a more widely used upper aquifer known as the Nubian Sandstone. The saturated thickness of both aquifers exceeds 3,000 m in the central part of the basin south of Kufra town. Production wells drilled for agricultural water supply range in depth from 400 m to 500 m with productivity ranging from 100 m3/hr to 300 m3/hr and a water quality between 180 mg/l and 300 mg/l. Transmissivity from pumping tests falls between 300 and 3500 m2 /day.
Storativity is in the order of 0.0001 and 0.015.
ﻣ ﺻ ر
40N 15W 10W 5W 0 5E 10E
15E 20E 25E 30E 35E 40E 35N
30N 25N 20N 15N 10N
5N
Figure 3. Nubian Sandstone Basin in Libya
To the north of Kufra, Tazerbu well field was completed in depths ranging from 450 m to 600 m, with productivity reaching 400 m3/hr and water quality of less than 500 mg/l.
Tazerbu wells are tapping the lower aquifer (Paleozoic). Both aquifers are hydraulically connected at the regional level and are also in contact with the Miocene aquifer in the Sarir Basin to the north. Groundwater flow is from south to north and northeast in the direction of the natural depressions along the latitude 30 N such as the Qattara Depression in Egypt.
The Sarir Basin
Located to the north of the Kufra Basin, the Sarir Basin covers a surface area of more than 450,000 km2 and consists of a number of aquifers belonging to the Post-Eocene. The basin is currently developed for agricultural activities in the Sarir area as well as for conveying water to the northern plains. Depth of wells tapping these aquifers range from 400 to 500 m with productivity varying from 150 to 300 m3/hr and water quality in the order of 1200 mg/l.
Transmissivity and storativity determined from pumping tests fall between 750 and 1500 m2/day and 0.0005 and 0.0001 respectively.
The Joint Commission for the Study and Development of the Nubian Sandstone Aquifer
The hydrogeological studies and mathematical models that were conducted on the Nubian Sandstone aquifer in Libya have shown that large quantities of water are available for development for many decades to come. These studies also emphasized the need to determine
Kufra
Sarir
enable the representation of its future behavior in accordance with the development schemes of the sharing countries.
The announcement of the creation of a Joint Commission for the coordination between Libya and Egypt in managing the shared groundwater aquifer was made in Tobruk during the summit meeting on 17 October 1989. The establishment protocol was signed during the third round of the Libyan-Egyptian Joint Committee meeting and members of the board of the joint commission were nominated. The internal code determined the objectives and functions of the commission as follows:
1. Collection of data, information and study results from concerned countries for classification, analysis and linkage.
2. Complementary studies to determine the present state of the aquifer from the qualitative and quantitative point of view.
3. Preparation of plans for the development of water resources and the proposal and implementation of joint policies for the exploitation and use of water resources at national and regional levels.
4. Management of the aquifer on sound scientific bases.
5. Cooperation in the field of training and capacity-building.
6. Call for rational use of the Nubian Sandstone aquifer water.
7. Study of environmental impacts of water development.
8. Organization of scientific workshops and dissemination of aquifer-related information and strengthening of ties with regional and international organizations of common interest.
Both Sudan and Chad joined the Commission at a later stage and became full members. The Commission has held six meetings, most of which were dedicated to the exchange of information and scientific data and follow up of the work progress in the Nubian Sandstone Aquifer System (NSAS) project.
The Nubian Sandstone Aquifer System Study Project
The Nubian Sandstone Aquifer System Study Project began in 1998 with the Center for Environment and Development in the Arab Region and Europe (CEDARE) as an executing agency. The project is financed in its first phase by the International Fund for Agricultural Development (IFAD) and with contributions from the concerned countries. It aims at reviewing previous studies, establishing a regional data base and preparing a mathematical model capable of representing the aquifer condition and simulating its future behaviour in response to planned development schemes. The model is also expected to study the effect of future withdrawals on water levels and the extension of drawdown cones in neighbouring countries. The project also aims at training national teams in the different activities of the study including the application of the mathematical model, data bases, GIS, and the use of advanced monitoring equipment. Member countries were supplied with field and office equipment, instruments and software needed for data collection and interpretation. National teams prepared national reports reflecting the state of the aquifer in each country at an early stage of the project and during the preparation of the mathematical model, several meetings of country representatives were held at the level of technicians and decision-makers. The
meetings were dedicated for the validation of data, providing information needed for each stage of the model, approving model calibration, and determination of future development alternatives for the coming fifty years. This phase has been completed and a final report was produced. The present phase of the project covers socio-economic studies and is financed by the Islamic Development Bank (IDB).
Future Horizons
The Nubian Sandstone aquifer countries have succeeded in establishing a strong base for cooperation, which enables them to manage the basin in a sound and efficient manner. They realize the need for dealing with the basin as one hydrogeological unit and securing the flow of information. Future cooperation in the field of data collection and storage will enable member states to easily exchanging information and updating the regional mathematical model and allowing its use as an effective management tool. It is of utmost importance to continue the periodical monitoring of water levels and water quality. Improving legislation that guarantees the protection of the shared resources from pollution and overexploitation should also be given special attention.