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Programme for the Development of a Regional Strategy for the Utilisation of the Nubian Sandstone Aquifer System ___________________________________________________________________________

Regional Strategy for the Utilisation of The Nubian Sandstone Aquifer System

Volume I

Executive Summary

CENTRE FOR ENVIRONMENT & DEVELOPMENT FOR THE ARAB REGION AND EUROPE

INTERNATIONAL FUND FOR AGRICULTURAL DEVELOPMENT

Preface

Throughout history, access to water has been essential to social and economic development and stability of cultures and civilizations. Water is an indispensable commodity of life. Groundwater is considered as one of the principal fresh water resources. Under the thrust of the ever-increasing population in the world, there happens to be a notable deficiency in the fresh water supplies. This state of affairs urged individuals, communities, authorities and international agencies to search for groundwater in an attempt to keep pace with the continually increasing demand for water. The countries of Northeast Africa, Egypt, Libya, Chad and Sudan share The Nubian Sandstone Aquifer System (NSAS), which represents a huge fresh water reserve. The four countries have expressed their interest to share their experiences and to develop this regional Aquifer System. With this in mind The Centre for Environment and Development for the Arab Region and Europe (CEDARE) developed a programme for The Development of The Nubian Sandstone Aquifer System. The Programme was then funded by the International Fund for Agricultural Development (IFAD) and executed by CEDARE. The results of the study presented in this report have produced a Regional Strategy for the utilization of this huge common resource, which hopefully will facilitate consultation between the concerned countries and create a sense of sharing a common resource in order to exploit it rationally. This detailed study has been conducted by a team of experts guided by Dr. Mohamed Bakhbakhi NSAS Regional Coordinator. May I avail myself to this opportunity to thank the collaborating national institutions for their efforts and cooperation. Last but not least I wish to express, on behalf of the governments concerned, and on behalf of CEDARE, our deep appreciation and gratitude to IFAD for financing the project. Dr. Kamal A. SABET

Executive Director

Acknowledgments

The “Programme for the Development of a Regional Strategy for the Utilisation of the Nubian Sandstone Aquifer System (NSAS)” is funded by the International Fund for Agricultural Development (IFAD). The execution of the Programme is the primary responsibility of CEDARE. The NSAS Programme team wish to extend their thanks and appreciation to IFAD who has funded this programme and made this publication and the associated study possible. They wish also to express their gratitude to CEDARE for hosting the Programme and making its implementation come true. The guidance and support of Dr. Kamal Sabet, Executive Director of CEDARE is highly appreciated. The NSAS Programme wish also to convey its gratefulness to the consultants of the Programme whose valuable inputs are highly appreciated, namely Dr. Abdou Shata, Senior Geology Consultant, Mr. Philippe Pallas, Dr. G. Pizzi and Eng. Saleh Nour. The Programme acknowledges the involvement and the effective contribution of the National Institutions of the four concerned countries whose cooperation, interaction and provision of information throughout the implementation of the Programme was of ultimate benefit and utmost importance towards the forwarding and accomplishment of this study. Special vote of thanks are to the National Coordinators; Dr. Moussa Terap – Chad, Dr. Fatma Attia – Egypt, Dr. Omar Salem – Libya and Dr. Idris M. Idris – Sudan. Appreciation is extended to all the members of the Steering Committee and the Regional Technical Review Committee for their constructive input and time. Special recognition to Ms. Sahar Ezz El Arab, Secretary of the Programme for typing the report. NSAS Programme Staff Dr. Mohammed Bakhabakhi Hydrogeologist (Regional Coordinator) Eng. Amr Abdel-Meguid Water Resources Engineer Eng. Omar Elbadawy GIS Specialist

Forward

This study on the development of a regional strategy for the utilization of the Nubian Sandstone Aquifer System has been prepared by Dr. Mohamed Bakhbakhi (CEDARE Regional Programme Coordinator), the Programme’s team of consultants, Professor Dr. A. Shata, Mr. Phillipe Pallas, Dr. G. Pizzi and Engineer Saleh Nour and the staff of The Programme Engineer Amr Abdel-Meguid and Engineer Omar Elbadawy. In the preparation of this study numerous reports, studies, documents, briefs and write up have been consulted. Below is a partial list of these reports: 1) The final reports of the “special research Project in Arid areas

period 1984 – 1987” and on “Hydrogeological investigations in the Nubian Aquifer System”, Eastern Sahara prepared by Klitzsch et al, 1987, as well as research on modeling of the Nubian Aquifer System by Heinl and Binkman (Published in 1989), the hydrogeological investigation carried out by Heinl and Thorweihe in Northern Sudan, 1983 and S.W. Egypt, 1993. (annex 1),

2) Bretschneider, H., Heinl, M., Brinkmann, P.J., Hollander, R. (1987) Groundwater Model for the Nubian Aquifer System. Technical University of Berlin.

3) The many technical reports prepared by the Technical University of Berlin and ACSAD upon request of OSS,

4) P.J. Brinkman, M. Heinl, R. Hollander and G. Reich, 1987. Retrospective simulation of groundwater flow and transport in the Nubian Aquifer System, Berliner Geowiss. Abh (A) 75.2, 465-516 Berlin.

5) JVQ, Joint Venture Qattara (1978): study Qattara-Depression, special volume: Regional geology and Hydrogeology, unpublished report of Lahmeyer GmbH, Salzgitter consult GmbH, Deutsche Projeckt Union GmbH.

6) Pallas P. (1978) water resources of the socialist People’s Libyan Arab Jamahiriya. 2nd Symposium of geology of Libya-Tripoli.

7) El Ramly, I. (1983), Water Resources Study of Zone V (Al Kufrah and Sirt Basins) unpublished report, Socialist People’s Libyan Arab Jamahiriya, Secretariate of Agricultural Reclamation and Land development, water and Soil Department.

8) The technical reports prepared by the National institutions and regional organizations (annex 1),

9) Ali Hissene Mahmoud (1986) geologie Und Hydrogeologie des Erdis-bechen, NE-Tschad. Berliner Geowiss. Reihe A/B 76, Berlin.

10) EZZAT, M.A . (1974): Groundwater series in the Arab Republic of Egypt; Exploitation of groundwater in El-Wadi El-Gadid Project Area. Part I to IV, General Desert Development Authority/ Ministry of Irrigation Cairo.

The results achieved during our study are included in a final report made up of four volumes and two annexes: Volume I Executive Summary including Executive Summary, and Recommendations, Volume II Hydrogeology including the geography, geomorphology, Geology and hydrogeology of The Project Area, Volume III Groundwater Mathematical Model includes the construction of The Model, the different simulations, and the main results of the Modeling activity, Volume IV Administration includes the administration report, Information System, Monitoring Network, Data exchange procedures Annexes:

Annex 1 – Information System Annex 2 – Bibliography

List of Abbreviations

ACSAD Arab Center for Studies of Arid zones & Dry Lands

Bm 3/y Billion cubic meters per year (109 m3/y)

CEDARE Centre for Environment and Development For the Arab Region and Europe

EIA Environmental Impact Assessment

GIS Geographic Information System

GWA General Water Authority, Libya

IFAD International Fund for Agricultural Development, Rome

IDB Islamic Development Bank

m.b.g.l meters below ground level

m.a.s.l meters above mean sea level

m.b.s.l meters below mean sea level

MSL mean sea level

mg/l milligrams per liter

g/l grams per liter

Mm3/y Million cubic meters per year

Mm3/day Million cubic meters per day

GMS Ground water Modeling System

AQUQA3D Ground water Modeling Software

NSAS Nubian Sandstone Aquifer System

NAS Nubian Aquifer System

PNAS Post Nubian Aquifer System

RC Regional Coordinator

RIGW Research Institute for Groundwater – Egypt

RPSC Regional Programme Steering Committee

RTRC Regional Technical Review Committee

SSO Sahara & Sahel Observatory

TDS Total Dissolved Solids

TUB Technical University of Berlin

UNEP United Nations Environmental Programme

UNDP United Nations Development Programme

U.S.G.S United State Geological Survey

mcm Million Cubic meters

PPM Parts per Million

GL Ground Level

a

TABLE OF CONTENTS

1. Introduction 1

1.1 Location ...................................................................................................................1 1.2 Background..............................................................................................................1 1.3 Objectives .................................................................................................................3 1.4 Scope of Work .........................................................................................................3

2. Regional Groundwater Development Strategy

2.1 Compilation and synthesis of existing information .................................................6 2.1.1 Geography.......................................................................................................6 2.1.2 Geomorphology and Hydrography .................................................................9 2.1.3 Geology ........................................................................................................ 11 2.1.4 Hydrogeology................................................................................................ 25

2.2 Mathematical Modeling ......................................................................................... 55 3. Recommendations........................................................................................................ 64

b

List of Figures

Figure 1 – General Location Map of Project Area........................................................................2

Figure 2 – Road map.....................................................................................................................7

Figure 3 – Aridity map and Average Annual Rainfall mm/year ..................................................8

Figure 4 – Watershed areas, and drainage basins .........................................................................10

Figure 5 – Regional Geology........................................................................................................12

Figure 6 – South – North Geological Cross -Section A -A'............................................................13

Figure 7 – Basement relief Map (datum sea level) .......................................................................14

Figure 8 – Paleozoic Arches and Basins.......................................................................................16

Figure 9 – Paleozoic Isopach Map................................................................................................17

Figure 10 – Mesozoic Isopach Map..............................................................................................20

Figure 11 – Cenozoic Isopach Map ..............................................................................................23

Figure 12 – Local Structural Elements .........................................................................................24

Figure 13 – South-North Hydrogeological Cross-Section B-B' ...................................................28

Figure 14 – West-East Hydrogeological Cross-Section C-C' .......................................................29

Figure 15 – Lateral and Vertical boundaries of The Nubian Aquifer System .............................32

Figure 16 – Transmissivity Map of the Nubian Aquifer System..................................................35

Figure 17 – Extraction Zones of the Nubian Aquifer System ......................................................36

Figure 18 – Water Production Histogram of the Kharga Oasis ....................................................40

Figure 19 – Water Level Iso-decline Contour map in Kharga Oasis (1966-1998) .......................41

Figure 20 – Water Production Histogram of the Kufra Projects Areas ........................................40

Figure 21 – Water Level Iso-decline Contour map in Kufra Projects Area. (1972-1998) ...........42

Figure 22 – Iso-Salinity Contour Map of the Top of the Nubian Aquifer System .......................43

Figure 23 – Lateral and Vertical boundaries of The Post Nubian Aquifer System......................46

Figure 24 – Transmissivity Map of the Post Nubian Aquifer System..........................................49

Figure 25 – Extraction Zones of the Pos t Nubian Aquifer System...............................................50

Figure 26 – Water Level Iso-Decline Contour Map in Sarir Projects Area (1975/77-1998) .......54

Figure 27 – Simulation 11 – Nubian – Drawdown (2000 - 2060) ................................................60

Figure 28 – Simulation 11 – Post Nubian – Drawdown (2000 - 2060) ........................................62

c

List of Tables

Table 1 – Paleozoic: Lithostratigraphy and Paleogeography .....................................................18

Table 2 – Mesozoic: Lithostratigraphy and Paleogeography .....................................................21

Table 3 – Cenozoic: Lithostratigraphy and Paleogeography ......................................................26

Table 4 – Lithostratigraphic Units of the Nubian Aquifer System .............................................30

Table 5 – Average Hydraulic Parameters of the Nubian Aquifer System..................................34

Table 6 – Groundwater Abstraction from the Nubian Aquifer System in Development Areas.. 37

Table 7 – Lithostratigraphic Units of the Post Nubian Aquifer System ....................................45

Table 8 – Average Hydraulic Parameters of the Post Nubian Aquifer System ..........................48

Table 9 – Groundwater Abstaction from the Post Nubian Aquifer System ................................52

Table 10 – Storage Capacity of the Nubian Aquifer System .......................................................56

Table 11 – Total Recoverable Groundwater Volumes from the Nubian Aquifer System ............57

Table 12 – Storage Capacity of the Post Nubian Aquifer System and Recoverable Volumes.....58

Table 13 – Highest development scenario from the Nubian Aquifer System –

Results of the Model ............................................................................................61

Introduction

Introduction

1.1 LOCATION The Nubian Sandstone Aquifer Systems (NSAS) underlies an area in excess of 2.5 million km2 within The Eastern Sahara in North-East Africa (Figure 1). The area occupied by The Aquifer Systems under study, known here as the Project Area is 2.2 million km2 and extends between Latitude 14º and 33º and longitude 19º and 34º to cover in Egypt 828,000 km2, in The Western Desert, including the area known as Wadi El Gedid. In Libya it covers an area of 760,000 km2, in the eastern part of the country to include, Kufra, Tazerbo and Sarir basins all the way to the Mediterranean Sea. In Sudan, The study area covers 376,000 km2, in Northern Darfur, and Northern Province to include the Sahara Nubian basin and part of the Nile Nubian basin. In North Chad, the Study area covers 235,000 km2. 1.2 BACKGROUND During the past four decades, Egypt, Libya and Sudan have made separate attempts to develop the Nubian Aquifer System and the overlying Arid lands. Since early seventies, The three countries have expressed their interest in regional cooperation to share their experience and to study and develop this regional aquifer. They agreed to form a Joint Authority to study and develop the Nubian Sandstone Aquifer systems and also agreed to seek international technical assistance to establish a regional project in order to develop a regional strategy for the utilisation of the Nubian Sandstone Aquifer System. The Centre for Environment and Development for the Arab Region and Europe (CEDARE), The Sahara and Sahel Observatory (SSO) and The International Fund for Agricultural Development (IFAD), among others joined forces to develop a programme for the Development of the Nubian Sandstone Aquifer System. IFAD organized several meetings attended by CEDARE as well as representatives of Egypt, Libya and Sudan. After the success of the preparatory phase where a regional programme document was prepared, consisting of three phases: phase one is setting Base for a Sustainable Development Strategy, phase two Identification and Formulation of Development Projects and phase three Implementation of Development Projects. The Governing Board of IFAD approved funding two-year programme to cover most of the activities of phase one described in the Regional programme document, in order to develop a Regional Strategy for the utilisation of the Nubian sandstone Aquifer System. CEDARE, The Executing Agency of The Programme.

Introduction

1.3 PROGRAMME OBJECTIVES The Programme’s objective is the formulation of a regional strategy for the sustainable utilisation of the Nubian Sandstone Aquifer System. This is achieved through the Programm’s specific objectives, which are;

i. create an enabling environment for the formulation of a regional development strategy.

ii. assist in the capacity-building of the national institutions in the concerned countries.

iii. Formulate a regional groundwater development strategy aimed at optimising levels of groundwater withdrawal from the Nubian Sandstone Aquifer System in each country in order to avoid any negative reciprocal externalities. 1.4 SCOPE OF WORK 1.4.1 Creation of an enabling Environment The Joint Authority of the Nubian Sandstone Aquifer that was previously formed between Egypt, Libya and Sudan was revitalized again in order to provide a coordination and cooperation mechanism for consultation among the concerned countries. Chad was officially invited to join the Authority. In March 1999 Chad actually became an active member of the Authority. During the 2 years lifetime of the Programme the Joint Authority met 4 times. The Joint Authority has:

1. appointed in their first meeting the Focal Point institutions which would coordinate the programme’s activities at National levels in each country, these institutions are in Egypt, The Research Institute for Groundwater (RIGW) of The Ministry of Irrigation and Water Resources. In Libya, The General Water Authority, in Sudan The Groundwater and Wadis Directorate of The Ministry of Irrigation and Water Resources and in Chad Direction de Hydraulique of the Ministere de l’Environment et de l’Eau

2. nominated two of its members in each country to act as the Regional Programme Steering Committee (RPSC). RPSC task is:

• approve the Programme’s Work Plan and Budget • review the achievements of the Programme and facilitate its implementation

3. approved a Provisional list of committee members proposed by CEDARE to act as The Regional Technical Review Committee (RTRC). The list includes representative of Egypt, Libya and Sudan (National Coordinators), CEDARE, IFAD, IDB, UNESCO, ACSAD, OSS, and The Technical University of Berlin. RTRC will :

• prepare the Work Plan and Budget • review the achievements of the Programme and facilitate its implementation • update the RPSC on the Progress of the Programme

4. appointed The Regional Programme National Coordinators to: • reflect their concerned countries views • update their countries members in the Joint Authority • implement the programme activities on the national level

Introduction

5. approved the process and the final choice of the regional Programme Coordinator The Joint Authority acted as a “clearing house” for the review and approval of the Annual Work Plan and Budget prepared by The RTRC. This resulted in an Institutional Arrangement that facilitated the implementation of the Programme on national level and regional level. For sustainable development and proper management of the NSAS, continuous monitoring of the aquifer should be maintained and monitored parameters should be shared between the concerned countries. The NSAS Programme has proposed a regional monitoring network, indicating representative sites that should be monitored, the parameters and the frequency of monitoring of these parameters. The four concerned countries sharing the resources represented by their National Coordinators adapted the regional monitoring Network and agreed to continue the monitoring of the Aquifer and to share the obtained information among them through a mechanism specified in two separate agreements. The Joint Authority as a permanent international organization founded by the four countries sharing the NSAS should be reinforced by both legislative and institutional mechanisms in order to enhance the cooperation among the countries sharing the Nubian Basins. 1.4.2 Capacity – building This consisted of purchase of equipment and training. 1. Purchase of Equipment

Purchase of Equipment for the focal point institutions in the three countries Egypt, Libya and Sudan. Chad was not included in the Programme’s budget, because of the late joining of the Joint Authority and the Programme. Never the less Chad benefited from the training programme and the purchase of some software. 8 computers, 4 colored printers, 8 GPS, 26 data loggers, four water level props, four EC/Temp/PH probes, three field computers, three GIS Digitizers and one Ao plotter were purchased and distributed among the three countries of equal cost except for 2 computers, one printer and the Ao plotter were kept at CEDARE for the utilization of the NSAS Programme. As far as the software concerned, all the computers purchased were loaded with basic word processing, spreadsheet, and presentation package. A Groundwater Modeling System (GMS) which is a software package includes several modules namely, Subsurface characterization, Map, Grid, ModFlow, MT3D and Geostatistics, was purchased. Later on a groundwater-modeling package called AQUA3D which uses finite element was found more appropriate for the modeling of NSAS. AQUA3D was purchased for the Programme as well as the four concerned countries. GIS modules were also purchased for the three countries to provide Data Automation, Mapping, Viewing Spatially Varying Information layers and spatial analysis of information layers. All of the above mentioned software were continuously upgraded.

Introduction

2. Training

Five training courses were held during the life time of the programme covering basic GIS and groundwater modeling and advanced training in GIS and groundwater modeling, plus a training course on installation and use of the monitoring equipment.

Regional Groundwater Development Strategy


2.1 COMPILATION AND SYNTHESIS OF INFORMATION : Data and Information were obtained from the previous literature and studies, and data collected by the focal point institutions in each country and/or by other local and international institutions that carried out extensive research in the area, were all inventoried, assessed, verified and digitized. The verified data was reformated, harmorized and standerdized then stored in a unified form using spread sheets for easy use and analysis purposes. This information include:

2.1.1 Geography

The Project Area, (Figure 1) occupying a portion of the great arid zone belt of North Africa, extends northward into the Mediterranean Steppe and merges on the southern side into the subtropical climatic zone. The surface is essentially developed into extensive flat topped plateaux (about 500m a.s.l. and rising locally to 1000m a.s.l.). These are underlain either by light colored carbonate rocks or by dark colored sandstone rocks. The elevated plateaux alternate with low undulating plains (300m a.s.l.), which descend in places to near sea level. Locally in the south and east the surface is affected by rugged mountainous areas, which rise to more than 3000m a.s.l.. The Project Area is accessible by a good number of black roads and desert tracts (Figure 2), which furnish a reasonable link between the Human Settlement, scattered in that wild area. Excluding the dense populated area in the Nile Valley and the Mediterranean littoral, the number of inhabitants is much less than one million (less than one person/km2). The surface is generally barren with regard to soils and vegetation and is dominantly covered by extensive sand sheets and elongate dunes (Erg.). Local ancient lacustrine deposits (playas) and sabkhas are reported in the depression areas. The Qattara Depression (140m b.s.l.), is one of the great negative landforms on the earth crust and it characterises the northern portion of the Project Area. In addition to that the River Nile is the only permanent river in that arid areas, the surface is dissected in several places by complex dry drainage systems, which reflect the present arid nature of the climate (Figure 3). Prior to that the climatic condition were less arid or even wet. The following is a brief account of such wet climatic conditions affecting the Project Area since late Pleistocene times:

• a great pluvial phase (120,000 to about 18,000 years BP); • a sub-pluvial (7000 to 5000 years BP); • a phase with declining and fluctuating climates (4350 to 3500 years BP); • a short wet phase (2800 to 2000 years BP)


2.1.2 Geomorphology and Hydrography The surface of the Project Area is developed into a number of five mega-watershed areas and mega drainage basins (Figure 4).

1. The mega watershed areas include :

• El Deffa – Baraka along the Mediterranean (200,000 km2), underlain by carbonate rocks, generally affected by strong to moderate winter rainfall and with drainage lines directed both to the sea on the north side and to the inland depressions on the south side,

• The Red Sea Mountain (150,000 km2). Touching the eastern portion of the Project Area, rising in places to more than 2000m a.s.l., and subjected both to winter and to summer mansoon rains. The surface is underlain by Basement rocks and is strongly dissected by deep wadis, a good number of which are directed to the Project Area.

• Tibesti (6000 km2). Touching the western portion of the Project Area, rising to more than 3000m a.s.l., underlain by hard rocks and strongly dissected by a complex pattern of drainage lines directed eastward to Kufra Basin and southward to Erdis Basin in Chad. Other Drainage lines are directed to Sarir Rebiana. Tibesti is affected occasionally by the subtropical summer rain and by the Mediterranean winter rain.

• Ennedi – El Gilf (460,000 km2); occupying much of the corner area between Chad, Sudan, Libya and Egypt. The surface, rising in places to more than 2000m a.s.l., is underlain by Basement rocks and by dark brown clastic sediments. The southern portion is crossed athwart by Murdi Depression, which is presumably a morphotectonic feature. The surface of this shed area is also dissected by a complex pattern of drainage lines which are directed both eastward to Salima – El Arabain low land areas (W. Howar and W. Al Juaifer) and westward to El Kufra – Erdis depressions. At El Gilf in the northern portions some of such wadis are vegetated (W. EL Ard El Akhadra).

• Maaza (or KurKur) – Maharik (179,000 km2). Stretching only in Egypt. The surface is essentially underlain by carbonate rocks and rises in places to about 500m a.s.l.. The surface is developed both into flat-topped plateaux (Hamada) and to rough undulating features (Kharafih). It is also scoured into a number of depression areas and is covered in places by shifting sands. Local playa deposits are also recognized on the surface. Although this shed area is also dead, the edges are dissected by short drainage lines, which designate the past-wet climatic conditions.

2. The mega drainage basins

The mega drainage basins are classified into internal and external basins. The internal basins are widespread and include the following:


• Qattata – Sarir (about 300,000 km2); affected by a variety of wadis directed from north to south, from west to east and from south to north. The surface is developed into extensive undulating plains, which are in many places below sea level. The surface is also dominantly covered by shifting sands, playa deposits and sabkha deposits and wet land areas.

• The Nile (about 200,000 km2), affected by the deep and extensive wadis draining the Red Sea Mountains and by the rather short wadis coming from the west. This basin is marked by the present valley of the Nile and by the High Dam Lake.

• Salima – Arabain (about 270,000 km2); little affected at present by wadis coming from west to east. The surface is developed into extensive sand sheet. Local playa deposits are dotted on the surface.

• El Kufra – Erdis (about 400,000 km2), affected by two main types of wadis; those coming from west to east and those coming from east to west. The surface is extensively covered by elongate sand duns and by ancient lacustrine deposits (playa).

2.1.3 Geology

2.1.3.1 General Outline

The regional geological framework of the Project Area constitutes a portion of the much wider area between Haggar massif in the west and the Red Sea massif in the east. This framework was originally established in Late Proterozoic times and was governed by the former plate tectonics affecting the area between Africa, Europe and Asia. The effect of the resulting stresses on the North African plate was the formation of basins, troughs, grabens, ridges, blocks and uplifted areas with different orientations. Volcanic eruptions followed many of the old lines and intrusion of granitic magma took place in the Lower Paleozoic. The oldest rocks exposed in the Project Area belong to the Precambrian and are referred to as the Basement rocks (Figure 5 & 6). These outcrop immediately to the south, east and southwest of the Project Area. Local exposures are also found at Oweinat area at the border between Egypt, Libya and Sudan. These Basement rocks are dominated by granites and granodiorites, in addition to an association of metasediments, metavolcanics, metagabros and serpentines. The Basement relief, as outlined by the long term geological and geophysical surveys is fairly well understood (Figure 7). Such rocks are overlain by a thick sedimentary section, which is here referred to as the Phanerozoic. The details about the stratigraphy of this section is given here below. 2.1.3.2Stratigraphy of the Phanerozoic Data about the stratigraphy of the Phanerozoic in the Project Area, is essentially obtained both from the published work (mainly Klizsch et al 1987; Said, 1990 and


Issawi, 1999) and also from a limited number of technical reports (maily Pallas, 1978 and El Ramly, 1983). The Phanerozoic succession (Figure 6), having cumulative thickness in excess of 15 kilometers, is distinct into two major units: • a lower unit dominated by sand facies mainly of epicontinental origin, and • an upper unit dominated by carbonate facies of marine origin. Using the geological time scale system in the description of the Phanerozoic section and avoiding all the local names given in the different countries to the stratigrphic units, the succession is differentiated into: • the Cenozoic on top, comprising the Paleocene, the Eocene, the Oligocene, the

Miocene, the Pliocene and the Quaternary, including the Pleistocene and the Holocene (about 5000m thick),

• the Mesozoic in the middle; comprising the Triassic, the Jurassic and the Cretaceous (about 7000m thick) and

• the Paleozoic at the base, comprising the Cambro-Ordovician, the Silurian, the Devonian, the Carboniferous and Permian (about 4000m thick).

The Paleozoic

As elsewhere in NE Africa, the regional framework of the Basement has a strong bearing upon the mode of deposition of the Paleozoic sediments in the Project Area. This framework became understood in view of the geophysical surveys and the deep boring for oil, especially in Libya and in Egypt. In the southern portion of the Project Area, the Paleozoic rocks crop out near the Basement Contact in Chad, Sudan, Libya and Egypt; but they sunk below the younger sediments in the north and northwest directions. One of the main structural features in the Project Area, during the Paleozoic, is the Bahareya–Oweinat–Enndi Arch, which divides the area into two unequal parts (Figure 8). Other arches are detected, both to the northwest and to the southeast and alternate with regional basins, having the same NE-SW orientation. Paleozoic rocks are exposed in SE Libya, SW Egypt, NW Sudan and NE Chad (Figure 5). The maximum reported thickness is of the order of 1500m in Ennedi in NE Chad. A thinner section of about 500m outcrops in Gebel Haweesh (Dalma) in SE Libya. The succession in both locations is dominated by fluviatile sand facies. Paleozoic rocks are reported in the subsurface, attain a maximum thickness of about 2000m. and are also dominated by sand facies. Paleozoic rocks are expected, from aero-magnetic surveys to exist in some other localities. Reference is especially made to SE Egypt (in the vicinity of Aswan), where the expected thickness is of the order of 3000m (Issawi, 1999). Figure 9 is a regional isopach map of the Paleozoic. From base to top the Paleozoic is differentiated into:

• The Cambro-Ordovician • The Silurian • The Devonian

• The Carboniferous, and • The Permean.

The details are indicated in (Table 1).

Characteristcs

LIBYA

Thickness (m) 300 to 1226m 30 - 400m 300 - 600 350 & 400mFacies fluviatile deltaic fluvial and aeolian fluvial and lacustrineType Locality Haweesh Arkeno & Kufra Tibesti and Kufra G. Oweinat

EGYPT

Thickness 13 to 1500 m 500 - 1300m 75 - 100m 50 - 400

Facies fluviatile & tidal flatsfluvioglacial & tidal flats fluviatile to marine

continentalType Locality El Gilf and Siwa Siwa Siwa and El Gilf Siwa & Qattara

SUDAN

Thickness 100m 30.0mFacies continental sub-tidal flats fluviatile continentalType Locality NW Sudan NW Sudan NW Sudan regional

CHADThickness 100m 600.00Facies fluviatile continental continentalType Locality Ennedi regional Tibesti regional

Table 1 - Paleozoic : Lithostratigraphy and Paleogeography

continental

300-540mcontinental

El Gilf and Siwa

STRATIGRAPHY

Permean

flucioglacial to shallow marine

Location

130 to 1100m

continentalregional

regional

Kufra

Cambro-Ordovician Silurian Devonian Caroniferous


The Mesozoic

At the close of the Paleozoic era, several geosynclinal seas were formed since the beginning of the Mesozoic (Late Jurassic times). Such seas accounted for two major transgressive phases in N. Africa: • during the Middle Mesozoic (Cenomanian), and • during the Late Mesozoic (Upper Senonian) A main regressive phase (with minor ingressions) took place at the beginning of the upper Mesozoic (Turonian and Lower Senonian). In the Project Area the surface exposures of the Mesozoic (Figure 5 and 6) occupy much of the southern portion (South of Latitude 27° N). The exposed section, having a maximum thickness of about 2000m, is differentiated into two main units: • a thick lower unit (about 1500m); dominated by epicontinental

sediments, and • an upper unit, having a thickness of about 500 m and is developed into

marine carbonates and shales, with thin phosphatic horizons. In the northern portion of the Project Area (north of latitude 27° N) the Mesozoic sediments are wide spread in the subsurface. Local exposures are only found in the domal structures of Abu Roash in the vicinity of Cairo City and of Bahareya, 300 km to the southwest. The Mesozoic section, having a cumulative subsurface thickness, in excess of 7000m is developed essentially into marine facies. Figure 10 is an isopach map of the Mesozoic sediments in the Project Area. From base to top the Mesozoic is differed into:

• The Triassic, • The Jurassic and • The Cretaceous

The Cretaceous is divided into the major units, titled the Lower Cretaceous, and the Upper Cretaceous. This comprises the Cenomanian, the Turonian, the Lower Senonian and the Upper Senonian. Table 2 gives more details about Mesozoic section.

The Cenozoic

The history of the Cenozoic in the Project Area and the adjacent areas witnessed three major dynamic events, which have a great impact on the sediments, with regards to their occurrence, distribution and mode of deposition. Such events include:

• the Late Cretaceous – Early Tertiary folding along the North African – Asian Margin. The folds, accounting for a great heterogeneity of the relief, were oriented in the NE-SW direction. Good examples having still their impression on the landscape are best represented by Abu Roash near Cairo City, Bahareya in the Western Desert of Egypt and Gebel Dalma in East Libya. In the sub-surface, similar features are detected in the northern portion of the Project Area as a result of the intensive petroleum exploratory work of the past 50 years.

Turonian L. Senomanian U. SenomanianLIBYA

Thickness 700m 500-3000 000 to 500 000 t0 200m 90 to 700mFacies continental/ fluviatile to marine continental to marine continental to marine continental to marine continental to marine Type Locality kufra regional regional regional regional regional

EGYPTThickness 000 to 50m 20 - 3000m 100 - 3000 000 to 500 000 to200m 70 to 700mFacies continental deltic to marine continental to marine continental to marine continental to marine continental to marineType Locality El Gilf regional regional Abu Roush regional regional

SUDANThicknessFacies continental continental continental continental continental continental continentalType Locality regional regional regional regional regional regional regional

CHADThickness 700mFacies continental continental continental to marine continental continental continental continentalType Locality regional regional regional regional regional regional regional

Location

Carateristics

Table 2 - Mesozoic : Lithostratigraphy and Paleogeography

CenomanianLower

Upper

STRATIGRAPHY

Triassic JurassicCRETACEOUS

50 to 725fluvitil to marineregional

90 to 725fluvitil to marineregional


• the process of the formation of the rifted areas during the Oligocene and presumably also the Miocene. The rift faults are detected in the eastern portion of the Project Area, mainly in the Red Sea Region and in the Upper Nile Region. Similar rift faults, oriented NW-SE are detected in the western portion of the Project Area mainly in Sirt Region. Active vulcanicity was associated with the rifting of such regions.

• the Messinian Crisis in Late Miocene times, when the level of the Mediterranean dropped to about 400 m below the present level. Major lagoonal deposits were formed as a result of desication processes in the Mediterranean depression. The drastic changes of the base level allowed many rivers to flow into the depression area, including in particular the Nile River in the eastern portion of the Project Area and El Sahabi River in the western portion. It allowed also for the development of steep northward gradients in the water levels of the already formed aquifer systems. The Mediterranean Depression acted as a major discharging area. An early Pleistocene event occurred in NE Africa, characterized by a variety of structural features, best represented by the swarm of E-W faults detected in the eastern portion of the Project Area. The pluvials of the Pleistocene and the sub-pluvials of the Holocene have also significant impressions on the landscape, as well as in the Nubian Sandstone Aquifer System. The sediments of the Cenozoic cover large tracts of the Project Area, south of Latitude 26°. These are represented by extensive and rather thin sand sheets and elongate dunes and also by scattered lacustrine deposits and calcareous tufa. To the north of that Latitude the Cenozoic is represented by thick marine deposits, dominated by carbonate facies, having a thickness in excess of 4000 m. In the Nile Delta Region the marine deposits are overlain by at least 1000m of fluviatile and fluviomarine deposits assigned to the Quaternary. Figure 11 is an isopach map of the Cenozoic in the Project Area. In the Project Area the sediments belonging to the lower portion of the Cenozoic, are unconformably underlain by the Upper Cretaceous sediments (or older sediments). The type and magnitude of unconformity differs in the regional tectonic provinces viz the Hinge Belt in the far northern portion, the Unstable Shelf Belt in the central portion and eventually the Stable Shelf Belt in the southern portion. In the Stable Shelf Belt, no major breaks in deposition are detected between the Upper Cretaceous and the Lower Cenozoic. In the Unstable Shelf Belt the relationship is governed by the paleo relief inherited from the Late Cretaceous. In the positive areas of the paleo relief great breaks are known as a result of the non-deposition of the total units of the Cenozoic. This relationship played a significant role in determing the hydrogeological characteristics of the Nubian Sandstone Aquifer System and the influence of the inland seawater intrusion. Reference can especially be made to major positive areas, which became manifested along the Mediterranean Region between the Nile Delta and Gebel El Akhdar, and which became morphologically developed in Post-Upper Cretaceous times. The details about the techtonical elements are indicated in figure 12.


The Cenozoic is differentiated into the following lithostratigraphic units (from base to top): • the Paleocene, • the Eocene, • the Oligocene, • the Miocene, • the Pliocene, • the Pleistocene, and the Holocene

The details about each unit is given in Table 3.

2.1.3.3The Geological Structure Regional Aspects

In the Project Area four successive structural belts are defined. From south to north these belts are:

• the cratonic belt in the south, • the stable shelf belt in the middle, • the unstable shelf belt in the north and • the hinge belt in the foreshore and offshore Mediterranean

The cratonic belt occupies much of the southern portion of the Project Area and including in particular Tibesti, Ennedi, Darfur, Dongla and Aswan. The stable shelf belt occupies the central portion and is wide spread in Libya and Egypt. Of particular interest about this belt is the recognition of broad basins or troughs, which were inherited in the cratonic surface. Of such basins reference is made to Kufra, Erdis and Dakhla. The unstable shelf belt is demonstrated in the northern portion, particularly in Egypt west of the Nile Delta and in Libya south of Gebel El Akhdar (almost all the Sarir area). The hinge belt has its impression along the Mediterranean coast (both inland and offshore) and is well represented in Gebel El Akhdar.

Local Aspects In view of the result, of both the deep boring and the geophysical surveys and also in reference to the published maps, the tectonical elements of the Project Area comprise a complex system of folds and faults. A good number of such elements became morphologically developed during the Late Cretaceous – Tertiary intervals and have still their impression on the landscape. Along the Mediterranean Region, many of such elements are reported in the subsurface and accounted for a severe discordance between the rock units forming both the Nubian and the Post Nubian Aquifer Systems. Of such techtonical elements, reference is especially made to the major flexures located to the north of the Qattara Depression, which could have accentuated for the sea–water intrusion phenomena into such aquifers.

2.1.4 Hydrogeology 2.1.4.1 General Outline In the Project Area, the strata of great hydrogeological interest are differentiated into two systems:

Carateristics Paleocene Eocene Oligocene Miocene Pliocene and HolocneLIBYA

Thickness 320-650 200-2000m 360-6000m 125-340 000-100Facies continental to marine continental to marine continental to marine continental + marine Mainly continentalType Locality S. Gebel Akhdar Gebel Akhdar Gebel Akhdar Ajdabia regional

EGYPTThickness 116-510 200-2000m 0-800 300-2000m 000-1000Facies continental to marine continental to marine marine continental to marine Mainly continentalType Locality N-Egypt N-Egypt N.E. Egypt Nile & Delta Delta

SUDANThicknessFacies very locally marine mainly continental continental continental continentalType Locality regional regional regional regional regional

CHADThicknessFacies continental continental continental continental continental continentalType Locality regional regional regional regional regional regional

TERTACYSTRATIGRAPHY

Location

Table 3 - Cenozoic : Lithostratigraphy and Paleogeography

+ 500mcontinental to marineN. Libya

500 - 3000mcontinental to marineN. Egypt

continentalregional


• The Nubian Aquifer System (NAS); underlying almost all the area of

Egypt, Eastern Libya, Northern Sudan and Northern Chad (Figures 13, 14 and 5). This consists of continental clastic sediments, mainly sandstone. It includes all the aquifers, the confining units and the aquicludes. This system overlies the Pre-Cambrian Basement Complex. The Strata forming the Nubian Aquifer System range in age from Cambrian to the Pre-Upper Cenomanian.

• The Post Nubian Aquifer System (PNAS); occurring to the north of the

26th parallel in the Western Desert of Egypt and North Eastern Libya. It is composed of marine sediments generally of clay, Marl and limestone, overlain by continental clastic sediments which exhibit, facies variation in the Northern parts of Egypt and Libya to pass laterally into carbonate facies. This succession ranges in age from Upper Cenomanian to Recent .

The two systems, are separated by low permeability layers (aquitard or confining beds), belonging to the Upper Cretaceous and to the lower Tertiary. These have no uniform stratigraphic definition. There may be some justification to limit them to the Upper Cenomanian as well as the Paleocene and part of the Eocene. Based on the stratigraphic setting of the study area and the paleogeographic events which took place since Post Turonian times (Late Cretaceous), the Nubian-Post Nubian contact displays local discordance which is represented by local open windows between the two sequences either due to the non-deposition, or erosion. This accounted for the reduction of the thickness of the Upper Cretaceous-Lower Tertiary deposits, and consequently for the establishment of a direct connection. This phenomenon is pronounced at the following locations:

• Tazerbo and Northwest Jabal Al Akhdar in Libya and • West Nile Delta – Sallum, Siwa-Qattara and Bahareya Oasis in Egypt.

2.1.4.2 The Nubian Aquifer System (NAS) 1 . Hydrogeological Units

The Pre-Upper Cenomanian geological succession, referred to in this study as the Nubian, comprises the oldest and the most extended reservoir of supreme hydrogeological interest in Northeast Africa. This succession, having a thickness ranging from less than 500 meters, to more than 5000 meters, shows a marked lateral change of facies, which plays a significant role in determining the hydraulic characteristics of the water bearing horizons. The succession can be differentiated into three distinct hydrogeological units (Table 4):

a) an upper unit, dominated by clastic facies, changing in the basin-wide ward direction into carbonate facies and is assigned to the Lower and Upper Cretaceous. This unit is extensive and is also highly productive.

b) a middle unit, dominated by sand facies with interbeds of carbonates beds. It is extensive and is also moderately to very low productive; it is assigned to Late Paleozoic and to the Early Mesozoic;


c) a lower unit, dominated by sand facies with interbeds of clays, assigned to

the Cambro-Ordovician, and is extensive and is also highly productive. For the present study the above hydrogeological units, constituting the multi layered aquifer system, have been assumed on a regional basis hydraulically connected and for all practical purposes to behave as a one layer aquifer system. This aquifer is under unconfined conditions south of 25th parallel and under confined conditions north of it (Figure 15)

2. The Aquifer Boundaries These comprise:

• the lateral boundaries of the aquifer (Figure 15); determined on the eastern side by the impervious Pre-Cambrian basement complex of the mountain ranges of the Red Sea and northwards the Suez Canal. The System eastern boundary is designed as a no-flow boundary. On the southern side it is determined by the outcrops of the Basement rocks of Southern Sudan (Kordfan and Darfur blocks) and Chad (Tibesti and Ennedi), which represents also a no-flow boundary. In the southeastern side, the Nile is represented at Nasser Lake and Dongola by a fixed head boundary. On the western side there is a groundwater divide extending from Tibesti mountains in the south and continuing northwards along the 19° Meridian. This boundary represents a no-flow boundary. The aquifer northern boundary coincides with the Mediterranean coastline, representing a fixed-head boundary.

• the base of the aquifer is taken at the surface of the Pre-Cambrian Basement complex. The Basement surface elevations fall regionally from Sea level in the southern part of the NAS to over 5000m b.s.l. along the northern boundary, as shown in Figure 7.

• the top of the aquifer is represented by the water table in the vast area south of Lat. 25º N., where the system is unconfined. Northwards, the aquifer is overlain by a low permeability confining bed of shales and carbonates, with its bottom forming the top of the NAS. Figure 15 show the bottom of the confining bed. It also shows that the confining bed is missing north of a lat. 30° between Marsa Matruh and Alexandria where the NAS and PNAS are in direct contact. 3 . The Aquifer Hydraulic Parameters

Data on the aquifer hydraulic parameters are only available in development project sites, leaving large areas of the aquifer with almost little or no data. Moreover, hydrogeological investigations in the study area are usually carried out very close to the surface, where most of the pump-tested wells were completed in the upper part of the aquifer (Mesozoic deposits), except for a few locations in East Oweinat in Egypt and Northern Sudan where the depth to the basement is relatively shallow and the drilled wells were fully penetrating. The system on the other hand, because of the relatively homogenous geology of the Nubian Aquifer System, where large geological units with relatively the same lithology are encountered, greater reaches


can be overcome by interpolation. Table 5 shows wide variations in the values of the aquifer parameter both regionally and even locally.

• the hydraulic conductivity of the lower part (Paleozoic) estimated as 10-5 to 10-6 m/s. For the upper part (Mesozoic) it varies from less than 4 x 10-6 to more than 10-3 m/s. The values for the aquitard are estimated as 10-7 m/s. for horizontal hydraulic conductivity and 10-10 to 10-11 m/s for the vertical hydraulic conductivity;

• the regional transmissivity (Figure 16) varies from 100 m2/d in the areas adjacent to the basement exposures to over 10,000 m2/d in the basinal area downdip where the thickness exceeds 3000m.

• the storativity for the unconfined portion varies from 7 x 10-5 in Kharga to 2.7 x 10-2 in Kufra. In this study an average value of 7% for the effective porosity and of 10-4 for the storage coefficient is taken.

4. Aquifer Potentiometry The data obtained from a good number of observation wells, assisted in the preparation of the initial potentiometric surface map (pre-development) Figure 16. This map gives indication to:

• the groundwater divide between Kufra and Chad basins, • the northwest flow of groundwater from Kufra to Tazerbo

and Sarir (Post Nubian), • steep northeast flow of groundwater from Kufra to Farafra, • a northeast flow from W. Howar area to East Oweinat area

and Kharga, • a complicated flow portion in the Nile Valley area to the

north of Qena Bend (faulted), • the lack of reliable information about the flow pattern at the

border area between Libya and Egypt to the south of Siwa-Jagboub area. 5. Groundwater Extraction Groundwater from the Nubian Aquifer System has been utilized since centuries in the Oases all over the area through springs and shallow wells. Intensive groundwater development for different purposes (Irrigation, mining, medical tourism and water supply) was initiated in 1960 in the Western Desert Oases of Kharga, Dakhla, Bahareya and Farafra while it started in 1990 in Siwa Oasis and East Oweinat areas, and lately in Darb El-Arbain area. In Libya, large-scale groundwater extraction from the Nubian Aquifer System started in 1970 in Kufra Production Project (KPP) and later in Kufra Settlement Project (KSP). No historical data regarding water extractions from the NAS was available for Sudan and Chad development areas. Figure 17 shows the locations of the extraction zones from the aquifer in Egypt, Libya and Sudan. The total extraction from the Nubian Aquifer System within the study area in 1998 is about 1376 mcm, of which 683 mcm in Egypt, 286 mcm in Libya and 407 mcm in Sudan. In Sudan, the figure includes extraction east of the study area i.e. east of The Nile River in Dongola area and may be even further south. Historical groundwater


extraction in the different development areas from the Nubian Aquifer System is indicated in Table 6.

Region CountryNumber of Pumping

Tests

Saturated Thickness

(m)

Average Screen

length (m)

Transmissivity (m2/sec)

Hydraulic Cond. (m/sec)

Storage Coefficient

(s)Wadi-Qena Egypt 6 650 250 9.905E-04 3.96x10-6Wadi ElLaquita Egypt 2 500 200 3.975E-03 1.98x10-5Bahareya Egypt 10 1880 196 8.700E-03 4.3x10-5 8.0x10-4Farafra Egypt 8 2600 221 1.200E-02 5.4x10-5Abu Munqar Egypt 3 2500 250 5.469E-02 2.18x10-4Dakhla Egypt 21 1850 181 1.100E-02 6.100E-05 6.35x10-4Kharga Egypt 59 1280 205 5.900E-03 2.900E-05 2.84x10-4East Oweinat Egypt 6 410 185 2.400E-02 1.300E-04Siwa Egypt 500 200 6.944E-02 3.42x10-4Aswan Egypt 1 200 100 2.778E-03 2.778x10-5Tazerbo Libya 5 2500 200 1.878E-02 9.4x10-5Kufra Libya 60 3000 134 8.749E-03 5.03x10-5 2.34x10-3West Selima Sudan 339 181 2.600E-02 1.436x10-4 1.43x10-4El Atrun Sudan 210 80 1.200E-02 1.500E-04Wadi Howar Sudan 374 39 1.700E-03 4.400E-05Um Hilal Sudan 139 80 2.600E-02 3.300E-04El Hashi Sudan 1.360E-02 2.390-04Dongola Area Sudan 29 161 9 1.064E-02 1.18x10-3

Source: GARPAD, 1981, Thoweih 1982, El Ramly 1983 and Kheir 1986

Table 5 - Average Hydraulic Parameters of The Nubian Aquifer System

Country Development Area 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979Egypt Kharga (Shallow) 37.33 37.06 35.07 35.08 30.84 27.17 26.46 24.74 23.49 23.49 22.28 22.04 21.05 20.33 20.01 19.45 18.25 17.51 15.79 16.51

Kharga & El Zayat (Deep) 13.62 20.51 44.73 66.67 65.01 66.90 61.22 65.62 64.10 62.98 65.83 64.55 68.95 66.34 68.35 66.79 67.67 68.97 69.77 73.79Kharga Total 50.95 57.57 79.80 101.75 95.85 94.07 87.68 90.36 87.99 86.47 88.11 86.59 90.00 86.67 88.36 86.24 85.92 86.48 85.56 90.30Dakhla (Shallow) 86.02 78.83 78.18 73.97 73.25 70.12 66.98 64.65 63.33 63.43 61.00 55.55 59.91 59.21 57.45 56.06 54.21 52.79 52.05 51.24Dakhla & W. Mawhub (Deep) 29.58 29.04 34.48 75.42 103.32 144.17 140.87 135.32 146.64 144.60 142.47 142.03 135.32 131.34 136.66 139.77 142.72 150.01 150.47 150.21Dakhla Total 115.60 107.87 112.66 149.39 176.57 214.29 207.85 199.97 209.97 208.03 203.47 197.58 195.23 190.55 194.11 195.83 196.93 202.80 202.52 201.45Farafra & Abu Minqar (Deep) 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10 1.10Bahareya (Shallow) 28.86 29.30 29.30 29.50 29.20 29.26 30.89 31.04 29.53 28.63 27.96 26.90 24.69 24.96 23.68 22.75 21.61 20.43 19.28 18.36Bahareya (Deep) 3.51 5.12 7.48 7.95 9.60 10.27 9.82 10.69 11.14 12.94 13.92 11.61 10.68 14.47 16.20 17.17 15.38Bahareya Total 28.86 29.30 29.30 33.01 34.31 36.74 38.84 40.64 39.80 38.45 38.65 38.04 37.63 38.88 35.29 33.43 36.08 36.63 36.45 33.74Siwa (Deep)East OweinatTotal Egypt 195.40 194.73 221.76 284.14 306.73 346.18 335.47 332.07 338.86 334.04 331.32 323.31 323.95 317.20 318.86 316.59 320.02 327.00 325.62 326.59

Libya Tazerbo OasisKufra Settlement 5.00 5.23 5.47 5.70 5.93 6.17 26.40 26.63 26.87 27.10Kufra Production 25.00 26.37 27.75 139.12 140.50 141.87 143.24 144.62 145.99 147.37Kufra Oasis* 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 4.40 6.80 9.20 11.60 14.00 16.40 18.80 21.20 23.60 26.00 28.40 30.80Total Libya 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 4.40 6.80 39.20 43.20 47.22 161.22 165.23 169.24 193.24 197.25 201.26 205.27

Sudan Sahara Nubian Basin Nile Nubian BasinTotal Sudan

197.40 196.73 223.76 286.14 308.73 348.18 337.47 334.07 343.26 340.84 370.52 366.51 371.17 478.42 484.09 485.83 513.26 524.25 526.88 531.86

*

Grand Total

The annual extraction was estimated according to the reported initial and present rates.

Table 6 - Groundwater Abstraction from the Nubian Aquifer System in Development Areas mcm/year)

Country Development Area 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 Grand TotalEgypt Kharga (Shallow) 16.26 14.21 12.48 11.02 9.76 6.00 5.58 5.16 4.74 4.32 3.90 3.70 3.50 3.30 3.10 2.90 2.55 2.20 1.85

Kharga & El Zayat (Deep) 77.00 83.18 88.66 93.58 98.05 107.90 110.58 113.26 115.94 118.62 121.30 122.26 123.22 124.18 125.14 126.10 122.60 119.10 115.60Kharga Total 93.26 97.39 101.14 104.60 107.81 113.90 116.16 118.42 120.68 122.94 125.20 125.96 126.72 127.48 128.24 129.00 125.15 121.30 117.45Dakhla(Shallow) 50.97 52.90 54.73 56.49 58.19 60.60 62.06 63.52 64.98 64.98 67.90 67.38 66.86 66.34 65.82 65.30 62.75 60.20 57.65Dakhla & W. Mawhub (Deep) 171.45 179.58 185.88 190.73 194.40 212.10 211.10 210.10 209.10 209.10 207.10 205.88 204.66 203.44 202.22 201.00 215.85 230.70 245.55Dakhla Total 222.42 232.48 240.61 247.22 252.59 272.70 273.16 273.62 274.08 274.08 275.00 273.26 271.52 269.78 268.04 266.30 278.60 290.90 303.20Farafra & Abu Minqar (Deep) 1.10 10.14 18.85 27.30 35.54 39.00 42.00 45.00 48.00 51.50 54.00 57.00 60.00 61.00 61.50 79.70 141.97 131.10 155.40Bahareya (Shallow) 17.70 18.19 19.03 20.17 21.53 20.10 22.40 24.70 27.00 29.30 31.60 31.56 31.52 31.48 31.44 31.40 28.50 25.60 25.00Bahareya (Deep) 16.22 17.14 17.73 18.42 19.08 20.10 20.64 21.17 21.72 22.26 22.80 23.26 23.72 24.18 24.64 25.10 28.05 31.00 31.69Bahareya Total 33.92 35.34 36.76 38.59 40.61 40.20 43.04 45.87 48.72 51.56 54.40 54.82 55.24 55.66 56.08 56.50 56.55 56.60 56.69Siwa (Deep) 20.00 20.00 20.00 20.00East Oweinat 10.50 10.50 10.50 10.50 10.50 10.50 20.50 30.50 30.50Total Egypt 350.70 375.35 397.36 417.71 436.55 465.80 474.36 482.91 491.42 501.44 519.10 521.54 523.98 524.42 524.36 562.00 642.77 650.40 683.24 16077.57

Libya Tazerbo Oasis 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55 1.55Kufra Settlement 27.34 27.57 27.80 28.04 28.27 28.50 28.74 28.97 29.20 29.44 29.67 29.90 30.14 30.37 30.61 30.84 31.07 31.91 32.15Kufra Production 148.74 150.11 151.49 152.86 154.24 155.61 156.98 158.36 159.73 161.11 162.48 163.85 165.23 166.60 167.98 169.35 170.72 175.49 176.85Kufra Oasis* 33.20 35.60 38.00 40.40 42.80 45.20 47.60 50.00 52.40 54.80 57.20 59.60 62.00 64.40 66.80 69.20 71.20 73.00 75.00Total Libya 209.28 213.28 217.29 221.30 225.31 229.31 233.32 237.33 242.88 246.90 250.90 254.90 258.92 262.92 266.94 270.58 274.54 281.95 285.55 6132.93

Sudan Sahara Nubian Basin 6.74Nile Nubian Basin 400.00Total Sudan 406.74 406.74

559.98 588.63 614.65 639.01 661.86 695.11 707.68 720.24 734.30 748.34 770.00 776.44 782.90 787.34 791.30 832.58 917.31 932.35 1375.53 22617.24

* The annual extraction was estimated according to the reported initial and present rates.

Table 6 - Groundwater Abstraction from the Nubian Aquifer System in Development Areas mcm/year)

Grand Total


6. Aquifer Response to Extraction Data of water level fluctuations in piezometers, (Egypt: 26 piezometers, Libya: 7 single piezometers and 42 dual piezometers) as a response to groundwater extraction from the NAS in the development areas were collected, reviewed and stored in the project database. Well hydrograps for some of the observation wells in two NAS development areas in Egypt and Libya, are presented and discussed in the following: Figure 18 and Figure 19 show the groundwater extraction in Kharga (Egypt) and the relevant changes in the water level respectively. They indicate that the groundwater extraction rate increased from 51.0 mcm/y in 1960 to 118 mcm/y in 1998. This created two groundwater depressions in the northern part of the Oasis with a maximum drop of water level of 60 m., while another depression occurs surrounding Bullaq-Garmashin zone with a maximum drop in water level of 35m. In 1960 the groundwater was extracted mainly from naturally flowing shallow wells and springs, while now 97% of the extracted water is pumped from deep wells. Figure 20 & Figure 21 show the groundwater extraction in Kufra (Libya) and the relevant changes in water level respectively. Less than 2 mcm/y was extracted in the sixties through shallow wells and springs. In 1973 the extraction has jumped to over 150 mcm and mainly from deep wells to grow progressively to over 284 mcm/y in 1998. This has lead to a decline in water level ranges between 10-20 m in Kufra production Project and to less than 5 m in Kufra Settlement Project during the period 1972-1998, creating a drawdown circle around the pumping centers of less than 25 km in radius. 7. Groundwater Quality Water quality in the unconfined part of the Nubian Aquifer System is good (TDS less than 1000 ppm) to excellent (TDS less than 500 ppm) all over the area. For the confined part of this system particularly in the area up to Lat. 30° in Egypt and Lat. 26° in Libya, the water quality changes laterally and vertically where the upper part of the aquifer system (Mesozoic) contains fresh water (TDS less than 2000 ppm), while the lower part of the aquifer system (Paleozoic) becomes saline very rapidly north of the Lat. 26° and west of the Long. 27° till it reaches the freshwater-salinewater interface where the whole aquifer becomes saturated with hypersaline water. The data obtained from Drill Stem Tests (DST) or calculated from SP logs for a good number of oil wells, in Libya and Egypt, tapping the upper most horizons of the Nubian Aquifer System, shows the groundwater chloride salinities (Figure 22). The occurrence of such saline water-freshwater Interface was attributed (El-Bishlawy, 1970) to the Post Cenomanian tectonic movements that initiated permeability barriers and prevented further northward freshwater flushing of the saline formation water. Part of the highly saline water can also be explained by sea water intrusion induced by the deep topographic depressions (below sea level) along the Lat. 30° and by the missing aquitard in the northern part of Egypt (between Marsa Matrouh and Alexandria) which may have contributed to the salinisation of the Nubian Aquifer. However an important part of saline water in the Nubian and the deep Post Nubian

Figure (19) is in the next page

Figure (18) - Water Production Histogram of Kharga Oasis

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60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98Year

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Figure (20) Water Production Histogram of Kufra Projects Area

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Aquifer system north of the Lat. 26° N in Libya is likely due to the presence of evaporates in the matrix of the water bearing formations. 2.1.4.3 The Post Nubian Aquifer System (PNAS) 1. Hydrogeological Units The Post Nubian succession can be differentiated into four different lithostratigraphic units, which form the following hydrogeological units Table 7:

• a localized top unit belongs mainly to Quaternary and dominated by fluviatile sand, clay and near-shore deposits. Well developed in the Nile Valley, the Delta, the coastal zone and the inland depression with a maximum thickness of 1000 m in the Nile Delta. The unit is highly productive.

• a regional top unit dominated by marl or marly limestone, with interbeds of clay and sandstone. Widely extensive in the plateau between the Nile Delta and Gebel Al Akhdar. Assigned to Middle Miocene, moderately to low productive.

• a middle unit, assigned to Upper Eocene, Oligocene and Miocene, dominated by fluvial sand and clay with interbeds of shallow marine limestone. This unit is very highly productive, and is extensive in Libya and Egypt.

• a lower unit, assigned to the Upper Cretaceous and Lower Paleocene. This unit is extensive in Egypt and is restricted in Libya dominated by carbonate facies with interbeds of clay and evaporates (locally missed in the northern portion of the area, due to erosion and/or non-deposition). The unit is generally low or non-productive.

2. Extent and Boundaries of the Aquifer

The Post Nubian Aquifer System (PNAS) overlies the Nubian Succession north of the 26th parallel in the study area (Figure 23), and assigned to the Mesozoic-Cenozoic (Post Lower Cenomanian), having a cumulative thickness of the order of 5000 m. This group is regionally missed in the southern part of the study area (with the exception of its southeastern extension in Sin El-Kadab plateau west of Aswan), due to non-depositional conditions and is also locally missed in the northern part due to erosion. The PNAS is bounded by:

• In the south by the 26th parallel demarking the limit of the deposition, forming a no flow boundary.

• In the west by the 19 Meridian north of Tibesti, as a no-flow boundary. • In the east, the Red Sea basement mountains and the Suez Canal, which

represents a no-flow boundary. • In the north by the Mediterranean sea.

The vertical boundaries of the aquifer are represented by its base, which coincides with the top of the confining bed to the underlying Nubian aquifer (Figure 23), while the top of the aquifer is represented by its water table.

Table 7 - Lithostratigraphic Units of the Post Nubian Aquifer System

AGE

LITHOLOGY

THICKNESS (m)

REMARKS

A

Fluviatile sand and clay and near-shore deposits

00-1000

Developed in Nile Valley and Delta, coastal zone and inland depression.

B

Shallow marine marly limestone with interbeds of shale and sandstone

00-1300

Developed in north Qattara and Barata areas.

C

Fluvio-marine sand and clay changing to limestone facies with volcanics

00-1500

Developed in west Nile Delta and Sarir

M

ESO

ZOIC

- C

ENO

ZOIC

POST

LO

WE

R C

EN

OM

AN

IAN

(P

OST

NU

BIA

N)

D

Carbonate facies, with interbeds of shale, evaporates ….. etc

00-3000

Developed in the northern portion of project area, locally missed by erosion.


3. Hydraulic Parameters

Table 8 represents the results of the interpretation of the pumping tests conducted in those wells tapping different aquifers of the PNAS (48 wells in Sarir well field in Libya and 18 wells in the Western Desert of Egypt). It indicates that the Post Nubian Aquifer Hydraulic conductivity ranges between 3.6 x 10-5 m/s. in the area between West Delta and Qattara Depression, 6.4 x 10-5 m/s. in northwestern Western Desert and 3.1 x 10-4 m/s to 8 x 10-5 m/s in Sarir.

The aquifer transmissivity ranges between 1.6 x 10-2 m2/s. in Sarir area, 2.8 x 10-4 to 2 x 10-3 m2/s. for the moghra aquifer in West Delta – Qattara depression Zone and 6 x10-5 to 8 x10-4 m2/s. for the middle Miocene limestone aquifer in El-Diffa plateau. Figure (24) shows the Post Nubian aquifer transmissivity map.

4. Aquifer Potentiometry Based on the available data about depth to water of those wells tapping the PNAS and their site elevations, a potentiometric surface map was prepared (Figure 24). The map indicates that the aquifer attains a groundwater elevation of 150 m.a.s.l in the southwestern part of Sarir proje ct areas, and decreases northward to zero at the 30° parallel. The map also shows a radial distribution of the groundwater flow from the core of Jabal al Akhdar with 400 m.a.s.l and northward to the sea and southward to the area extending from Ajadabiya in the west to Al Jaghboub in the east with water level is below Sea level (10 m.b.s.l), where it is lost by evaporation in the Sabkhas. This groundwater depression also extends further east in the northern part of the Western Desert of Egypt between Siwa Oasis and the Qattara Depression, (40 m.b.s.l) which acts as a natural discharge area for the aquifer. In Northeastern Western Desert (Wadi El Fareigh) and the western desert fringes of the Nile Delta, the aquifer (lower Miocene Moghra aquifer) is reported to be hydraulically interconnected with Nile Delta Quaternary aquifer where it receives a considerable recharge and drains its groundwater into Wadi EL Natrun lakes (RIGW/IWACO, 1998). 5. Groundwater Extractions Figure 25 shows the groundwater extraction zones from the PNAS in Egypt and Libya, where considerable aquifer development projects and private activities exist. In Egypt, groundwater production from the PNAS is practiced in the Oases of EL Farafra and Siwa through springs and shallow wells (1400 springs and shallow wells) and in Wadi EL –Fareigh area located south of Wadi EL Natrun depression (about 95 wells) for irrigated agriculture, as well as in the oil fields located in the northern part of the Western Desert where it is used for drilling activities and for domestic supply after treatment. In Libya, the PNAS is intensively utilized in the projects of Sarir North (83 wells), Sarir South (168 wells) for irrigated agriculture and the Water transport scheme in Sarir West (126 wells) as well as in the Jalu / Ojla (33 wells), in Marada (12 wells) and Jabal Al Akhdar for irrigation and domestic use as well as in the oil fields where water is used for drilling activities, oil recovery, etc. Records of historical extraction from the PNAS are only available for El Farafra and Siwa Oasis in Egypt and Sarir, Jalu / Ojla development areas in Libya while a limited data is available for the rest of the Aquifer extraction zones in both countries. The historical groundwater production from the PNAS in the different development areas during the

Table 8 - Average Hydraulic Parameters of The Post Nubian Aquifer System

Region CountryNumber of

Pumping TestsSaturated

Thickness (m)

Average Screen length

(m)

Transmissivity (m2/sec)

Hydraulic Cond. (m/sec)

Storage Coefficient

West Sarir Libya 3 615 260

Pr1 Libya 720 9 7.5x10-2 2.88x10-4 2x10-2

Pr2 Libya 706 206 1.25x10-2 1.38x10-3 5x10-4

Pr3 Libya 130 1.27x10-2 6.16x10-5 3x10-2

North Sarir Libya 6 130 5.8x10-2 4.4x10-4 5x10-4

South Sarir Libya 39 (1.435x10-2) 1.1x10-4 5x10-4

Marada Libya

Shallow 2.3x10-3 2.3x10-3 0.1-0.44

Deep 1.3x10-4 1.3x10-4 5x10-4

Jalo/ Ojla Libya 1.731x10-2 1.73x10-2 2x10-2-2x10-2

Moghra Egypt 11 31 2.75x10-4 2.75x10-4

Moghra Egypt 3 26 2.1x10-3 2.1x10-3

Marmarica Egypt 3 35 8.0x10-4 8.0x10-4

Western Plateau Egypt 1 46 6.4x10-5 6.4x10-5


period 1976-1998, are given in the Table 9, which indicates a total of 911 mcm/year is extracted from the aquifer in 1998, and as well be detailed here below:

• In Egypt 346 million m3/y was extracted from this system mainly in El Farafra, Sewa and W. El Fareigh.

• In Libya a sum of 565 million m3 were extracted in 1998 mainly from Sarir, Jalo, Ojla, Marada, Tazerbo and Jabal Al Akhdar. 6. Aquifer Response to Extraction Based on the observed decline in water levels in the Sarir water production projects during the period 1975-1977 to 1998, a contour map showing the drop in the water levels for the same period, is prepared. Figure 26 indicates a decline of water level ranging between 5-8m. within the North Sarir project, 3-8 in the South Sarir project and from 1-4m in the well field of the Sarir Water Transport Scheme. The map also shows that the cones of depression are connected and form a unique large depression enclosed by the 1m. iso-decline contour line due to the effect of the three well fields. No reliable data are available for the other areas. 7. Groundwater Quality On qualitative basis, the groundwater of the PNAS shows a wide variation in chemical quality. In areas of intensive development as Sarir, Jalo, Sewa and W. El Fareigh the good quality of the water is endangered by the upconing and/or the lateral flow of saline water. There is lack of detailed information to make synthesis of the problem even on the regional level.

2.1.4.4 Groundwater Genesis In the modern literature (mainly Butzer-1964, Pachur et al – 1986, Thorweihe in Said – 1990, Shata, 1992…..etc) there are facts of significant importance, which have a direct bearing upon this subject. These include: the facts related to the evolution of the landscape since Late-Miocene times, the facts about the fluctuations of the climatic conditions in Pleistocene and Holocene times and, and eventually the facts regarding the results of the applications of isotope hydrology.

• Within this area, the discovery of Late-Miocene rivers was made, particularly in E Libya, S Egypt and N Sudan. The lowland portions of such rivers are occupied generally by extensive sand sheets. The level of such areas was lowered topographically, because this old river system was connected to the Mediterranean, via the Nile River as well as the Sahabi River. In S Libya, S Egypt and N. Sudan, the Nubian Sandstone sediments essentially underlie the surface area of such rivers. It is, therefore, expected that the paleo-river system in addition to the Nile, should have played a significant role in the recharging history of the Nubian Sandstone Aquifer System (for quantification purposes, special studies in the fields of quantitative geomorphology, paleography, sedimentology and subsurface geology are wanted).

Country Development Area 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979Egypt Farafra 0.90 0.90 0.93 0.91 0.91 0.90 0.88 0.88 0.87 0.87 0.85 0.85 0.84 0.84 0.83 0.83 0.82 0.82 0.81 0.81

Siwa 65.85 65.85 65.85 65.85 65.85 65.85 65.85 65.85 65.85 65.85 65.85 65.85 66.85 66.85 66.85 66.85 66.85 66.85 66.85 66.85

Wadi El Fareigh

Total Egypt* 66.75 66.75 66.78 66.76 66.76 66.75 66.73 66.73 66.72 66.72 66.70 66.70 67.69 67.69 67.68 67.68 67.67 67.67 67.66 67.66Libya Jalo 5.00 5.50 6.05 6.65 7.31 8.01 8.80 10.56 12.67 15.60 30.00 30.40 30.80 31.20 31.60 32.00 32.13 32.25 32.38 32.50

Marada Oasis 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 1.00 1.20 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15

North Sarir

South Sarir 14.04 35.51 57.20 74.23 99.00

West Sarir

Tazerbo Oasis 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.60 2.80 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00

Jabal Akhdar 20.00 22.05 23.10 24.30 25.47 26.74 28.10 29.41 32.40 35.60 39.20 43.20 53.97 67.46 84.33 105.40 131.00 160.00 172.00 176.00

Total Libya* 27.50 30.05 31.65 33.45 35.28 37.25 39.40 42.47 48.67 55.20 75.35 79.75 90.92 104.81 122.08 157.59 204.79 255.60 284.76 313.65

94.25 96.80 98.43 100.21 102.04 104.00 106.13 109.20 115.39 121.92 142.05 146.45 158.61 172.50 189.76 225.27 272.46 323.27 352.42 381.31

Table 9 - Groundwater Abstraction from the Post Nubian Aquifer System (mcm/y)

* Indicated total abstraction does not include water production from Oil wellfields as data is not available

Grand Total

Country Development Area 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 Grand Total

Egypt Farafra 0.83 0.83 0.82 0.81 0.80 0.80 0.79 0.77 0.76 0.74 0.73 0.72 0.71 0.70 0.69 0.68 0.68 0.67 0.67

Siwa 65.85 83.68 101.15 118.32 135.25 155.00 171.00 187.00 203.00 219.00 235.00 242.20 249.40 256.60 263.80 271.00 271.00 271.00 288.14

Wadi El Fareigh 12.00 25.00 37.00 50.00 57.20

Total Egypt* 66.68 84.51 101.97 119.13 136.05 155.80 171.79 187.77 203.76 219.74 235.73 242.92 250.11 257.30 276.49 296.68 308.68 321.67 346.01 5325.02Libya Jalo 33.80 35.00 36.40 37.86 39.37 40.95 42.58 44.29 46.06 47.90 49.00 50.00 52.50 55.13 57.88 60.78 63.81 67.00 70.00

Marada Oasis 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15 3.15

North Sarir 7.06 75.00 86.12 85.10 71.62 71.34 51.74 59.92 49.18 65.25 66.79 42.13 42.17 40.24 38.00 36.00 35.00 18.00 18.00

South Sarir 82.12 114.58 141.75 139.47 91.39 143.64 142.25 131.18 106.14 130.40 129.70 96.53 91.44 95.09 93.00 92.39 91.50 53.10 53.10

West Sarir 41.75 70.56 81.21 82.67 94.70 95.10

Tazerbo Oasis 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00

Jabal Akhdar 181.00 186.00 191.00 196.00 200.00 220.00 240.00 260.00 280.00 300.00 320.00 340.00 360.00 380.00 400.00 400.00 375.00 350.00 323.00

Total Libya* 310.13 416.73 461.42 464.58 408.53 482.08 482.72 501.54 487.53 549.70 571.64 534.81 552.26 618.36 665.59 676.53 654.13 588.95 565.35 12062.80

376.81 501.24 563.39 583.70 544.58 637.88 654.51 689.31 691.29 769.44 807.37 777.73 802.37 875.66 942.08 973.21 962.81 910.62 911.36 17387.82

Table 9 - Groundwater Abstraction from the Post Nubian Aquifer System (mcm/y)

* Indicated total abstraction does not include water production from Oil wellfields as data is not available

Grand Total


• The fluctuations of the climatic conditions during Pleistocene and Holocene

times included a number of rainy events. Such events together with the existing river systems contributed, essentially, to the recharge of both the Nubian and the Post- Nubian Aquifer Systems. Modern rain events as well as the seepage from the Nile proper and the High Dam Lake most likely contributed to the recent formation of groundwater but in a very limited scale.

2.1.4.5 Potential Groundwater Resources

In the approach to this subject differentiation, is made between:

• the storage capacity and • the recoverable amounts of water.

1. For the Nubian Aquifer System reference is made to Table 10 which shows the

calculated NAS storage capacity in both its unconfined and confined parts, in the four sharing countries: Egypt, Libya, Chad and Sudan. It indicates that the total volume of groundwater in storage in the unconfined part is about 259.3 x 1012 m3, while the total groundwater volume stored in the confined part is about 265 x 1012

m3, of which 151 x1012 m3 is hyper saline occurring north of salt water-fresh water interface (Figure 22) and the rest of 114 x1012 m3 is fresh groundwater. Therefore, it can be concluded that the total volume of fresh groundwater stored in the NAS is about 373 x1012 m3. Table 11 shows the results of estimating the volumes of exploitable groundwater from the NAS in Egypt, Libya, Chad and Sudan, which indicates that under the above constraints, a total of about 8.9 x1012 m3. can be recovered from the aquifer, representing 2.4% of the volume in storage. If the annual groundwater extraction of 1380 mcm/year presently extracted in the aquifer four sharing countries would be kept constant, the recoverable reserves would la st for a period of about 4860 years.

2. For the Post Nubian Aquifer System Table 12 shows calculated PNAS storage

Capacity and Groundwater recoverable volume. It indicates that the total volume of Groundwater in storage is 84.60 x 1012m3 and the Groundwater recoverable volume of 6.443 x 1012m3. If we limit the freshwater occurrence to the North by the depression marked by several sabkhas along the parallel 30° N. the recoverable volume of freshwater is about 5.57 x102 m3.

2.2 MATHEMATICAL MODELING

The model developed by the project is not supposed to provide a detailed prediction of the aquifer response to various water development scenarios, but it has been designed to predict the regional behaviour of the aquifer and the regional influence of water development scenarios in existing and future well fields. The results of the model – i.e. the drawdown calculated - within the well fields themselves should therefore be considered as an order of magnitude of the drawdown which will actually be observed in reality. However, the software has the capability to create a submesh in an area where more detailed information is available. This facility may be used in the future to develop sub-models in the development areas.

Table 10 - Storage Capacity of the Nubian Aquifer System*

Area (km2)Saturated Thickness

(m)

Volume of Fresh Water in Storage

(km3)

128793.001498.80 151023.26

Water * Volume in

Storage (km3)

Area (km2)

33877.70

372950.17

136549.56

47806.89

154716.02

Saturated Thickness

(m)

1458.00 102303.56 11239.79

1887.00 48606.48 102416.78

* based on average formation bulk porosity of 20%

Region

Aquifer Unconfined Part

Area (km2)Saturated Thickness

(m)

Water * Volume in

Storage (km3)

All Occurrence Part with Saline Water

Water * Volume in

Storage (km3)

Egypt 311861.87 838.50 52299.24 503813.93

350835.24Libya 350732.68 1786.40 125309.77 403356.88 1407.48 113543.35

__ __

__Chad 232977.00 1026.00 47806.89

Sudan 373102.44 454.00

__ 264566.61 __

__

Total __ __ 259293.60 __

33877.70 __ __

__

Aquifer Confined Part

Total Volume of Fresh Water in Storage (km3)

150910.04 113656.57

__ __ __ __ __

__

RemarksArea (km2)Maximum

Allowed W.L decline (m)

18.40

29.40

1630.84

Total

Libya 52521.64 200.00

Egypt 375020.93 200.00 7.50

427542.57

Confined Part

1.05 12.28

* Aquifer Storativity: 10-4 for the aquifer confined part and 7% for the unconfined part.

Grand Total 1696216.60 8889.27

100.001268674.03

8.55 100.00

87.72

Total

373102.44 100.00 2611.72Sudan

8880.72

Table 11 - Total Recoverable Fresh Groundwater Volumes from the Nubian Aquifer System

Region

Egypt

Libya 2455.13 27.60

2183.03 24.60

Recoverable * Groundwater Volume (km3)

Percentage

Chad

Unconfined Part

232977.04 100.00

350732.68 100.00

311861.87 100.00

Area Ground Water

Volume in Storage *

Km2 (km3)

Table 12 - Storage Capacity of The Post Nubian Aquifer System and Recoverable Volumes

426479.32

494039.44

920518.76

Recoverable Volume **

(km3)

100.00 2985.351143.00 48746.586

726.00 35867.263 100.00 3458.27

Region

Egypt

Libya

Saturated Thickness (m)

Max. allowed W.L. decline

(m)

** based on 100m maximum allowed water level decline and 7% effective porosity

6443.63920.00 84613.849Total

* based on average formation bulk porosity of 10%

Remarks


The only way to appreciate the reliability of a model is to compare calculated and observed drawdown resulting from a past water abstraction. This was not always possible for the Nubian Aquifer System, because of the lack of historical data on both water abstraction and piezometric fluctuations in many areas. In areas where data were not available for the calibration over a past period of time (Jaghbub, Siwa, Bahereya, Farafra) the representativeness of the model was only secured by the steady state calibration which is generally not sufficient to guarantee the reliability of the medium and long term predictions. Basically the model included two layers corresponding to a deep reservoir called “Nubian” comprising the Paleozoic and Mesozoic continental deposits older than the Upper Cenomanian and a more recent reservoir called “Post Nubian” including the Tertiary continental deposits in Libya and the tertiary carbonate rocks in Egypt. The two aquifer systems are separated by low permeability layers forming an aquitard which does not have a uniform stratigraphic definition. It was assumed that the aquifer system is not in equilibrium and that the present natural outflow is not due to present recharge but instead to the slow depletion of the groundwater reservoirs filled up during the pluvial periods of the late Quaternary. The model was then designed according to this hypothesis. The Post Nubian reservoir exists only in Egypt and Libya but it is definitely more important in Libya in term of development potential. It was assumed to be under unconfined conditions all over its domain. In Sarir and Jalu-Awjilah areas, the Libyan development programmes increasing the discharge from 9.70 m3/s (306 Mm3/yr) today to 36.28 m3/s (1145 Mm3/yr) in 2010 then keeping it constant until 2060, were simulated. In Siwa, , the present discharge in that area 8.37 m3/s (264 Mm3/yr) has not been increased. The model calculated an additional drawdown of some 20 m in Siwa area, similar to that calculated with the constant discharge everywhere, and of some 20 to 65 m in Sarir well fields.(Figure 27). The Pre-Upper Cenomanian deposits, (Nubian Aquifer System) called Nubian, extend over the four countries but is intensively exploited in Egypt and Libya only. South of the 26th parallel, the Nubian Aquifer System is under unconfined condition. As anticipated, the unconfined part of the Nubian aquifers includes the most important groundwater potential of the whole basins: the extension of the cones of depression resulting from the water abstraction in existing and planned well fields in that part of the Nubian domain is always limited and makes it possible to multiply the centres of extraction. North of the 26th parallel, on the contrary, where the Nubian is under confined condition, the aquifer response to water abstraction from the various oases (essentially New Valley and Siwa), makes up a unique large cone of depression, though deeper in correspondence to the abstraction zones. This behaviour of the Nubian aquifers, north of the 26th parallel made it necessary to limit the future groundwater abstraction in the simulated highest scenario (Simulation 11) much lower than proposed by the Egyptian authorities. In the case of Siwa in Egypt and the symmetric Jaghbub referred to the political border, from where the Libyan authorities are planning to develop a water transport system to the most eastern Libyan coast, the reciprocal interference between the two development areas is so strong that the planned abstraction had to be limited to 68 Mm3/yr from both areas, also in view of the slight reliability of the model in that area and of the risk of deterioration of the water quality.


The highest scenario simulated on the Nubian aquifers is summarized on table 13, also showing the additional drawdown from 2000 to 2060, voluntarily limited to 50-60 m in each development area. Figure 28 shows the spatial distribution of the drawdown 2000-2060 induced by the increased water extraction in Libya and Egypt.

Table 13 - Highest development scenario from the Nubian Aquifer System - Results of the model

Development zone Present

extraction in Mm3/yr

Planned future extraction in Mm3/yr

Additional drawdown from 2000 to 2060

LIBYA

Unconfined part of the Nubian (Kufra, Tazerbo)

200 1455 25-30 m

Confined part of the Nubian (Jaghbub)

0 68 30-40 m

EGYPT

Unconfined part of the Nubian (East Oweinat, Tushka)

0 1449 40-60 m

Confined/unconfined part of the Nubian (New Valley)

547 847 30 – 60 m

Confined part of the Nubian (Siwa)

20 68 30-40 m

SUDAN

0 0

CHAD

0 0

In Sudan and Chad, there was not a clearly defined development programme within the limits of the modelled area. However, it can be anticipated that any development similar to that planned in Kufra or East Oweinat (1500 to 1700 Mm3/yr) would result in a similar aquifer response with drawdown ranging from 25 to 50 m. Exchange between the countries The flow across the political boundaries was calculated at various periods of the simulation:

• For the Post Nubian, the flow from Libya to Egypt would be equal to 1.17 m3/s all over the simulated period (1960-2060)


• For the Nubian. No significant variation would occur in the flow across the Sudan - Egypt border if Egypt implements East Oweinat as planned in Simulation 11. An increase of the flow from Libya to Egypt would also be observed in relation to the piezometric depression created in Egypt by the additional development of the New Valley and Siwa. The following recommendations concerning the modelling activities can be formulated to the countries concerned, particularly Egypt and Libya where most of the water extraction takes place:

• Monitoring of the aquifers (extraction, water level and water quality), especially in and around the development areas, should continue, so as to regularly update and possibly improve the model. In this respect the proposed sites for regional monitoring network should be completed as soon as possible, particularly for Siwa, Bahereya and Farafra lacking of any monitoring network;

• Water quality modelling should be undertaken in order to forecast the

possible deterioration of the water quality related to water use. The following essential data should be compiled and/or collected in the field prior to start working out the model:

Ø Horizontal and vertical distribution of the total dissolved solids (TDS) of the

water in the aquifer itself as well as in the over- and under-laying sediments, Ø Data governing the mass transport (dispersivity, diffusivity…) determined

from specialized aquifer tests in the field, Ø Possibly, time controlled data related to water quality in the aquifer for the

calibration of the model.

• Since the model and the related calibration and simulation data have been transferred to the countries, other simulations should be performed by the countries themselves in order to test other development scenarios and also to get acquainted with the use of the software.

• The model capability of creating submesh to describe and analyse local situations more precisely should be tested, particularly in Siwa, Tushka and East Awaynat,

• A special monitoring network should be set up to observe and possibly minimize the expected interference across the political boundaries between Siwa and Jaghbub and between East Awaynat and Selima.

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