Ground-Water Resources 

of the Bengasi Area, 

Cyrenaica, United Kingdom 

of Libya

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1757-B

Prepared under the auspices of the United 

States Operations Mission to Libya, the 

United States Corps of Engineers, and the 

Government of Libya

BBQPERTY OF U.S.GW«r..GlCAL SURVEY 

JRENTON, NEW JEST.W
Ground-Water Resources 

of the Bengasi Area 

Cyrenaica, United Kingdom 

of Libya

By W. W. DOYEL and F. J. MAGUIRE

CONTRIBUTIONS TO THE HYDROLOGY OF AFRICA 

AND THE MEDITERRANEAN REGION

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1757-B

Prepared under the auspices of the United 

States Operations Mission to Libya, the 

United States Corps of Engineers, and the 

Government of Libya

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1964
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402
CONTENTS

Page

Abstract _ _______________-__--__-_______--__--_-__---_-------_--- Bl

Introduction______-______--__-_-____________--------_-----------__ 1

Location and extent of area-----_______----___--_-------------_- 1

Purpose and scope of investigation---______-_______--__-------__- 3

Acknowledgments __________________________-__--_-----_--_____ 3

Geography___________--_---___-_____---____------------_-___---_- 5

General features.._-_____-___________-_-_____--_-_---------_-_- 5

Topography and drainage_______________________--_-------.-_- 6

Climate.____________________.__----- - 6

Geology____________________-________________________-___----__-__ 8

Ground water____._____________-____-_-______-__-______-_--_--__ 10

Bengasi municipal supply_____________________________________ 12

Other water supplies___________________-______-_-_-___-_--____- 14

Test drilling....______._______._______.___________ 15

Conclusions. _ ____________-_-__---__________-__--_____------_-___-- 17

Selected references.________________________________________________ 18

ILLUSTRATIONS

Page 

FIGURE 1. Map of Mediterranean region showing location of area of

investigation._________________________________________ B2

2. Map showing location of wells, galleries, and springs in Bengasi

area, Cyrenaica, United Kingdom of Libya______________ 4

3. Map showing distribution of average annual rainfall, northern

Cyrenaica___________________________________________ 7

4. Geologic map of northwestern Cyrenaica, United Kingdom of

Libya. ___________________.._-____._____________ 9

TABLE

Page 

TABLE 1. Records of selected wells in the Bengasi area_______________ B19

in

CONTRIBUTIONS TO THE HYDROLOGY OF AFRICA AND THE 

MEDITERRANEAN REGION

GROUND-WATER RESOURCES OF THE BENGASI AREA, 

CYRENAICA, UNITED KINGDOM OF LIBYA

By W. W. DOTEL and F. J. MAOUIRE

ABSTRACT

The Bengasi area of Libya, in the northwestern part of the Province of 

Cyrenaica (Wilayat Barqah), is semiarid, and available ground-water supplies 

in the area are relatively small. Potable ground water from known sources is 

reserved for the present and future needs of the city, and no surface-water 

supplies are available in the area. This investigation to evaluate known, as 

well as potential, water supplies in the area was undertaken as part of a larger 

program of ground-water investigations in Libya under the auspices of the 

U. S. Operations Mission to Libya and the Government of Libya.

A ground-water reservoir underlies the Bengdsi area, in which the water 

occurs in solution channels, cavities, and other openings in Miocene limestone. 

The reservoir is recharged directly by rainfall on the area and by infiltration 

from ephemeral streams (wadis) rising in Al Jabal al Akhtfar to the east. In 

the Baninah and Al Fuwayhat areas the ground-water reservoir yields water 

of fair quality and in sufficient quantity for the current (1959) needs of the 

Bengasi city supply. The test-drilling program in the area south and southeast 

of Bengasi indicates that water in sufficient quantity for additional public supply probably can be obtained in some localities from wells. The water, however, is moderately to highly mineralized and would require treatment or demineralization before it could be used for additional public supply. Much of 

the water could be used directly for irrigation, but careful attention would have 

to be given to cultivation, drainage, and cropping practices. The hazard of saltwater encroachment also exists if large-scale withdrawals are undertaken in 

the coastal zones.

INTRODUCTION

LOCATION AND EXTENT OF AREA

The city of Bengasi* (Banghazi), Libya, is on the southern Mediterranean coast and on the eastern side of the Gulf of Sidra (Sirte), 

560 kilometers (airline distance) east of Tripoli (Tarabulas), Libya, 

and 800 kilometers west of Alexandria, Egypt (fig. 1).

1 Geographical names used in this report conform to the usage of the U.S. Board on 

Geographic Names (1958).

Bl
40'

38'

10° 12° 14° 16° 18° 20° 22° 24° 

SARDINIA

V N 

*"-/ Cagliari

36°-

34°-

32°-

30° -

AREA 

OF REPORT

Bengasi 

(BanghazI)

Province of Cyrenaic

(Wilayat Barqah)

Base from National Geographic Map of 

Central Europe and The Mediterranean

FIGURE 1. Map of Mediterranean area showing location of 
GROUND-WATER RESOURCES OF THE BENGASI AREA B3

The Bengasi area, as described in this report, consists of a part of 

the coastal plain that lies east and south of Bengasi within an arc 

whose radius is approximately 35 kilometers. The report area consists of approximately 300 square kilometers (fig. 2).

PURPOSE AND SCOPE OF INVESTIGATION

This investigation of the Bengasi area was undertaken to evaluate 

the ground-water resources of a part of the coastal plain in northwestern Cyrenaica (Wilayat Barqah). It was part of a larger program of ground-water investigations in Libya, which have been in 

progress since 1952, by geologists of the U.S. Geological Survey assigned to the U.S. Operations Mission to Libya. The investigation 

was carried out between September 1957 and June 1958 through the 

joint work of the following workers: W. W. Doyel, geologist of the 

U.S. Geological Survey; F. J. Maguire, engineer of the U.S. Army 

Corps of Engineers; and M. J. Bessuni of the Government of 

Cyrenaica. The work included geological reconnaissance, collection 

of hydrologic data on existing supplies and previous ground-water 

exploration, and a test-drilling program which was financed by the 

U.S. Army Corps of Engineers because of interest in the area as a 

possible site for a U.S. military establishment.

ACKNOWLEDGMENTS

The writers wish to express their appreciation for the advice and 

assistance given by various staff members of the U.S. Operation Mission to Libya (USOM/L) and of the U.S. Embassy, including the 

following: Marcus J. Gordon, Country Director, USOM/L; Charles 

A. Wright, Provincial Director for Cyrenaica, Libyan-American 

Joint Service; Edwin L. Smith, Principal Officer, U.S. Embassy, 

Bengasi; and Hey wood H. Stackhouse, Acting Principal Officer, U.S. 

Embassy, Bengasi. Acknowledgment is also made of the helpful 

assistance and support given by the Mudirs of the districts involved 

and by the following officials of the Cyrenaican Government: The 

Honorable Hussein Mazeg, Wali of Cyrenaica; Essayed Wanis 

Gaththafi, President of the Executive Council of Cyrenaica; Buseif 

Yaseen, Nazir of Interior; Mutawel Suleiman, former Nazir of Agriculture ; Omar Jouda, Nazir of Agriculture; and Saad Obeidi, former 

Mutasarrif of Bengasi. Mr. Harry Adam, Water-Supply Engineer, 

Nazarat of Public Works, gave valuable assistance by providing available information on the existing water supplies in the Bengasi area. 

Parts of the investigation relating to the U.S. Army Corps of Engineers 

were carried out under the direction of Lt. Col. Artha D. Williams, Jr., 

District Engineer, U.S. Army Engineer District, Middle East.
B4 HYDROLOGY OF AFRICA AND THE MEDITERRANEAN REGION

20*00'

Base from Army Map Service, 1958

0 27 

Well

EXPLANATION

Intermittent lake

Roads, all weather, 

loose or light surface

Road, fair or dry 

weather, loose surface

 . . -__- _____;

Cart track

Salt marsh

A/23 

Altitude in meters

Sand dunes

Small hills

O 

Sink holes

FIGURE 2. Map showing locations of wells, galleries, and springs in Bengdsi area, 

Cyrenaica, United Kingdom of Libya.
GROUND-WATER RESOURCES OF THE BENGASI AREA B5

GEOGRAPHY 

GENERAL FEATURES

Bengasi, which has a population of approximately 70,533 (1954), 

is the capital of the Province of Cyrenaica, the eastern province of 

the United Kingdom of Libya and, together with Tripoli, is also a 

cocapital of Libya. The city was almost completely destroyed during 

World War II, but it has since been rebuilt and is now (1959) expanding beyond the prewar limits as a result of increased governmental and commercial activity. The harbor facilities were destroyed 

during the war, and the one section that has been partly rebuilt is 

accessible only to ships of shallow draft. The depth of water in the 

harbor can vary by as much as 1.5 meters as a result of a combination 

of tides and strong northeasterly or southerly winds. A railroad, 

built during the Italian occupation, extends from Bengasi eastward 

to Al Marj (Barce), a distance of about 100 kilometers. Another 

railroad, also constructed by the Italians, extends from Bengasi southward to Suluq, a distance of about 25 kilometers. The paved coastal 

highway that extends along the northern coast of Africa passes 

through Bengasi. The only other paved road in the area connects 

Bengasi with the airport located at Banmah, 20 kilometers inland (fig. 

2). There are numerous unsurf aced roads and trails in the area, many 

of which become impassable to vehicular traffic after heavy r^ins. 

Direct airline flights are scheduled from Bengasi to Tripoli, Cairo, 

London, and Nairobi.

Besides Bengasi and Baninah, the report area contains scattered 

small villages and a sparse population belonging to the Auaghir tribe. 

Some of the people are nomadic, coming down from the plateau of Al 

Jabal al Akhclar (The Green Mountain) during the rainy season to 

plant grain and to pasture herds of sheep, goats, and camels in temporary grasslands. During the dry season most of the stock is either 

driven back into the Jabal, slaughtered, or sold.

A thick soil cover is present in the Al Qawarishah area, immediately 

south of Bengasi, and irrigation which utilizes shallow dug wells is 

practiced on a small scale. Cultivation by dry farming methods is 

carried on intermittently elsewhere in the report area, depending on 

the amount of rainfall and the thickness of the soil. When sufficient 

water is available, the soil, where tillable, is moderately productive. 

However, a considerable part of the coastal plain consists of rocky 

outcrops of limestone and is therefore unfit for cultivation. Barley 

is the principal crop in the area, and wheat is grown on a smaller scale. 

Groves of date palms are cultivated in the coastal dune areas, where 

small crops of grapes and melons are also produced.

712-589 64 2
B6 HYDROLOGY OP AFRICA AND THE MEDITERRANEAN REGION 

TOPOGRAPHY AND DRAINAGE

The Bengasi area includes a gently undulating plain rising from 

the Mediterranean coast inland to the foot of an escarpment that 

trends parallel to the coastline. The plain widens toward the south 

as the coastline and escarpment gradually diverge. The escarpment 

is generally considered to be a wave-cut cliff and to represent a postMiocene shoreline. The elevated plateau east of the escarpment is 

known as Al Jabal al Akhciar.

The plain, which probably was formed as a wave-cut terrace, rises 

gradually from sea level to an elevation of about 120 to 150 meters at 

the base of the scarp. A narrow beach and a wide dune belt border 

the sea. A succession of sea-level salt flats is present between the 

dunes and a low coastal bluff, which marks the edge of the main 

terrace.

The plain, or terrace, has been dissected slightly by numerous 

ephemeral stream channels (wadis) that rise in the Jabal and drain 

westward to the sea. During the rainy season the wadis flow, but 

commonly little or none of the runoff reaches the sea. The two principal wadis in the area are Wadi al Qattarah, known as Wadi al 

Wa'ayrah in its lower reaches, and the Wadi an Nagharah. The 

Wadi al Qattarah drains a large area in the Jabal and, after heavy 

rains, discharges water onto the flatlands in the vicinity of Bengasi. 

The*Wadi an Nagharah drains a smaller area in the Jabal, and discharges water over a flat area 30 kilometers southeast of Bengasi.

The plain in the Bengasi area is underlain mostly by limestone 

mantled in places by red clay, sand, and gravel deposits. Karst (solution) features are conspicuous in the area, and solution channels probably are present to some depth below sea level. Solution features are 

most evident north of the Bengasi-Bamnah road, where the surface 

of the plain is pitted with sinkholes. The underground river Lete, 

6.5 kilometers east of Bengasi, is marked by a chain of connected 

caverns formed by the solution of limestone. The roofs of these 

caverns have slumped, and the course of the river is now apparent 

from the air. Evidence of Karst topography decreases southward, 

and few sinkholes are present in the area south of the BengasiBamnah road.

CLIMATE

Rainfall is seasonal, occurring mostly in the winter months, and 

varies considerably from year to year in both quantity and intensity. 

The average annual rainfall at Bengasi is 273 millimeters and at 

Baninah 251 millimeters. The precipitation on Al Jabal al Akhclar 

is greater on the average than on the coastal plain (fig. 3), but it, too, 

is seasonal in distribution.
ft 1 A "

Marsa Susah

Tulmaythah 

Tukr8h

BENGASI

50-100 

100-150 

150-200 

200-250 

250-300 

300-400 

400-500

and above

ATUqaylah

After Marchetti, 1938

FIGURE 3. Map showing distribution of average annual rainfal
B8 HYDROLOGY OF AFRICA AND THE MEDITERRANEAN REGION

Prevailing winds are from the north-northwest through north. Hot 

south winds (ghiblis) occur infrequently, and are sometimes accompanied by sand and dust.

GEOLOGY

The coastal plain in the Bengasi area is underlain chiefly by stratified rocks belonging to the Helvetian Group of middle Miocene age 

(Desio, 1935) (fig. 4). The group consists largely of limestones, 

which range in character from soft and amorphous to medium hard 

and crystalline and which contain some thin interbedded clays and 

marls. Some fragmented and disintegrated limestone (partially cemented limestone "sand") was found in test wells. For example, in 

well 11, the deepest test well drilled during this investigation, sand 

of probable Miocene age was found at a depth of 231 meters. The 

limestones, which were apparently deposited under near-shore conditions, are continuous throughout the area. They have undergone 

solution following deposition, and now contain numerous solution 

channels and caverns.

Rocks of the Helvetian Group are also exposed in the escarpment 

forming the inland margin of the coastal plain and in Al Jabal 

Akh^ar, where they are in contact with the younger rocks of the 

Tortonian Group of middle Miocene age (fig. 4). No Tortonian rocks 

have been identified in the coastal plain.

Rocks of the Helvetian Group in the Bengasi 'area dip generally 

less than 1°, and no regional structures are apparent. However, several faults have been postulated. Marchetti (1938) described a fault 

at Al Fuwayhat that strikes northeastward. Faults also have been 

postulated by other geologists at 'Ayn Zayyanah and Lete and in an 

area extending along the coast for more than 100 kilometers from 

Bengasi to near Tulmaythah. According to Cotterell,2 resistivity 

work in the Bamnah area has indicated a north-south fault in the 

vicinity of the 100-meter contour. The writers noted no marked surface evidences of faulting in the Bengasi area, and beds exposed in 

the wadi channels and in the escarpment appear to be virtually continuous. Evidence of structural deformation in the older Tertiary 

rocks of the Jabal suggests that the formations underlying the Miocene rocks of the coastal plain are probably folded and faulted.

Quaternary deposits in the Bengasi area range in thickness from a 

few centimeters to several tens of meters. A thick clay in the subsurface in the Jardinah-Suluq area has been placed n the Quaternary 

by Marchetti (1938). Marchetti also placed in the Quaternary the 

shelly, sandy limestone used for building in the Bengasi area. The

3 Cotterell, A. P. I., and Son, 1949, Cyrenaica water resources: London, 4 pts. [Unpublished consulting report for British Military Government]
GROUND-WATER RESOURCES OF THE BENGASI AREA B9

AdVULdaj. snoaovxado
BIO HYDROLOGY OF AFRICA AND THE MEDITERRANEAN REGION

red clay that covers much of the surface in the Bengasi area is probably also of Quaternary age and may, in considerable part, be a residual from solution of the limestone.

Recent deposits found along the coast are mostly in the form of 

unconsolidated, semiconsolidated, and consolidated sand dunes. Recent deposits of sand, silt, and gravel are also present in the wadi 

channels.

GROUND WATER

Except for bodies of water in the coastal dunes and some locally 

perched water in the coastal plain, the principal ground-water reservoir in the Bengasi area occurs in solution cavities, joints, and bedding 

planes in the limestone that underlies the coastal plain as well as Al 

Jabal al Akh<Jar. The upper surface of the ground-water reservoir 

is marked by a water table that lies near sea level at the shore but that 

gradually rises to altitudes of 5 meters or more near the escarpment 

marking the inland edge of the coastal plain. Farther inland in the 

Jabal the water table is at still higher altitudes. The depth to the 

water in a well in the area depends on the difference in altitude between the land surface and the water table. This difference in the 

coastal plain ranges from a meter or two near the shore to 175 meters 

or more in deep wells near the escarpment. The greatest depth to 

water observed in the area was 172.1 meters in well 7.

The yield of wells in limestone generally depends on the number 

and size of water-filled openings below the water table and on the 

degree of interconnection of these openings in the zone of saturation. 

Thus, wells drilled only a few meters or few tens of meters apart may 

have considerable differences in individual yields. For example among 

10 test wells drilled by the U.S. Army Corps of Engineers, 3 wells 

(Nos. 3, 7, and 9) had yields of less than 0.4 liter per second, and 2 

wells (Nos. 1 and 10) produced yields of 11.3 and 12.6 liters per second, respectively.

The ground-water reservoir is sustained and recharged by infiltration from rainfall and also by runoff in wadis that rise on the Jabal 

and disgorge onto the coastal plain. Such recharge probably takes 

place chiefly during the winter months when most of the precipitation 

falls. Recharge probably does not occur during every year or after 

every storm, but only after relatively intense and prolonged rainfall.

Water in the ground-water reservoir moves down the slope of the 

water table from areas of higher hydrostatic head, as from the inland 

part of the coastal plain and Al Jabal al Akhcjar, toward points of 

natural discharge near the shoreline. Most of the movement noted 

occurs through the more permeable zones of the limestone, particularly where solution openings are well developed. Sinkholes are
GROUND-WATER RESOURCES OP THE BENGASI AREA Bll

relatively common in the northern part of the coastal plain in the 

Bengasi, Baninah, and Al Kuwayfiyah areas, but are not particularly 

common in the central and southern parts of the report area.

Discharge from the ground-water reservoir takes place naturally 

through springs, submarine outflow, and evapotranspiration in salt 

marshes near the shore and artificially by withdrawals from wells 

and galleries for municipal, domestic, stock, and irrigation purposes. 

Perennial springs and ground-water pools in sinkholes are common 

in the coastal zone between Bengasi and Al Kuwayfiyah. 'Ayn es 

Salmam, Rommel's Pool, 'Ayn Zayyanah, and Lete Grottoes are 

typical. Discharge of ground water by submarine outflow is also 

probably considerable. Evapotranspiration of ground water is active 

in all the salt marshes, which extend discontinuously along the coast. 

The largest artificial withdrawals of ground water from wells and galleries in the area are for the Bengasi municipal supply, which is currently (1959) about 4,545 cubic meters per day. Small-scale withdrawals for irrigation, domestic and stock use also are made from 

dug wells scattered over the coastal plain.

Virtually all the ground water in the coastal plain at depths more 

than 10 meters below the water table is moderately to highly mineralized, containing in most places from 900 to 6,000 ppm (parts per 

million) of total dissolved solids. This condition may be due to several 

factors. First, the Miocene rocks were deposited in salt water and 

have undoubtedly been filled with salt water from time to time since 

their deposition. As a result, they may contain residual salt both in 

the limestone and in the associated clays. Because of insufficient 

circulation of fresh water through the rocks, the residual salt may not 

have been flushed out completely. Second, wind-blown salt spray and 

salt accumulated in the soil by evapotranspiration may contribute salt 

to recharging fresh water in some areas. Third, the ground-water 

reservoir in the coastal plain receives inflow of ground water from Al 

Jabal al Akhcjar that already contains a considerable content of dissolved solids. In most places, only the very shallow ground water 

that is, a skim a few meters thick below the water table is relatively 

fresh and low in dissolved solids. For example, in shallow well 26 at 

a depth of 64.5 meters the water contains a total of about 360 ppm of 

dissolved solids, whereas in well 1 in the same vicinity water at 73.5 

meters contains a total of 3,500 ppm of solids. In other shallow wells 

the dissolved-solids content is low. For example in wells 19,21 and 27, 

the water contains a total of only 580, 300, and 250 ppm, respectively, 

of dissolved solids. Elsewhere, both the shallow and the deep water 

is moderately to highly mineralized.
B12 HYDROLOGY OF AFRICA AND THE MEDITERRANEAN REGION

In the coastal zone of the Bengasi area, the nominally fresh water 

in the ground-water reservoir is inferred to be in contact with salty 

water along an interface, or zone of diffusion. The relationship between the fresh water and the salty water is probably similar to that 

expressed by the Ghyben-Herzberg principle (Brown, 1925, p. 16). 

This principle states that the approximate depth to which fresh water 

extends below sea level is determined by the head of the fresh water 

above sea level and by the difference in specific gravities of fresh and 

salty waters on opposite sides of the interface. Under conditions of 

static equilibrium, 1 meter of fresh-water head above sea level will 

balance about 40 meters of fresh water below sea level. Thus, a small 

change in fresh-water head above sea level may result in a large change 

in the amount of fresh water available below sea level. For this reason 

a ground-water supply in a coastal zone is exposed to the potential 

danger of salt-water contamination. Therefore, it is important to 

know the altitude above sea level of water levels in wells in the area, 

and a system of water-level measurements and quality control is 

essential.

BENGASI MUNICIPAL SUPPLY

Prior to World War II the water supply for Bengasi was derived 

from two sources: a system of galleries and wells at Al Fuwayhat, at 

the southern edge of the city, and a collecting gallery at Al Manastir, 

on the coast 5 kilometers northeast from the city. The combined 

sources yielded less than 4,540 cubic meters a day, and the water contained approximately 610 ppm of chloride. This supply was inadequate, and in an attempt to locate additional sources, the Italian 

Administration put down numerous test borings in the vicinity of 

Bengasi. The results, which were tabulated by Komano (1933) and 

commented on by Marchetti (1938), proved that a zone of saturation 

is present. Furthermore, the results indicated that the water table 

is slightly above sea level and that properly constructed wells would 

produce moderate amounts of usable water.

Al Fuwayhat waterworks consisted of a series of shallow collecting 

galleries, shallow wells, and five deeper wells ranging in depth from 

39.6 to 100.1 meters. During World War II, sections of the galleries 

were blocked and the pumping station and elevated storage tank 

destroyed.

Al Manastir waterworks consisted of two shallow infiltration galleries located in a sand dune area along the coast. The galleries 

yielded approximately 340 cubic meters a day of water containing an 

average of 1,100 ppm chloride.

After World War II, some sections of the collecting galleries at 

Al Fuwayhat were cleared, and two new wells were drilled in the
GROUND-WATER RESOURCES OF THE BENGASI AREA B13

galleries to a depth of approximately 88.3 meters. Later, four additional wells ranging in depth from 85.4 to 100.4 meters were drilled 

in the vicinity of the galleries by the British Military Administration. 

The water-collecting system now (1959) yields 4,200 cubic meters a 

day of water averaging 549 ppm chloride. The water from all sources 

is pumped into a ground-storage reservoir of 4,545 cubic meters 

capacity. In addition, an elevated concrete water storage tank has 

been constructed and put into service.

In the years following World War II, exploration for additional 

ground-water supplies was undertaken in the Baninah area by the 

Public Works Department, which had begun exploration and had 

completed a test well approximately 3 kilometers north of the Baninah 

railway station. The firm of A. P. I. Cotterell and Son was contracted 

by the British Military Administration to do the actual exploration. 

Cotterell continued the test-drilling operations and carried out a geophysical survey of the area. Twenty-three test wells were drilled 

along a north-south trending line near the 100-meter contour. The 

locations of 21 of the wells are shown in figure 2. The wells range in 

depth from 79.2 meters in well 32 to 112.5 meters in well 34. Water 

levels range from 1.03 meters above sea level in well 31 to 4.87 meters 

above sea level in well 34. The range in water levels suggests that the 

water is moving northwestward.

Three of the wells had yields of 25.1 liters per second, the capacity 

of the test pump; 11 had yields ranging from a few tenths to nearly 

12.5 liters per second; and 9, the southernmost wells, had such low 

yields that they were considered dry. The three wells with the highest 

yields, Nbs. 30, 32 and 33, were finished and equipped, and the water 

is now pumped into a reservoir that was constructed at Baninah. A 

12-inch water main connects the reservoir with the Bengasi system. 

Water for the Bengasi supply is now (1959) being obtained entirely 

from the Baninah wells and Al Fuwayhat waterworks. Al Manastir 

galleries are no longer used.

Four test wells located between wells 15 and 21 were drilled by 

Cotterell, 13 kilometers southeast of Bengasi, within a few hundred 

meters of each other. The wells ranged from 88.1 to 106.8 meters in 

depth and produced yields of 5.0 to 6.9 liters per second. The chloride 

content of the water was 490 ppm. The yields were not considered 

sufficient to justify construction of a pipeline to either Al Fuwayhat 

or Baninah, and the wells were plugged and abandoned.

Detailed information on the exploration program is given in the 

report by A. P. I. Cotterell,3 which also contains recommendations for 

water supply development in Al Jabal al Akh^ar area. The explora-

* See footnote p. B8.
B14 HYDROLOGY OF AFRICA AND THE MEDITERRANEAN REGION

tion program demonstrated that substantial water supplies of good 

quality could be developed from wells in the Baninah area.

OTHEB, WATEB STTPPLIES

South of Bengasi are scattered small oases in which water for 

limited irrigation is obtained from shallow wells. The oases are 

generally found within 8 kilometers of the coast. Typical of the oases 

is the Al Qawarishah area, located about 10 kilometers south of Bengasi. Here many shallow wells ranging in depth from about 6 to 12 

meters were used to irrigate small garden areas. About 80 of the 

wells in the area, apparently the shallower wells, are reported to have 

gone dry since World War II. This evidence indicates that a general 

lowering of the water table has taken place. An open collecting 

trench south of well 18, in the same area was also used during the war 

to supply water to the former Italian airfields of Al Birkah II and Al 

Birkah III. The trench yielded 1,020 cubic meters of water a day, 

containing about 490 ppm chloride.

A number of scattered wells are in the coastal plain southeast of 

the Bengasi-Al Qawarishah area. The wells (Nos. 12 29) are shown 

in figure 2 and are described in table 1. The deepest of the wells, No. 

26, is approximately 23 kilometers southeast of Bengasi and is 65.3 

meters deep. Four of the wells (Nos. 17, 22, 24, and 26) are reported 

to have been dug by the Eomans. The total dissolved-solids content 

of water from the wells ranges from approximately 250 ppm in well 

27 to approximately 2,250 ppm in wells 17,18, and 24. All the wells 

are reported to have low yields, and several are reported to go dry in 

the summer.

A test hole (No. 35, table 1) was drilled by the Hydraulique Afrique 

Co. to a depth of 350 meters at the former site of the U.S. Aircraft 

Control and Warning station (Al Birkah II), 6 kilometers south of 

Bengasi. Water from the well contained 11,200 ppm dissolved solids 

and 5,170 ppm chloride; for this reason it was abandoned.

Approximately 6 kilometers east of Bengasi on the north side of the 

Bengdsi-Bamnah road are the Lete grottoes, consisting of a chain of 

underground caverns in limestone. Ground water collects in and 

moves through the interconnected caverns. A pumping test made in 

the cavern near the King's Palace obtained a sustained yield of 3,490 

cubic meters of water a day containing a chloride content of 1,040 ppm.

Much of the basic water supply in the area for domestic and stock 

use is obtained from cisterns, many of which were constructed in the 

limestone during Roman times. These cisterns are in or near watercourses and collect water from rainfall runoff.
GROUND-WATER RESOURCES OF THE BENGASI AREA B15

TEST DRILLING

During the period September 1957 to June 1958, the writers participated in a test-drilling program carried out in the coastal plain 

southeast of Bengasi (fig. 2). This program was undertaken because 

(1) little information was available on the occurrence or quality of 

the water in the area, (2) the U.S. Army Corps of Engineers was 

interested in the area as the possible site of a military establishment 

and financed the program, (3) the Cyrenaican Public Works Department, which could not guarantee an adequate water supply from the 

Bengasi city system for a military installation, requested that no 

ground-water development be undertaken within 16 kilometers of the 

Baninah well field, making it necessary to seek new sources.

Test-drilling was begun at Qabr 'Abd Allah near well 26, which 

yields water of good quality. Wells, 1, 2, 3, 10, and 11 were drilled 

with a percussion drilling machine belonging to the Libyan-American 

Joint Service. Wells 4, 5, 6, 7, 8, and 9 were put down with a percussion drilling machine belonging to the Cyrenaican Drilling Co.

All the test wells, except 3,7, 9, and 11, were tested with a deep-well 

turbine pump. These four wells gave small yields in a bailing test, 

and no further tests were made. Water levels were not measured in 

any pumping wells because of the lack of proper equipment, but the 

discharge of the test pump was regulated so that a sustained yield 

could be maintained. The specific electrical conductance of the water 

from the test wells was measured with a Solubridge water tester, and 

the approximate amount of dissolved solids in the water was computed 

from the conductance.

Wells 1 and 10 yielded the largest quantities of water of any of the 

test wells. Well 1 was tested at 11.3 liters per second and well 10 at 

12.6 liters per second, the capacity of the pump. In both wells, however, the mineral content of the water increased shortly after pumping 

was started.

Water was found at a depth of 73.3 meters in well 1 and rose to 

61.5 meters below land surface. Drilling was continued to 155.5 

meters, but no additional water was found, and the hole was plugged 

back to 106.8 meters below the surface. Water taken from the well 

prior to pumping contained about 500 ppm of dissolved solids. After 

the well had been pumped 1% hours at 11.3 liters per second, the 

amount of dissolved solids had increased to about 3,500 ppm, where it 

remained for the duration of the test.

Water was found in well 10 at 10.7 meters and at 91.5 meters. The 

maximum sustained yield from the shallow zone was 0.31 liters per 

second, and the water contained a total of about 1,600 ppm dissolved 

solids. The quality of the water from the deeper zone stabilized at 

about 6,000 ppm dissolved solids shortly after the test pump was 

started. The well was plugged back to 56.4 meters below the surface;
B16 HYDROLOGY OF AFRICA AND THE MEDITERRANEAN REGION

and completed in the shallow zone. The present water supply for the 

village of Jardmah is obtained from the shallow zone.

Water was found in well 2 at 85.4 meters and rose in the hole to a 

depth of 70.1 meters below the surface. The well was completed at 

a depth of 119 meters. A yield of 2.5 liters per second was obtained, 

and the water contained about 3,200 ppm of dissolved solids after 4 

hours of pumping.

Well 4 was drilled to a depth of 90.8 meters, and water was found 

at 79.3 meters. The water rose in the well to 55.2 meters below the 

ground surface. The well yielded 1.9 liters per second of water containing 900 ppm dissolved solids.

Water was found in well 5 at 97.0 meters and rose to within 81.5 

meters of the surface. Drilling was continued to a depth of 110 

meters. The well yielded 1.3 liters per second of water containing 

approximately 2,600 ppm dissolved solids.

Well 6 was drilled to a depth of 57.9 meters. Water was found 

at 47.9 meters and rose in the well to a level 36.0 meters below land 

surface. The well yielded 1.0 liter per second of water containing 

approximately 900 ppm of dissolved solids. This well apparently 

penetrated a zone of perched water.

Water was found in test well 8 at 47.9 and at 76.2 meters, and 

the well was completed at a depth of 88.1 meters. Water rose in the 

hole to within 39.6 meters of the land surface. The well yielded 

3.8 liters per second with 10.7 meters of drawdown, and the mineral 

content of the water increased from about 650 ppm of dissolved solids 

to 900 ppm after 4 hours of pumping.

Test wells 3, 7, 9, and 11 yielded 0.31 liters per second or less in 

a bailing test and were not tested further with a pump. Well 3 was 

drilled to a depth of 188.5 meters and water was found at 151 meters. 

The water, containing about 3,000 ppm dissolved solids, rose in the 

hole to a depth of 137.7 meters. Well 7 was drilled to a depth of 

189.1 meters. Water containing about 1,100 ppm dissolved solids 

was found at 178.2 meters and came up in the hole to within 172.1 

meters of the surface. Well 9 was drilled to a depth of 186.0 meters 

and reached water at a depth of 172.1 meters. Water rose to within 

170.0 meters of the surface and contained about 900 ppm of dissolved 

solids. Well 11 was drilled to a depth of 251 meters. Water containing about 3,000 ppm dissolved solids was found at 118.0 meters 

and rose to a depth of 93.0 meters. A second water-bearing zone was 

penetrated at 249.5 meters and yielded water containing about 4,000 

ppm dissolved solids. The water level remained at 249.5 meters.

The results of the test-drilling program show that water is generally present under slight artesian head in solution cavities and other 

openings in limestone throughout the explored area. The yield of
GROUND-WATER RESOURCES OF THE BENGASI AREA B17

each well was found to be dependent on the size and number of openings penetrated in drilling. Only wells 1 and 10 penetrated sizeable 

openings, and their yields were larger than those of any of the other 

test wells. When most of the test wells were pumped, the dissolvedsolids content in the water increased abruptly. This fact suggests 

that only a thin skim of comparatively fresh water overlies more 

highly mineralized water.

Small bodies of perched water are present in the explored area, as 

shown by wells 6 and 10. These bodies are probably sustained by 

local recharge and are isolated hydrologically from the principal 

ground-water reservoir. The quality of the perched water probably 

would not change as a result of pumping, but the bodies are probably small and substantial development would deplete them rapidly.

The behavior of wells 3,7, and 11 indicates that some type of physical discontinuity is present between them and the test wells to the 

west. Further investigation would be necessary to determine whether 

this behavior is due to a fault, a facies change, or some other geologic 

or hydrologic discontinuity.

CONCLUSIONS

A zone of saturation underlies the coastal plain of the Bengasi 

area, where the water occurs in solution cavities and other openings 

in limestone. The ground-water reservoir is recharged by infiltration from rainfall on the area, and from ephemeral streams (wadis) 

while in flood. Some recharge also takes place by lateral inflow of 

water from the Miocene and older rocks in Al Jabal al Akh<Jar.

The results of the test drilling and other earlier exploratory work 

show that the quantity of water necessary for irrigation or for public 

supply can be obtained readily. However, in the part of the area 

that is not reserved for the Bengasi public supply, the water is too 

highly mineralized for public-supply use without expensive treatment. The water located by test drilling could be used for irrigation, provided application of the water to the soil and drainage 

conditions are closely controlled.

Ground water in the area southeast T>f Bengasi could also be used 

for moderately large municipal requirements, provided one of the 

water demineralization processes that are now in pilot-development 

stage becomes economically feasible. When such demineralization 

becomes feasible, it will be necessary to obtain more quantitative data 

regarding the extent of the ground-water reservoir and the amount 

of recharge to it. Additional exploratory drilling in the area is not 

justified until such time as the data are needed.

The Miocene limestone probably contains a continuous groundwater reservoir throughout the coastal plain of the Bengasi area.
B18 HYDROLOGY OF AFRICA AND THE MEDITERRANEAN REGION

Considerable amounts of water of better quality than that found in 

the area explored by the test drilling program can be obtained from 

wells in the Bamnah area because of the presence of larger and more 

continuous openings in the limestone, as indicated by surface evidence 

and possibly because of a higher rate of recharge. The water flowing 

from 'Ayn Zayyanah and the other springs east and northeast of 

Bengasi represents discharge from the ground-water reservoir, probably from the Banmah area.

The water-bearing limestone extends westward under the Mediterranean Sea, where it contains salt water. Increased withdrawals in 

the Banmah area or large-scale withdrawls elsewhere in the Bengasi 

area could result in the movement of salty water toward the area of 

heavy withdrawals, ultimately resulting in salt-water contamination. 

Additional investigation and exploration should be carried out to 

determine the long-term potential yield from the ground-water reservoir in the Banlnah area; that is, the amount of water that could be 

withdrawn without either depleting the reservoir or causing the 

encroachment of salty water.

No perennial surface-water supplies are available in the Bengasi 

area, although water flows in the wadis for short periods after heavy 

rains. The only other surface-water supplies are those that collect 

annually in cisterns excavated in the limestone.

SELECTED REFERENCES

Brichant, M. Andre L., 1952, A broad outline of the geology and mineral possibilities in Libya: U.N. Mission to Libya mimeo rept.

Brown, J. S., 1925, A study of coastal ground water with special reference to 

Connecticut: U.S. Geol. Survey Water-Supply Paper 537,101 p., 7 pis., 20 figs.

Department of Interior, Office of Geography, 1958, Libya: Washington, Gazetteer no. 41, U.S. Govt. Printing Office.

Desio, A., 1935, Studi geol, sulla Cirenaica, sul deserto Libico, sulla Tripolitania 

e sulla Fezzan oriental!: Rome, Miss. Sci. del la R. Ace. d'ltalia a Cufra, 

v. 1,464 p.

 1989, Studi morfologici sulla Libia oriental!: Rome, Miss. Sci. del la 

R. Ace. d'ltalia a Cufra, v. 2,216 p.

Gregory, J. W., 1911, The geology of Cyrenaica: Quart. Jour. Geol. Soc. [London], v. 47, no. 268, p. 572-615.

Hey, R W., 1956, The geomorphology and tectonics of the Jabal Akh^Lar 

(Cyrenaica) : Geol. Mag., no. i, p. 1-14.

Marchetti, M., 1938, Idrologia Cirenaica: Florence, Italian Col. Agri. Inst, 

245 p.

Romano, M., 1933, Cyrenaica Nuova : Bengasi.

Sanford, K. S., 1940, Libyan frontiers: Geog. Jour. [London], v. 96, no. 6, 

p. 377-388.

United Nations Food and Agriculture Organization, 1952, Report to the Government of Libya on Agriculture: Rome, Rpt. 1.
GROUND-WATER RESOURCES OF THE BENGASI AREA B19

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