UNITED STATES

DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY

PROPOSED ARTIFICIAL RECHARGE STUDIES IN NORTHERN QATAR 

By Joel 0. Kimrey

OPEN-FILE REPORT 85-343

Prepared in cooperation with the 

DEPARTMENT OF AGRICULTURAL AND 

WATER RESEARCH, QATAR MINISTRY 

OF INDUSTRY AND AGRICULTURE

Orlando, Florida 

1985
UNITED STATES DEPARTMENT OF THE INTERIOR 

DONALD PAUL HODEL, Secretary

GEOLOGICAL SURVEY 

Dallas L. Peck, Director

For additional information 

write to:

Copies of this report can 

be purchased from:

Office of International Hydrology 

U.S. Geological Survey 

MS 470, National Center 

Reston, Virginia 22092

Open-File Services Section 

Western Distribution Branch 

U.S. Geological Survey 

Box 25425, Federal Center 

Denver, Colorado 80225 

(Telephone: (303)236-7674)
CONTENTS

Page

Abstract................................................................. 1

Introduction............................................................. 1

Background.......................................................... 1

Purpose and scope................................................... 2

Acknowledgments..................................................... 2

Geologic setting......................................................... 3

Dammam Formation.................................................... 3

Rus Formation....................................................... 4

Umm er Radhuma Formation............................................ 4

Hydrogeology............................................................. 5

Ground-water use......................................................... 8

Feasibility of artificial recharge....................................... 15

Recommended scope of additional studies.................................. 18

Hydrogeologic appraisal............................................. 18

Management appraisal................................................ 22

Conclusions and recommendations.......................................... 22

References cited......................................................... 24

Appendix................................................................. 25

Work plan for the hydrogeologic appraisal........................... 25

ILLUSTRATIONS 

Figures 1-5. Maps showing:

1. Location of Qatar and delineation of the Northern and

Southern Ground Water Provinces...................... 6

2. Ground-water levels, September 1971.................... 9

3. Dissolved solids concentrations in ground water,

September 1971....................................... 10

4. Ground-water levels, September 1982.................... 11

5. Dissolved solids concentrations in ground water,

September 1982....................................... 12

6. Graph showing pattern of withdrawals from the

Government well fields, 1964-80.......................... 14

III
PROPOSED ARTIFICIAL RECHARGE STUDIES IN NORTHERN QATAR

By Joel 0. Kimrey

ABSTRACT

The aquifer system in northern Qatar is comprised of a water-table 

aquifer in the Rus Formation which is separated by an aquitard from a partially confined aquifer in the top of the underlying Umm er Radhuma Formation. 

These two aquifers, composed of limestone and dolomite of Eocene and Paleocene 

age, contain a fragile lens of freshwater which is heavily exploited as a 

source of water for agricultural irrigation. Net withdrawals are greatly in 

excess of total recharge, and quality of ground water is declining.

Use of desalinated seawater for artificial recharge has been proposed for 

the area. Artificial recharge, on a large scale, could stabilize the decline 

in ground-water quality while allowing increased withdrawals for irrigation. 

The proposal appears technically feasible. Recharge should be by injection to 

the Umm er Radhuma aquifer, whose average transmissivity is about 2,000 meters 

squared per day (as compared to an average of about 200 meters squared per day 

for the Rus aquifer).

Implementation of artificial recharge should be preceded by a hydrogeologic appraisal. These studies should include test drilling, conventional 

aquifer tests, and recharge-recovery tests at four sites in northern Qatar.

INTRODUCTION

Fresh ground water is a very limited resource in Qatar (fig. 1), an arid 

peninsula in the southwest part of the Arabian Gulf. However, expanding agricultural activities, particularly in northern Qatar, are highly dependent upon 

this limited resource for irrigation.

Background

In 1971 the Government of Qatar with technical assistance of the FAO 

(Food and Agricultural Organization of the United Nations), began Phase I of a 

long-range multiphase program of joint investigations of water resources and 

agricultural development. During Phase II of this joint investigation, technical consulting advice on artificial recharge was requested through the USAID 

(Agency for International Development) and received from the U.S. Geological 

Survey (Vecchioli, 1976). Phase II, completed in 1977, was followed by a 

third phase known as the Water Resources and Agricultural Development Project. 

Data collected during Phase III allowed a more refined and complex concept of 

the aquifer system in northern Qatar. Final results of Phase III related to
hydrology were published as The Water Resources of Qatar and Their Development: 

Volumes I-III, Eccleston, Pike, and Harhash, 1981. In 1984, during implementation of the joint investigation's Phase III recommendations, the Government of 

Qatar again requested services of a hydrogeologist for advice in the area of 

artificial recharge.

Purpose and Scope

Both the 1976 and 1984 requests for technical advice were related to 

artifical recharge of aquifers in northern Qatar by injection of desalinated 

seawater. Specifically, the 1984 request was for assistance in developing 

plans for an investigation of (a) methodology for injection of the desalinated 

water, and (b) the optimal amounts of water that might be recharged in this 

manner. Subsequently, the author spent November 18 to December 16, 1984, at 

Doha, Qatar, gathering and assimilating information and assisting in preparation of long-range plans for augmentation of ground-water resources by means 

of artificial recharge. Most of this time was spent in review of existing 

technical reports and data related to hydrogeologic conditions, and in discussion and field reconnaissance with personnel of the Department of Agricultural 

and Water Research, Ministry of Industry and Agriculture, State of Qatar.

The purpose of this report is to present the author's recommendations for 

hydrogeologic aspects of artificial recharge experiments in northern Qatar; 

the Appendix contains a work plan for conducting the proposed hydrogeological 

appraisal. The necessary background material on hydrologic conditions in 

Qatar is largely from previous reports and from data files made available to 

the author.

Acknowledgments

The author wishes to thank Mr. Muhammad Al-Faihani, Director, Department 

of Agricultural and Water Research, Ministry of Industry and Agriculture for 

generously providing office space, logistic support, and the full assistance 

of his staff. Thanks are due to numerous members of the Hydrology Section, 

Department of Agriculture and Water Research, for their gracious and excellent 

assistance and support of the author's activities in both the office and field. 

Finally, especial appreciation is expressed to Mr. Ibrahim Harhash, Groundwater 

Specialist. Hydrology Section for his invaluable technical assistance and numerous kindnesses.
GEOLOGIC SETTING

o 

Qatar occupies an arid peninsula of some 11,600 km which extends northward

into the Arabian Gulf from the main land mass of Arabia. The peninsula is about 

180 km along its north-south axis, and the east-west width at its widest point 

is about 85 km. The surface of the peninsula is of low to moderate relief with 

the highest altitudes of about 100 m occurring in southern Qatar where mesa-type 

hills and large barchan sand dunes represent the maximum relief on an otherwise 

flat and eroded land surface.

The Qatar peninsula is an integral part of the Arabian peninsula and the 

geology of Qatar follows the detailed and well-defined stratigraphy of Saudi 

Arabia as presented by Powers and others (1966) (in Eccleston and others, 

1981). The Qatar peninsula is underlain by a series of gently dipping to 

flat-lying sediments that were deposited on gradually subsiding basement 

rocks. The major structure of the peninsula is a broad north-south trending 

anticlinal arch with gentle crest and steeper marginal dips; this arch plunges 

to the north and south from a broad domal apex near the center of Qatar. 

Geologic structure along the west coast is complicated by the more tightly 

folded Dukhan anticline and adjacent syncline whose axes trend north-northwest 

to north.

Deposits of Pliocene, Miocene, and Eocene age crop out over the peninsula 

and are overlain locally by Quaternary deposits. The oldest strata exposed 

are the limestones of the Rus Formation of early Eocene age, but the most 

widespread outcrops are the dolomites and crystalline chalky limestones in the 

upper part of the overlying Dammam Formation of middle Eocene age. The Umm 

er Radhuma Formation of Paleocene age, directly underlies the Rus Formation 

throughout Qatar, but is not exposed at the surface. Mesozoic rocks have been 

identified during exploratory oil drilling by stratigraphic correlation with 

geological units in Saudi Arabia (Eccleston and Harhash, 1982).

The occurrence of fresh ground water in Qatar is restricted to the rocks 

of Eocene and Paleocene age, which are described below in descending order.

Dammam Formation

This formation crops out over most of the Qatar peninsula. Five members 

are recognized with general lithologies described below in descending order:

The Abarug Member, composed of dolomitic limestone and marl; 

the Simsina Member, composed of chalky limestones, some chert 

and clay; the Dukhan Alveodina Limestone Member, composed of 

massive whitish limestone with abundant fossils and variable clay 

content; the Midra Shale Member, composed of yellow-brown to 

greenish attapulgite shale; and the Fhaihil Velates Limestone 

Member, composed of whitish, compact, crystalline fossiliferous 

limestone. Total thickness of the Damman Formation is about 50 m. 

The upper part tends to be well-fractured and contains vugs and 

solution cavities.
Rus Formation

The Rus Formation conformably underlies the Dammam Formation throughout 

Qatar, but crops out only in relatively small areas that are northwest of 

Doha, and on the Dukhan anticline in western Qatar.

The lithology of the Rus Formation consists of white to brown, chalky, 

dolomitic limestones; marls, clays, and shales; and gypsum and anhydrites. 

The beds of dolomitic limestone and evaporite tend to be massive, and the 

clayey beds tend to be thin and occur as intercalations. The occurrence of 

thick gypsum beds is mainly confined to southern Qatar, where they may comprise more than half the total thickness of the formation. In northern Qatar 

these evaporite beds are generally absent and the Rus is predominately composed of carbonate facies.

Thickness of the Rus ranges from less than 30 to more than 90 m. The 

greatest variations in thickness tend to occur in the area of the structural 

high in central Qatar. The formation contains abundant fractures, vugs, and 

solution channels, particularly in northern Qatar where the carbonate facies 

predominate.

Umm er Radhuma Formation

The Umm er Radhuma Formation conformably underlies the Rus Formation. 

Their contact is marked by an abrupt lithological change from the cream or 

nearly white chalky limestone of the Rus Formation above to the gray brown, 

dolomitic limestone of the Umm er Radhuma Formation below. The Umm er 

Radhuma Formation consists mainly of a thick sequence of white to gray to 

brownish vesicular dolomites, dolomitic limestones, and limestones. Some 

siliceous zones occur in form of chert and silicified limestone or dolomite. 

Argillaceous and gypsiferous material is believed to occur only to a minor 

extent and near the base of the formation in Qatar. Thickness of the Umm er 

Radhuma is considered more than 300 m over most of Qatar; data available for 

three water-exploratory boreholes indicate thickness to range from 270 to 

330 m. The formation is well fractured and contains numerous solution 

cavities.
HYDROGEOLOGY

Rainfall over Qatar is the primary source of available freshwater. 

"Total average rainfall over Qatar may vary from 10 to over 200 mm in any 

one year but falls from individual storm events sometimes as high as 180 mm 

in 4-5 days (1966) have occurred. The model average annual rainfall would 

appear to be of the order of 75 mm in northern Qatar and slightly less in 

southern Qatar" (Eccleston and others, 1981, p. 5/18).

Recharge from local rainfall is the sole replenishment to the natural 

freshwater resource. Most recharge results from infiltration of runoff that 

collects in surface depressions, commonly from rainfall events of more than 

10 mm.

Eccleston and others (1981, p. 10/22-10/30) describe ground water in 

Qatar as occurring in three aquifers: the Alat (Abarug Member in this report) 

aquifer; the Rus aquifer; and the Umm er Radhuma aquifer. The water table 

occurs in either the Dammam or Rus Formations over most of Qatar. Occurrence 

in the Dammam, however, is generally confined to the lower-lying coastal 

areas.

The Alat aquifer occurs only in southwest Qatar, and contains brackish 

water that is probably recharged to the west in the outcrop area of the Dammam 

Formation in Saudi Arabia. The Alat aquifer is not discussed further in this 

report.

The Rus aquifer and the Umm er Radhuma aquifer comprise a two-layer 

system that contains all of the fresh ground water available in Qatar. The 

aquifers occur in vertically adjacent geologic formations, but are hydraulically separated by intervening less permeable materials. The deeper Umm er 

Radhuma aquifer contains highly saline water at some depth throughout Qatar, 

salinity generally being lower in the top of the aquifer and increasing with 

depth.

Eccleston and others (1981) have divided the areal extent of this twolayer aquifer system into two broad hydrogeologic areas, the Northern and 

Southern Ground Water Provinces, as shown in figure 1. This concept of 

separate ground-water provinces is very important to understanding the mode 

of occurrence and quality of ground water throughout Qatar.

The Southern Ground Water Province, geologically, is characterized by the 

persistence of relatively thick evaporite beds in the Rus Formation (the 

"depositional sulphate facies" of Eccleston and others (1981) as noted on 

fig. 1). These relatively impermeable, though highly soluble, sulphate beds 

have persisted, in part, because of the presence of the Midra Shale Member in 

the overlying Dammam Formation. This overlying shale has retarded downward 

migration of recharge water and thus retarded dissolution of the evaporite 

beds in the Rus Formation to a large extent. The end result is that evaporite 

beds are still intact and dense, and the Rus Formation is unsaturated with 

ground water over some large areas. The overall permeability of the Rus
51° 30'

LOCATION OF MAP AREA

NORTHE N P.KOV

<5 ^'"ov (^

^LIHIT Of UP» t 0*MMAM/»U' 

^ ! FOUHATION l>KONf ORIirv

x^ * i I J S b U ,T\ HERN

\ P V O V I M C E

25° 00' -. 

24° 30' -

Figure 1. Location of Qatar and delineation of the Northern and Southern 

Ground Water Provinces (from Eccleston and Harhash, 1982).
Formation is thus low in the Southern Ground Water Province. Where percolating meteoric waters have been able to penetrate to the Rus, some dissolution 

of the evaporite beds has occurred; this results in saturation of the Rus 

Formation in those areas, and the ground water is calcium sulphate in type. 

The land surface depressions that form as a result of subsurface dissolution 

tend to be relatively steep sided and up to 20 m in depth. Any hydraulic 

connection between the Rus and the underlying Umm er Radhuma aquifer is 

probably restricted to these areas where the land surface is depressed and the 

Rus Formation is saturated with ground water. Even there, it is likely poor 

because of the general lack of ground-water circulation in the Southern 

Province.

In summary, the Southern Ground Water Province is characterized by low 

transmissivity and the discontinuity of saturated zones in the Rus Formation; 

calcium sulphate type ground water; and lack of areal hydraulic connection 

between the Rus and the Umm er Radhuma aquifers.

The Northern Ground Water Province (fig. 1) is characterized, 

geologically, by the predominance of carbonate facies in the Rus Formation, 

with only trace or residual amounts of interbedded gypsum. "The virtual 

absence of gypsum is considered to be the result of non-deposition over 

the broad structural high at the northern end of the Qatar pericline and, 

also, its removal by dissolution in circulating ground water derived from 

recent recharge which has permitted an enhanced access to gypsum beds aided 

by the significant absence of lower Dammam shales in the centre of the 

peninsula," (Eccleston and others, 1981, p. 2/2). Note that both areas where 

evaporites were not deposited (the "depositional carbonate facies") and 

areas where they were deposited, but later removed by dissolution (the 

"residual sulphate facies") are included in this definition of the Northern 

Ground Water Province and shown in figure 1. In either case there has been, 

and continues to be, relatively vigorous recharge of meteoric waters and 

circulation of ground water in the Rus Formation. This circulation of 

ground water has resulted in enhanced permeability of the Rus in northern 

Qatar. Extensive dissolution and subsequent adjustment of land surface has 

produced a terrane of contrast to that of the Southern Ground Water 

Province. According to Eccleston and others (1981, p. 2/2) "In northern 

Qatar the landscape is made up of an almost contiguous series of depressions 

with small interval catchments ranging in area from 0.25 to 45 km2 with 

irregular bodies of colluvial calcareous soils accumulated in the lower part 

or along major drainage courses. In general, the landscape is a deflated 

and subdued one where the watershed between depressions may sometimes be 

imperceptible. In southern, central, and western Qatar, however, the landscape is entirely different being dominated by low hills formed by outliers 

of the Neogene formations, barchan sand dunes and extensive areas of flat 

eroded limestone peneplain. Wherever depressions resulting from subsurface 

solution occur, however, these are invariably isolated, well defined, and 

with a crater-like appearance with the floor sometimes as much as 20 m below 

the general peneplain surface." Calcium-bicarbonate type ground water occurs 

in the Rus aquifer and in the top of the Umm er Radhuma aquifer in the 

Northern Ground Water Province. Occurrence of this relatively fresh
water as a lens in the upper part of the Umm er Radhuma aquifer indicates 

recharge from the Rus aquifer and thus an areal hydraulic connection between 

the two aquifers in the Northern Ground Water Province.

Figures 2 and 3 show, respectively, ground-water levels and dissolved 

solids concentrations in ground water throughout Qatar in September 1971. 

Data for that period, when aquifer stresses were less than at present, 

are presented to illustrate influence of the different hydrogeologic conditions of the Northern and Southern Ground Water Provinces on occurrence of 

ground water. Most wells for which data are shown in south Qatar penetrate 

only the Rus aquifer; many wells in the Northern Ground Water Province are 

open to both the Rus aquifer and the underlying Umm er Radhuma aquifer. 

The higher water levels and head gradients in south Qatar (fig. 2) are a 

reflection of the lower transmissivity of the Rus aquifer. The conditions of 

low recharge and poor ground-water circulation are reflected in the generally 

poor quality of ground water in south Qatar (fig. 3). By contrast the lower 

water levels and head gradients, and better quality of water in north Qatar 

are indicative of higher transmissivities, recharge and ground-water circulation in the Northern Ground Water Province.

Note, in figure 2, the extensive area in west central Qatar where groundwater levels are below sea level. This is a topographically low area, just 

east of the Dukhan anticline, that is associated with the very large inland 

sabkha (salt flats) area of Zgain al Dahth. "This approximately 100 km of 

salt flats at or just below sea level is believed to be an important area for 

the natural discharge of ground water by evaporation." (Eccleston and others, 

1981, p. 10/12). "An important embayment in the contour pattern stretches 

from the vegetive area of the sabkha near Dukhan eastward toward Umm al 

Marwaqi and, to a less marked degree, on to the south of Doha. This feature 

is considered to be a result of the enhancement of permeability in the Rus 

Formation in the area of active anhydrite solution in the border zone between 

the Northern and Southern Groundwater Provinces in the stage prior to the overall collapse which leads to the deflated landscape typical of the Northern 

Groundwater Province" (Eccleston and others, 1981, p. 10/14).

Figures 4 and 5, respectively, show ground-water levels and dissolved 

solids concentrations in ground water throughout Qatar in September 1982. 

These are included, for comparative purposes, to show some effects of 

increased aquifer stresses over the period between the 1971 and 1982 data. 

Note, for example, that the areas in northern Qatar that are enclosed by the 

3 m water-level contour and the 1,000 mg/L dissolved solids concentrations 

contour are smaller for the 1982 data than for the 1971 data.

GROUND-WATER USE

Prior to the early 1960's all municipal water supplies in Qatar were from 

ground water. Small supplies were from local wells but the city of Doha was 

supplied by pipeline from a number of well fields in east-central Qatar 

(Eccleston and others, 1981, p. 12/1). These Government well fields are in 

the south-central part of the Northern Ground Water Province and withdraw
51° 00' 51° 30

26° 00* -

25° 30' -

25P 00'

too- DEPTH IN METERS ABOVE 

OR BELOW SEA LEVEL. 

CONTOUR INTERVAL 

METER

Figure 2. Ground-water levels, September 1971 

(from Harhash, 1984).
51° 00' 51° 30'

26° OO1 -

25° 30* -

25° 00' =1

^ / / / > 

 f? / * *

j/ , *' iaud^iNii

Figure 3. Dissolved solids concentrations in ground water. 

September 1971 (from Harhash, 1984).

10
51° 00' 51° 30'

26° 00" -

25° 30' -

25° 00' -

DEPTH IN METERS ABOVE 

OR BELOW SEA LEVEL. 

CONTOUR INTERVAL 

METER

Figure 4. Ground-water levels, September 1982 

(from Harhash, 1984).

11
51° 00' 51° 30'

26° OO1 -

25° 30' -

26° 00' =__

-KX»- CONCENTRATION, IN MILLIGRAMS 

PER LITER. CONTOUR INTERVAL 

1000 M6/L

Figure 5. Dissolved solids concentrations in ground water, 

September 1982 (from Harhash, 1984).

12
water from the Rus Formation. Beginning in 1964 water from these well fields 

was used to augment increasing supplies of desalinated seawater. Use of these 

well fields reached a peak in 1975 and 1976, then began to be reduced with the 

aim of phasing them out and developing brackish ground water nearer to Doha 

for use in blending with the desalinated seawater. Figure 6 shows the pattern 

of withdrawals from the Government well fields from 1964 to 1980.

Agriculture in Qatar is based almost entirely upon irrigation from ground 

water. The total gross extraction of ground water for irrigation purposes 

throughput Qatar increased from about 44 x 10 m /yr in 1972, to about 

56 x 106 m3 /yr in 1976, to about 76 x 106 m3 /yr in 1980. Almost all of these 

withdrawals are in the Northern Ground Water Province, where it is estimated 

that about 20 percent of total water extracted for irrigation is returned to 

the aquifers by seepage (Eccleston and others, 1981, p. 12/4-12/7). Present 

(1984) estimates are that total gross extraction of eround water for agricultural purposes in northern Qatar is about 90 x 10 m /yr. As withdrawals for 

municipal supply remain at a low level, this is probably a reasonable estimate 

for total extraction of fresh ground water in northern Qatar.

Natural recharge to the aquifers in northern Qatar is estimated at 12 

percent of the annual rainfall. The mean annual recharge is estimated at 

27 x nr/yr (Eccleston and others, 1981, D. 6/6-6/9). Thus the present 

(1984) gross rate of extraction (90 x 10 m /yr) is more than three 

times the mean annual (natural) recharge. This comparison is useful in 

pointing out the severity of the overdraft on the limited freshwater 

resources of northern Qatar. Based on 1980 water use, Eccleston and others 

(1981, p. 2/7) estimated that quality of ground water was deteriorating at 

a rate of 5 percent per year, due to both lateral and vertical saltwater 

encroachment. Those estimates of rate of quality decline have not been 

revised to reflect 1984 conditions, but the total extractions increased 

almost 20 percent from 1980 to 1984.

Most wells used for irrigation in northern Qatar withdraw water from both 

the Rus and Umm er Radhuma aquifers. These wells are, typically, about 30 cm 

in diameter and 60-70 m in depth. They are constructed as open holes through 

the Rus Formation and into the upper part of the more highly transmissive Umm 

er Radhuma Formation, which is separated from the Rus aquifer by an aquitard. 

Because these are composite wells it is not possible to apportion the total 

extraction to the individual aquifers. However, the transmissivity of the Umm 

er Radhuma is considered to be an order of magnitude greater than that of the 

Rus, so the greater part of total extraction may be apportioned to the Umm er 

Radhuma. Proportionate draft is even greater from the Umm er Radhuma when 

considered on a net basis of extraction versus recharge. That is, the estimated 20 percent of total extraction that returns as irrigation recharge is to 

the Rus aquifer. Thus, it is possible for storage in the Rus to actually be 

increased as part of the process of extracting and using ground water for 

irrigation. In addition, the natural recharge to the dual aquifer system first 

occurs to the Rus aquifer.

13
1

6

5

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x 3

10

2

1

n

-

-

-

_

' " ' ' ' .::. : 

::..;;:::::

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v^SvS 111

1 1 1 1 1 1 1 1 1 1 1 1 1

" [' ''.' :' : .-.

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-

,-. : , .- ..;;..; 

' - ". - ' ''-' - - '

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Figure 6. Pattern of withdrawals from the Government 

well fields, 1964-80 (from Eccleston, Pike, and 

Harhash, 1981).

14
FEASIBILITY OF ARTIFICIAL RECHARGE

As discussed above, ground-water extractions for agriculture in northern 

Qatar are greatly in excess of natural recharge, and it is further estimated 

that the quality is deteriorating at a rate of 5 percent per year (Eccleston 

and others, 1981, p. 2/7). Continued extraction in excess of recharge will 

eventually result in depletion of the fresh ground-water resource to the point 

that the present level of irrigation will be impossible. Projected increases 

in extraction will, of course, expedite this process.

Thus, the only means to maintain even the present level of agriculture in 

northern Qatar is the availability of some additional source of freshwater for 

irrigation. In this regard, it has been proposed to use desalinated seawater 

to meet these demands for additional irrigation water.

The simplest scheme for use of desalinated seawater would be to make it 

directly available via pipeline from the desalination plant(s) to the points of 

necessary irrigation application. However this is the least practical scheme 

because volumes of available water from the desalination plant probably would 

not match those volumes needed for irrigation. Because need for irrigation 

water will vary widely (on seasonal, daily, and even hourly basis) a large 

storage element must be available in the distribution system because the source 

volume will likely be either fixed or, in any event, not adaptable to the wide 

fluctuations in irrigation demands. Storage of large volumes of water in the 

environment of northern Qatar would appear to best be done by injection into 

the Rus and Umm er Radhuma aquifers. These units are capable of accepting and 

storing large volumes of water by well-injection for recovery and use in irrigation. Vecchioli (1976), in considering this same issue, pointed out the 

benefits that could accrue from a properly designed and executed artificial 

recharge scheme, as follows:

1. Stabilization or retardation of deterioration in quality of fresh 

ground water now resulting from lateral encroachment of saline water 

from the Gulf and (or) vertical encroachment from deeper ground water.

2. Use of the freshwater aquifer as a storage reservoir to even out 

fluctuations in demand, seasonally and daily, by irrigation.

3. Use of the freshwater aquifer as a transmission system to distribute 

desalinated seawater from one or more plants to (possibly) numerous 

and dispersed small tracts of irrigable land where the needed water 

could be recovered through on-site wells.

4. Use of the freshwater aquifer as a standby reserve of potable water in 

event of massive failure of distillation equipment.

15
The advantages of artificial recharge as pointed out above are obvious and 

considerable. Based on the available information on hydrogeology and hydraulic 

properties of the aquifers in northern Qatar, artificial recharge of the aquifer(s) with desalinated seawater appears technically feasible and worthy of 

additional study.

Artificial recharge by use of injection wells in northern Qatar should be 

to the Umm er Radhuma aquifer which is separated from the overlying Rus aquifer 

by an aquitard. The Umm er Radhuma aquifer is a much better injection zone 

from a quantitative standpoint; its average transmissivity is considered an 

order of magnitude greater than that of the Rus aquifer (I. Harhash, oral 

commun., 1984). Also the majority of ground-water mining (continuing unreplaced depletion of storage) by agricultural extractions appears to be from the 

Umm er Radhuma, and it is thereby more vulnerable to saltwater encroachment 

than the Rus aquifer. According to Eccleston and others (1981, p. 2/7) "Thus, 

while the upper aquifer is in approximate balance between recharge, (including 

irrigation return), outflow, transfer to the lower aquifer and limited abstraction the lower aquifer exhibits a progressively increasing deficit and where 

the freshwater reserve is being irreversibly displaced laterally by saline 

water." The potential for saltwater encroachment to occur by upconing of 

mineralized water at depth also appears to be a valid concern related to mining 

of water from the Umm er Radhuma; this is yet another reason for emphasizing 

that the Umm er Radhuma aquifer should be considered as the primary potential 

injection zone.

The optimum location for artificial recharge is in the interior of 

northern Qatar; that is, generally within the area enclosed by the 3 m water 

level and 1,000 mg/L dissolved solids concentrations contours (figs. 2 and 3). 

This is the area where the largest reserves of freshwater now occur, and the 

area where agricultural extractions are presently occurring or moving toward. 

Concentration of artificial recharge within this area would have maximum 

effectiveness in maintaining (even possibly expanding) the freshwater reserves 

that now occur there. Another reason for concentrating recharge in inland 

areas is that land surface altitudes are higher; thus the unsaturated zone is 

thicker and there is less possibility of water logging the land by rise of the 

water table in response to artificial recharge. Though a significant rise in 

the water table (in the Rus Formation) is not anticipated in response to 

injection of recharge to the Umm er Radhuma aquifer, this potential factor 

should be considered. It is possible, for example, that the separating aquitard may not be so competent as now visualized.

The volume and rate of injection water that an aquifer will accept is 

dependent only upon the aquifer's capability to transmit and store water, if 

it is assumed that there are no attendant geochemical reactions that may 

change the aquifer's hydraulic characteristics. Thus, in simply planning for 

injection, a good knowledge of the aquifer's coefficients of storage and 

transmissivity (and, if applicable, its degree of hydraulic connection to

16
adjacent zones) is sufficient. These aquifer characteristics are usually best 

determined by a planned program of test drilling and aquifer testing. It is 

then advisable to conduct actual recharge tests (to verify the aquifer's 

acceptance capability) prior to finalization of operational plans for injection.

Artificial recharge also involves recovery of the injected water, and 

usually involves a repeating cycle of injection-recovery operations. Additionally, artificial recharge usually involves injection and recovery of a 

higher quality water than the residual water in the injection zone. That is, 

a volume of high quality water is injected to displace lower quality formation 

water; then, at some later time, the cycle is reversed and part of the injected water is withdrawn for use. Injections are generally made when recharge 

water is available to be stored; and recovery is made when there is a need for 

use of the stored water.

Injection of a fluid of low density (desalinated water) into an aquifer 

that contains water of higher density (formation water in the Umm er Radhuma 

aquifer) results in formation of a lens, or bubble, of the lower density 

fluid. The fluids of different density will tend to mix in a gradational zone 

at the outer limits of the lens, so that the total amount of freshwater 

injected cannot be recovered. If water is withdrawn from the storage lens 

until its quality declines to some arbitrary limit (such as 1,000 mg/L dissolved solids concentration), the ratio of volume recovered to volume injected 

is an index of the efficiency of the recharge-recovery operation. The ratio, 

expressed as a percentage, is known as the "recovery efficiency." This 

parameter, which must be determined experimentally, is the most useful and 

practical indicator of the feasibility of an artificial recharge operation.

In further study of feasibility of artificial recharge in northern Qatar, 

experiments to determine a range of values for recovery efficiency are recommended, in addition to the more standard test-drilling and aquifer-testing 

procedures.

Some extensive investigations have been made of injection, storage, and 

recovery of surplus freshwater in central and south Florida, southeastern 

United States. The hydrologic characteristics of the Umm er Radhuma aquifer 

are similar to those of the carbonate aquifers in Florida; therefore some 

useful conclusions can be drawn from previous studies (Merritt and others, 

1983) (Merritt, 1983). The conclusions which should apply to the proposed 

studies in northern Qatar include:

1. Physical processes which limit the recoverability of injected freshwater are hydrodynamic dispersion; buoyancy stratification; differences in directional permeability; and downgradient displacement by 

the local background flow system.

2. For a given volume of injected freshwater, the rate at which freshwater is injected (or recovered), does not appear to affect recovery 

efficiency. Generally, recovery efficiency will improve with 

increased volumes.

17
3. The length of time of storage does not effect recovery efficiency if 

(a) the regional gradient does not significantly move the stored 

freshwater, and (b) buoyancy stratification cannot occur under prevailing hydrogeologic conditions.

4. Partial penetration of the injection well does not appreciably affect 

recovery efficiency.

5. Recovery efficiency improves with repeated cycles, rapidly during 

initial cycles and then more slowly as a limit is approached.

6. Aquifers with water just saline enough to be unsuitable for consumptive use are optimum for freshwater injection and recovery, whereas 

very saline aquifers are least suitable.

7. Verification of the feasibility of cyclic injection, storage, and 

recovery of freshwater at specific sites can be determined only by 

performing actual tests. The amount of injected water that can be 

recovered before the withdrawn water becomes nonpotable is the prime 

indicator of the engineering success of the practice.

RECOMMENDED SCOPE OF ADDITIONAL STUDIES

Additional studies required prior to planning and implementation of the 

operational system for large-scale artificial recharge in northern Qatar are 

(1) a hydrogeologic appraisal, and (2) a total water-management study.

Hvdrogeologic Appraisal

A hydrogeologic appraisal should investigate and document the capability 

of the Umm er Radhuma aquifer to receive and store injected water and the 

degree of efficiency with which this water may be recovered for use. Results 

of this appraisal will indicate the best areas for injection of recharge 

water; optimum methodology for injection; and total volumes that it will be 

practical to inject, store, and retrieve.

The available hydrogeologic understanding of northern Qatar is an excellent base for beginning additional quantitative studies and experiments 

related directly to use of the aquifer for storage and recovery of desalinated 

water. This hydrogeologic appraisal should include test drilling, geophysical 

logging, aquifer testing, and recharge-recovery experiments at four sites in 

northern Qatar. These sites should be stratigically located in each of the 

four quadrants of the area that is generally enclosed by the 1,000 mg/L 

contour of the September 1982 map of dissolved solids concentrations. The 

following should be done at each of the four sites:

18
1. A test hole should be drilled to a depth where the formation water 

has dissolved solids content of at least 10,000 mg/L. During 

drilling, continuing observations should be made of changes in 

lithology, salinity, water levels, and water yield of the test borehole. The percussion method of drilling should be used because it 

lends best to continuing collection of these data during drilling.

2. Borehole geophysical logs should include, as a minimum, caliper; 

electrical resistivity and spontaneous potential; borehole fluid 

conductivity and velocity; and natural gamma.

3. The test borehole should be converted to use as an injection well for 

the upper part of the Umm er Radhuma aquifer by (a) grouting the 

bottom of the hole with cement to seal off to a depth where salinity 

does not exceed a maximum of 4,000-6,000 mg/L, and (b) sealing off 

the Rus aquifer by installing casing to the Rus-Umm er Radhuma 

Formations contact.

4. Four piezometers should be installed at each site three to moniter 

the Umm er Radhuma aquifer only, and one to monitor the Rus aquifer 

only.

5. Pumping tests of estimated 1-week duration should be made to determine the transmissivity and storage coefficients of the Umm er 

Radhuma aquifer, and to investigate the nature of hydraulic connection between the Rus and Umm er Radhuma aquifers.

6. A series of recharge-recovery cycle experiments should be made for an 

estimated total period of 90 days at each site. For planning purposes it is suggested that each cycle be about 2 weeks in length 

(about 1 week of injection followed by withdrawal until the appropriate level of dissolved solids content is reached). This would 

allow collecting data over a total of six complete recharge-recovery 

cycles at each site.

Some additional comments in regard to accomplishing the above work items 

are:

1. The source of injection water for the recharge experiments might, 

of necessity, have to be from wells in the Rus aquifer, because 

desalinated water may not be available at sites that are selected for 

the experiments. In this regard, some of the existing well fields in 

the Rus aquifer could be used as experimental sites; or new wells in 

the Rus aquifer might be drilled for sites that may be selected in 

other areas. In either event care should be taken that composite 

wells in the Rus and Umm er Radhuma aquifers are not present in 

enough proximity to interfere with hydraulic tests at the experimental sites.

19
It should be noted that geochemical reactions in the Umm er Radhuma 

aquifer may be different in response to injection of water from the 

Rus aquifer, than to injection of desalinated seawater. However, it 

is considered unlikely that these reactions would have any significant effect on the hydraulic characteristics of the Umm er 

Radhuma aquifer.

It is arbitrarily assumed that the contrast in dissolved solids 

concentration of the recharge water used and the residual water in 

the injection zone should not exceed about 2,000 mg/L. In most areas 

likely to be selected as experimental sites, dissolved solids concentration of ground water in the upper part of the Umm er Radhuma 

aquifer is likely to approach 2,000 mg/L and that in the Rus aquifer 

to be less than 1,000 mg/L. So the assumed range of contrast in 

dissolved solids concentration should prevail, whether the source of 

recharge water is the Rus aquifer or desalinated seawater. However, 

a minimum thickness of injection zone is suggested as 5-10 m, depending on concentration and vertical distribution of dissolved solids 

concentration in the upper part of the Umm er Radhuma aquifer. Hence, 

at some sites, it may be necessary to inject to a zone where the 

resident total solids are on the order of 4,000-6,000 mg/L (which is 

thus used as the limit in item 3 above).

Rates of injection for the recharge experiments may be dependent upon 

quantity of water available for injection, and the hydraulic characteristics of the injection zone. Thus, rates of injection cannot be 

selected until information on these two factors becomes available. 

Assuming availability of injection water, it is recommended that 

injection rates not cause more than 10 m of head buildup in the 

injection well. The maximum recommended injection rate (Ri) may thus 

be expressed in terms of the specific capacity (Cs) of the injection 

well as:

Ri = Ah.Cs _< 10. Cs

20
Successful completion of all work items above will require a 2-year period 

of investigation and the full-time assignments of two hydrogeologists (or 

ground-water hydrologists). Estimated costs for the hydrogeologic appraisal 

are:

1. Testhole Drilling;

(4 holes, 30 cm diameter) (200 m/hole) at 720,000 

QR. 900/meter

2. Geophysical Logging:

(4 holes) at QR. 8,000/hole 32,000

3. Converting Boreholes;

(a) Casing - (4 holes) (50 m/hole) at QR. 300/meter 60,000

(b) Grouting - (4 holes) (140 m/hole) at QR. 50/meter 28,000

4. Piezometers;

(4 holes, 15 cm diameter) (40 m/hole) at QR. 96,000 

600/meter

5. Piezometers;

(12 holes, 15 cm diameter) (60 m/hole) at QR. 432,000 

600/meter

6. Aquifer Tests:

(4 wells) (7 days/well) at QR. 4,500/day 126,000

7. Recharge-Recoverv Tests;

(4 wells) (90 days/well) at QR. 4,800/day 1,728,000

8. Project Hvdrologists:

(2) (24 months) at QR. 30,000/month 1,440,000 

Subtotal 4,662,000

Contingency allowance

(15 percent) 700,000

Total 5,362,000

21
Management Appraisal

6 o 

In 1980 total freshwater use in Qatar was about 107 x 10 m , of which

about 58 percent was the net fresh ground water used for irrigation and 41 

percent was desalinated seawater used for public water supply. Since 1964 the 

percentage of total freshwater used for domestic consumption has increased more 

rapidly than that used for agriculture, but both elements have experienced 

steady growth (Eccleston and others, 1981, table 12.4, p. 12/8). Other elements of 

total water use reported for 1980 were 3.3 x 10 m of brackish ground water 

used for blending, and 1.6 x 10 m of treated sewage effluent (renovated 

wastewater) for irrigation of trees and public landscape projects. Use of 

renovated wastewater is a relatively new and growing element in total water 

use.

Thus, total water use in Qatar has grown rapidly over the past 20 years, 

and promises to continue to grow and become more complex. Large scale artificial recharge by use of desalinated seawater, if implemented, will add another 

significant element. Hence, a management study is recommended concurrent with 

the hydrogeologic appraisal. Specifically, this management appraisal should:

1. Consider all the factors related to planning and implementation of 

artificial recharge in northern Qatar. This appraisal should integrate results of the hydrogeologic appraisal with other pertinent 

engineering factors to include availability of water for recharge; 

distribution of water from the desalination plant(s) to irrigation 

areas; and various combinations of aquifer storage-distribution 

through artificial recharge, or alternately, some integrated combination of surface and aquifer storage. Costs of implementation 

should then be developed.

2. Consider all other aspects of water use, as well, and prepare a total 

integrated plan for future management of water resources in Qatar. 

This water management plan should include recommendations for an 

organizational structure to administer the plan and apportion and 

regulate use of water for all purposes.

CONCLUSIONS AND RECOMMENDATIONS

1. Ground-water extractions for agriculture in northern Qatar are greatly 

in excess of natural recharge. It was estimated, in 1980, that quality 

of ground water (in terms of dissolved solids) was declining at a rate 

of 5 percent per year. Extractions for irrigation have increased by 

almost 20 percent from 1980 to 1984.

2. Most water for irrigation is withdrawn from wells that are open to 

both the Rus and Umm er Radhuma aquifers, which are separated by an 

aquitard. The majority of net extraction is from the more highly 

transmissive Umm er Radhuma aquifer, which contains saline water at 

some depth. The Rus aquifer may essentially be in equilibrium 

between extraction and recharge from irrigation return water.

22
3. The only means of indefinitely maintaining even the present level of 

agriculture is the availability of some additional source of freshwater for irrigation. Use of desalinated seavater for artificial 

recharge on a large scale has been proposed. This scheme appears 

feasible from present knowledge. Artificial recharge would offer 

the advantages of stabilization or retardation of deterioration in 

quality of ground water; aquifer storage and transmission of 

desalinated seawater; and maintenance of a standby supply of potable 

water.

4. Artificial recharge should be by injection to the upper part of the 

Umm er Radhuma aquifer. A hydrogeologic appraisal should investigate 

and document the capability of the Umm er Radhuma aquifer to receive 

and store injected water, and the degree of efficiency with which 

this water may be recovered for use. Results will indicate the best 

areas for injection of recharge water; the optimum methodology for 

injection; and the total volume that it will be practical to inject, 

store, and recover. Total costs of the hydrogeologic appraisal are 

estimated to be QR. 5,362,000.

5. A management appraisal should be made concurrent with the hydrogeologic appraisal. The management appraisal should develop plans 

and costs for implementation of artificial recharge; it should also 

consider all other aspects of water use in Qatar and prepare an 

integrated plan for future management of water resources. The integrated plan should recommend an organizational structure to administer the plan and to apportion and regulate use of water for all 

purposes.

6. Proposals for the management appraisal should be solicited from 

international water-resources engineering firms who have the 

resources to provide all technical expertise required. The hydrogeologic appraisal may be handled by personnel of the Government of 

Qatar, or alternately, may be included in the contract for the management appraisal.

23
REFERENCES CITED

Eccleston. B. L., Pike. J. G., and Harhash, I, 1981, The water resources of 

Qatar and their development: Volumes I-III: United Nations Food and 

Agricultural Organization, Technical Report No. 5, Doha, Qatar.

Eccleston, B. L., and Harhash, I, 1982, The hydro-geology of Qatar: State of 

Qatar, Ministry of Industry and Agriculture and United Nations Food and 

Agricultural Organization; Water Resources and Agricultural Development 

Project-Phase III.

Harhash, I. E., 1984, Groundwater recharge estimates for the period 1972-1983: 

Ministry of Industry and Agriculture, Department of Agricultural and Water 

Research; Doha, Qatar, April 1984.

Merritt, M. L., 1983, Subsurface storage of freshwater in south Florida: a 

digital model analysis of recoverability: U.S. Geological Survey OpenFile Report 83-536, 73 p.

Merritt, M. L., Meyer, F. W., Sonntag, W. H., and Fitzpatrick, D. J., 1983, 

Subsurface storage of freshwater in south Florida: a prospectus: U.S. 

Geological Survey Water-Resources Investigations Report 83-4214, 69 p.

Vecchioli, John, 1976, Preliminary evaluation of the feasibility of

artificial recharge in northern Qatar: U.S. Geological Survey Open-File 

Report 76-540, 47 p.

24
APPENDIX 

Work Plan for the Hvdrogeologic Appraisal

This appendix is prepared to furnish more details for conducting the 

hydrogeologic appraisal. It is intended mainly to be used as a guideline, 

assuming that the appraisal is made by personnel of the Government of Qatar. 

The work plan should be used in close conjunction with the main text of this 

report.

The purposes of this hydrogeologic appraisal are:

1. To investigate and document the capability of the Umm er Radhuma

aquifer to receive and store injected water, and the degree of efficiency with which it may be recovered for use, and;

2. to interpret these results of investigation in terms of best areas for 

injection of recharge; the optimum methodology (rates, length of 

cycles, etc.) for injection and recovery; and the total volumes that 

it is practical to inject, store, and retrieve.

Successful completion of this hydrogeologic appraisal will require a 

2-year period of field investigations and the full-time services of two hydrogeologists, or ground-water hydrologists. One of these project hydrologists 

should have at least 5 years experience in areal ground-water investigations, 

and a significant part of this experience should be in the quantitative aspects 

of hydrology of carbonate aquifers. The other project hydrologist may be a less 

experienced individual, but should have a minimum of 2 years of experience in 

ground-water investigations. These project hydrologists will require full 

logistics support for their office and field activities (i.e., supplies, 

vehicles, field assistance, etc.) throughout the entire period of investigation.

The project hydrologists will also require the continuing availability, 

in advisory capacity, of a consultant in the area of artificial recharge, and 

periodic assignment of specialists in the areas of hydraulics and geochemistry 

of carbonate aquifers. These advisors and specialists may be senior technical 

personnel of the Government of Qatar; or they may be consultants on loan from 

other agencies, as appropriate. Hereinafter, they are referred to as project 

advisors.

It is suggested that the project hydrologists be available for a 3-month 

period prior to beginning the 2-year period of field investigations. This 

will allow them to accomplish some necessary preliminary work in both office 

and field and become thoroughly familiar with the project area. The preliminary work should include the organization of a data base for use during 

the investigation. A large amount of good background data (well records; 

ground water with withdrawals, levels, and quality; etc.) are available in the 

files of the Department of Agricultural and Water Research and other agencies 

of the Government of Qatar. Then data should be examined by the project 

hydrologists, and selectively screened into a working data base for the 2-year

25
investigation. Consideration should be given to computerization of the data 

base at this time. Contracts for test drilling, well logging, and aquifer 

testing will also need to be prepared. Preliminary work in the field may 

include collection of new data from specific capacity tests and, possibly, 

some more rigorous aquifer tests by use of existing wells and well fields.

Successful completion of the project should include preparation of a 

report to (1) document results of all field tests and experiments, and (2) 

draw final conclusions and recommendations. Early in the investigation the 

project hydrologists should plan the final report and prepare a working outline. Work on the report should then proceed during the investigation as 

progress is made and results become available.

When supplied with support in the areas of logistics and technical advice 

and support, the project hydrologists should have responsibility for carrying 

out all aspects of project work. The senior project hydrologist should be 

designated as project chief, and have the first-line responsibility over 

day-to-day activities.

The hydrogeologic appraisal will include test drilling; geophysical logging; aquifer testing; and recharge-recovery experiments at four sites in 

northern Qatar. These sites should be strategically located in each of the 

four quadrants of the general area that is enclosed by the 1,000 mg/L contour 

of the September 1982 map of dissolved solids concentrations.

Sites will be selected by the project advisors. Criteria to be used for 

selection are, in order of priority:

1. A source^'of water, from the Rus aquifer, for injection. Dissolved

solids concentration should be less than 1,000 mg/L. Quantities available should be at least 5 L/s, and greater quantities are suggested if 

available.

2. An area where the potentiometric surface of the Umm er Radhuma aquifer 

is not affected by pumpage. If this is not possible, then choice will 

be made on basis of the least affected areas that are available.

3. A generally central location within the quadrant.

 'NOTE: The source of water may be from existing well fields in the Rus 

aquifer, if the other criteria are met for the site. If not, new wells in the 

Rus aquifer will have to be drilled to furnish the source of injection water.

26
The remainder of this work plan is developed around the six blocks of 

activity, or "work elements," that must be accomplished for successful completion of this hydrogeologic appraisal. These work elements are discussed below, 

in general chronological order, as they should be accomplished at each site. 

Then, an overall timeline is included at end of discussion.

I. A test hole should be drilled to depth where the formation water has 

dissolved solids content of at least 10,000 mg/L. During drilling, 

continuing observations should be made of the changes in lithology; 

salinity; water levels; and water yield of the borehole. The percussion method of drilling should be used because it lends best to continuing collection of these data during drilling.

The drilling should be done by qualified contractors, with percussion 

drilling equipment that is readily capable of drilling and obtaining lithologic 

and water samples to total depth of 200 m. The project hydrologists should 

assist in preparing the technical specifications and descriptions for the 

drilling (as well as all other) contracts.

Major duties of the project hydrologists during test drilling will be to 

continually monitor and collect samples during all aspects of the drilling 

operations, and to maintain complete logs of lithology, to include notes on 

changes in drilling conditions; changes in water levels and quality; and any 

other pertinent details related to the drilling operation. The water-quality 

parameters to be measured during drilling are specific conductance and temperature. Each test hole should be drilled to total depth of 200 m to allow 

maximum correlation between holes (dissolved solids are expected to be in 

excess of 10,000 mg/L at this depth). At bottom of each test hole, a composite 

water sample should be collected for laboratory analyses of major ions and 

other parameters as appropriate.

Equipment needed during test drilling are the common tools for observing 

test drilling and water quality. It is important that the conductance meter 

used be maintained in accurate calibration.

II. Borehole geophysical logs should be obtained for the completed test 

borehole to include* as a minimum: caliper: electrical resistivity 

and spontaneous potential; borehole fluid conductivity and velocity; 

and natural gamma.

The geophysical logging should be done by qualified contractor. The logs 

should be made on an open borehole containing the native formation water. The 

project hydrologist should observe all geophysical logging operations and, as 

appropriate, incorporate notes on logging conditions into their records of test 

drilling observations.

Upon completion of geophysical logging all data and results should be 

reviewed and the project hydrologist (with assistance, as necessary, from the 

project advisors) will select the section of borehole to be used for aquifer 

testing. The drilling contractor will then convert each of the four test 

boreholes to test wells, as stipulated below.

27
III. The test borehole should be converted to use as an aquifer and

recharge-recoverv test well for the upper part of the Umm er Radhuma 

aquifer bv (a) grouting the bottom part of the borehole with cement 

to seal off to a depth where the salinity does not exceed a maximum 

of 4,000-6,000 mg/L, and (b) sealing off the Rus aquifer bv 

installing casing to the Rus-Umm er Radhuma Formations contact. A 

minimum of 5 m thickness is suggested for the aquifer test-injection 

zone, if possible to achieve without exceeding a residual dissolved 

solids content of 4,000-6,000 mg/L in the Umm er Radhuma aquifer.

Major duties of the project hydrologists during this period are to observe 

construction and ensure that the selected section of borehole is isolated as 

the test-injection zone.

IV. Four piezometers should be installed at each site three to monitor 

the Umm er Radhuma aquifer only, and one to monitor the Rus aquifer 

only.

The project hydrologists should select spacing and depth of these piezometers, based on results of drilling and geophysical logging, and observe their 

construction to ensure its being done properly.

The three Umm er Radhuma piezometers at each site should (1) have the Rus 

aquifer sealed off by installation of casing to the Rus-Umm er Radhuma 

Formations contact, and (2) be open to the upper 5 m of the Umm er Radhuma 

aquifer. Radial spacing of the three piezometers at each site is suggested as 

about 30, 100, and 300 m from the test injection well.

The single Rus aquifer piezometer at each site should be open to most of 

the saturated thickness of the Rus, but should not penetrate below the top 

of the aquitard that separates the Rus aquifer from the Umm er Radhuma aquifer. 

The Rus aqifer piezometer should be a radial distance of 30 m, or less, from 

the test-injection well, but should be on the opposite side from the closest 

Umm er Radhuma well.

V. Pumping tests of estimated 1-week duration should be made to determine the transmissivity and storage coefficients of the Umm er Radhuma 

aquifer, and to investigate the nature of hydraulic connection between 

the Rus and Umm er Radhuma aquifers.

Responsibility of the project hydrologists during aquifer tests is to 

coordinate all data collection, as well as to personally collect data. The 

test-injection well at each site should be pumped at a constant rate for a 

7-day period; and water level changes should be recorded for the pumped well 

and the four piezometers. The pumped rate should be a minimum of 10-15 L/s, 

though considerably higher rates are suggested if possible. Water level 

changes should be collected from continuous recorders installed on, as a 

minimum, the Rus aquifer and the nearest Umm er Radhuma aquifer piezometer at 

each site.

28
These recorder records should also have been maintained for at least a week 

prior to beginning a test. At end of pumping, water-level recoveries 

should be measured in all wells until equilibrium under non-pumping conditions is approached.

The project hydrologists should analyze all drawdown and recovery 

water-level data from the aquifer tests in consultation with the project 

advisors. In analysis, it is particularly important to obtain (1) representative values for transmissivity of the injection zone in the Umm er 

Radhuma, and (2) an indication of the degree of hydraulic connection 

between the Rus and Umm er Radhuma aquifers. For these reasons it is very 

important that casing be properly seated (in the test well and Umm er 

Radhuma piezometers) so that interaquifer pressure transmission does not 

occur through improperly sealed boreholes.

Quality of ground water should be monitored throughout the aquifer 

test(s). This may consist of collecting water samples for laboratory 

analyses of major ions at beginning and end of the test, and monitoring of 

specific conductance during the test. Disposal of water pumped during 

aquifer tests may be a problem, because there will likely be no surface 

drainage available to convey water from the test site. Portable discharge 

pipe should be used to convey water as far as practical away from the site, 

where it will probably accumulate in a shallow depression and begin seeping 

back into the Rus aquifer. This factor should be considered in analyses of 

test data, because it could result in rise of water levels in the Rus 

aquifer during aquifer testing.

Equipment needed during aquifer tests are those standard tools for 

measuring water levels and field quality of ground water. Water levels 

should be measured by use of a wetted, steel tape rather than electric 

tape, and (as discussed above) continuous water level recorders should be 

installed on at least two of the piezometers. The project hydrologists will 

need assistance of several additional personnel during aquifer tests in 

order to continually man the site and collect data over a week-long period.

VI. A series of recharge-recovery cycle experiments should be made for 

an estimated total period of 90 days at each site. For planning 

purposes it is suggested that each cycle be about 2 weeks in 

length (about 1 week of injection followed bv withdrawal until the 

appropriate level of dissolved solids concentration is reached). 

This would allow collecting data over a total of six complete 

recharge-recoverv cycles at each site.

Responsibility of the project hydrologists during recharge-recovery 

experiments is to coordinate all data collection as well as to personally 

collect data. The experiments at each site are estimated to require 90 

days, and data collection will be similar to that for the conventional 

aquifer tests. Thus the same types and numbers of equipment and additional 

personnel are needed, as for the aquifer tests.

29
The recharge-recovery experiments will involve injection of fresh 

water, with attendant monitoring of water levels in the injection well (and 

in all piezometers) followed immediately by withdrawal, with attendant 

monitoring of head changes and water quality until dissolved solids concentration of the recovered water reaches an arbitrary limit of 1,000 mg/L. The 

recovery efficiency for the completed cycle may then be computed, and subsequent cycles are then conducted.

The purpose of these recharge-recovery experiments is to obtain understanding of the recharge efficiency (or range of values for recharge efficiency) that may be achieved with the Umm er Radhuma aquifer in northern 

Qatar. There are no rigidly established procedures for conducting these field 

tests. The following recommendations derive from a combination of results of 

investigation in central and south Florida and the author's observation of 

hydrogeologic conditions in northern Qatar:

The source of water for the injection experiments will be 

from wells in the Rus aquifer, either existing wells in one of 

the Government well fields, or new wells drilled specifically as 

a source of water for the experiments. The Rus aquifer source 

should be capable of maintaining a minimum injection rate of 

5 L/s, though higher rates are recommended if available from 

the Rus at each site. (NOTE: Assuming availability of injection water, it is recommended that injection rates not cause 

more than 10 m of head buildup in the injection well).

Six complete recharge-recovery cycles are suggested for the 

first experiment site. For the first cycle, water should be 

injected for about 1 week and then recovered at the same rate 

until the dissolved solids concentration reaches 1,000 mg/L. 

Rates and times may then be varied to some degree during the 

remaining five cycles, at discretion of the project hydrologists 

and advisors.

Following completion of experiments at the first site, it 

is important that all project advisors be consulted in analyses of 

the data and planning of the subsequent experiments. Until that 

time, however, it is premature to plan the sequence and duration 

of recharge-recovery experiments at the remaining three sites. 

It is possible, for example, that results of the first experiment may indicate the need for longer-term experiments at one 

(or two) of the remaining three sites rather than the 6-cycle 

90-day tests that have been used for planning purposes.

The project advisors will again need to be consulted during the final 

months of the 2-year period of field study (that is, at or near the end of 

the recharge-recovery experiments). At that time the project hydrologists 

should have a working draft report of their documentations of all field 

work results. Then the project hydrologists and advisors will jointly make 

final conclusions and recommendations.

30
A general timetable for the hydrogeologic appraisal is included below;

1st 2nd 

year year 

field field 

work work

Review of all available data; organization of 

data bases and references; preliminary 

collection of selected field data; preparation 

of contracts. X

Test drilling; test and piezometer well 

construction.

Conventional aquifer tests. 

First 90-day recharge-recovery tests. 

Consult all project advisors. 

Remaining (2-3) recharge-recovery tests.

Consult all project advisors; 

finalize documentary report; 

conclusions, and recommendations.

X:X: :

...

...

X:X:X:X

: : :X

31