THE NUIZIAN ARTESIAN BASIN,ITS REGIONAL HYDROGEOLOGICAL
ASPECTS A N D PALAEOHYDROLOGICAL RECONSTRUCTION
I. H. HIMIDA
Water Resources Division,Desert Institute,Cairo,United Arab Republic.
SUMMARY
In the present study different geological,hydrogeological and hydrogeochemical data are used for
interpretation of the regional hydrogeological aspects and evolutionary history of one of the most
extensive artesian basins in the world, in North-EastAfrica Hydrogeochemically,the area of the
artesian basin is subdivided into three main regions that contain differentgenetic types of ground
water. Many hydrogeochemical zones are recognized and described within the areas of these
hydrogeochemicalregions.
In the evolutionary history of the artesian basin three main stages are outlined, the most
important of which extends from the middle of the Early Cretaceous up to the end of the Pliocene
period. For the interval from the Late Eocene till the present time the hydrogeological aspects of
the artesian basin are illustrated by a series of palaeohydrogeological schematic maps.
Many of the important hydrogeological aspects of the area of study are explained on the basis
of a palaeohydrogeological reconstruction of the artesian basin.
RÉSUMÉ
L E BASSIN ARTESTEN D E NUBIE-DESCRIPTION D E SES REGIONS HYDROCEOLOGIQUES ET RECONSTITUTION PALEOHYDROGEOLOGIQUE
Dans la présente étude,l’auteur a utilisé différentes données géologiques,hydrogéologiques
et hydrogéochimiques pour donner une interprétation des aspects hydrogéologiques
régionaux et ppur retracer l’histoire de l’évolution de l’un des bassins artésiens les plus
btendus du monde, au nord-estde l’Afrique. D u point de vue hydrogéochimique,ce bassin
artésien se subdivise en trois régions princpales où la genèse des eaux souterraines a été
différente. A l’intérieur de ces régíons, l’auteur dist.ingue de nombreuses zones hydrogéochimiques dont il donne une description.
Retraçant l’évolution du bassin artésien,il donne un aperçu des trois stades principaux
dont le p!us important va du milieu du crétacé inférieur à la fin du pliocènc. Pour la période
allant de I’éocène supérieur à l’époque actuelle, les caractéristiques hydrogéologiques d u
bassin artésien sont illustrées par une série de cartes schématique paléohydrogblugíques.
Nombre de caractéristiques hydrogéologíques importantes de la zone étudiée sont
expliquées à partir d’une reconstitution paléohydrogéologique du bassin artésien.
The present study deals with the regional hydrogeological and palaeohydrogeological
aspects of an extensive artesian basin that covers nearly the whole territory of the
Libyan Desert as well as a part of the desert area extending to the east of the Nile
Valley (the Eastern Desert).
The Libyan Desert constitutesthe north-easternpart of the African Continent.It is
one of the most arid regions in the world, where on the greater part of the desert area
the amounts of rainfall and, consequently, runoff are practically negligible.
Previously, it was c o m m o n to give the name “Sahara” to the whole desert area
extending in North Africa. Since the beginning of the 20th century, it has been the
custom to restrict the name “Sahara” to the western part of this desert area,while the
eastern part has been given the name “the Libyan Desert”.
The western boundaries of the Libyan Desert, which separate it from the Sahara,
can be located along the series of highlands running north-west of El Fashir and
3 70
T h e Nubian Artesian Basin -regional hydrogeological aspects
consisting of the Ennedi, Eridi, Tibesti, and T u m m o Plateaus and the Hammadas
desert area of Fezzan.The eastern side of the Libyan Desert is well defined by the Nile
Valley. The southern regions of the desert are limited by the northern reaches of
Darfur and Kordofan in Sudan, while the desert area extends northwards until it
reaches the Mediterranean.
The whole area described above constitutes one huge unbroken tract of true desert
area which is characterized by extreme aridity. The only exception is the narrow
littoral zone extending along the Mediterranean coastal area and characterized by
scanty rainfall, seasonal irregular runoff and poor plant cover. However, moving
southwards,the amount of rainfall rapidly diminishes and the plant cover becomes so
scarce that within about 150-200k m from the coast the desert area is totally devoid of
any plant cover.
The only islands of life within the interior of this huge desert area are the oases
regions which are located in a series of depressions in the desert plateau and owe their
existence exclusively to the ground-waterresources.The most important of these oases
are Kharga, Dakhla, Farafra, Bahariya and Siwa Oases in the Egyptian part of the
Libyan Desert and Ghabub and Kufra in the Libyan part.
Since 1957, much attention has been paid to developing the oases regions in the
Western Desert of the U.A.R.Development programmes are included in what is called
the “New Valley Project”. This is a great project of land reclamation in the oases
regions, where water supplies are planned to be totally obtained from ground-water
resources. Accordingly, pre-development studies dealt mainly with the problems of
evaluating the ground-waterpotentialities in these regions.
Two hundred and eight-fourexploratory water wells, ranging in depth from 400 m
to 1200 m, were drilled in the different oases regions during the last 10 years for the
purpose of carrying out subsurface geological studies and conducting various
hydrological observations. In addition to these wells a number of exploratory oil wells
and water wells had previously been drilled by the oil companies in different regions of
the Libyan Desert. These wells provide an important source of information about the
subsurface geology and the hydrogeology of the northern part of the Libyan Desert,
where some of the wells penetrated a sedimentary section more than 5000 m in
thickness,
Many types of survey were carried out in different parts of the Libyan Desert of the
U.A.R.,
with concentration on the oases regions. These included topographical surveys
of different scales, geological surveys,gravimetric surveys,and aeromagnetic surveys,
in addition to electric well logging and conduction of electric profiles in some areas.
Hydrological tests and observations included periodic measurement of ground-water
levels and discharges,periodic analysis of ground-water samples, and the carrying out
of pumping tests for some wells.
The present study includes analysis and interpretation of the results of the
above-mentioned research with the purpose of establishing the regional hydrogeological aspects of the ground-waterbasin extending below the surface of the Libyan
Desert, and of reconstructing its hydrogeological conditions in the different geological
periods throughout its formation.This palaeohydrogeological approach proved to be
of great help in tackling the problems of origin and formation of the ground water of
the Libyan Desert..
PHYSIMIZAPHY
The Libyan Desert exhibits distinctive physiographic aspects which differ considerably
from those of both the Sahara region extending on the western side and the Arabian
37 1
I. H.Himidu
Desert lying to the east of the Nile Valley. It is generally characterized by the
following main aspects: (i) extreme aridity, (ii) absence of drainage lines, (5)
uniformity.
The Libyan Desert, together with the Sahara and Arabian Deserts,is included in the
great arid belt that extends from the Atlantic Ocean through North Africa and the
Near and Middle East and ends in South-East Asia. However, the Libyan Desert is
considered the most arid region within this belt. Both the Sahara region and the
Arabian Desert are characterized by a more,mild climate than the Libyan Desert.
An annual amount of rainfall ranging between 150 and 200 mm precipitates
seasonally on the coastal zone of Libyan Desert. Other than in the coastal area, the
amount of rainfall becomes less than 20 “/year
on the vast interior territory of the
desert area. Appreciable amounts of rainfall can be recorded in the Central Sudan,
where it increases considerably southwards, and also on the highlands bordering the
Libyan Desert on its south-westernand western sides.
Besides the extreme aridity, other distinctive features of the Libyan Desert are its
uniformity and the absence of drainage lines. The whole interior of the Libyan Desert
is entirely flat and lacks any sign of drainage lines belonging to a comparatively recent
age. Drainage lines are abundant only at the peripheries of the desert plateau,
especially in the coastal area. Both the uniformity of the desert surface and the
absence of drainage lines are features resulting from the extreme aridity of the area.
Physiographic Regions of the Libyan Desert
In spite of the apparent homogeneity and uniformity of the Libyan Desert, closer
examination of the desert surface permits the recognition of six physiographic regions,
each of which exhibits a particular landscape,They are briefly described as follows:
1) The Northern Mediterranean Coastal Plain: this is a relatively narrow plain
running in an east-west direction parallel to the coast line. It is bounded at its southern
side by a low escarpment rising about 100 m above sea level. The coastal plain is
characterized by the occurrence of a series of elongated ridges oriented in the same
direction as the plain and alternating with shallow depression areas. Such ridges are
composed of oolitic limestones, and are described as consolidated ancient littoral
dunes,
2) T h e Marmarican Homoclinal Plateau; forming the extreme northern area of the
Libyan Desert plateau. It extends from the Nile Delta westward to Cyrenaica and from
the North Mediterranean Coastal Plain southward to the Qattara Depression. This is an
almost flat plateau sloping regionally both to the north and to the west and rising from
300 m to 400 m above sea level. It consists mainly of Middle Miocene intercalations of
limestones and sandstones.
3) T h e Limestone Plateau; covering an extensive area to the west of the Nile Valley.
It is a plateau consisting of compact limestones of Eocene age underlain by softer
formations of Cretaceous age. It extends southward until it ends by an escarpment
about 300 m high overlooking the Sandstone Plateau.
4) T h e Sandstone Plateau; sometimes referred to as the Sandstones Wide Plains
(Shata, 1967). It covers more than half the area of the Libyan Desert and forms an
extensive plateau extending from the Nile Valley in the east to the Tibesti and Ennedi
highlands in the west and from Kordofan region on the south to the Limestone Plateau
in the north. This plateau consists essentially of rocks of Nubian Series.
5) T h e Great Sand Sea: this is the largest sand area in the world. It covers an
extensive area on the extreme western frontiers between Egypt and Libya.
6) The Libyan Desert Depressions: these are natural excavations in the desert
3 72
The Nubian Artesian Basin -regionul hydrogeological aspects
plateau ranging in depth from 1 O0 m to 400 m.They are generally classified into three
groups. The northern group of depressions includes the Qattara (the largest depression
in the Libyan Desert), Moghara, Qarra, Siwa and Ghabub Depressions; the middle
group includes the Bahariya and Faiyum Depressions while the southern group
includes the Farafra,Kharga and Dakhla Depressions.
The depressions of the Libyan Desert, according to most of the recent authors,owe
their origin to tectonic factors at the first stages of their development.These tectonic
factors, later on,were supplemented by weathering and erosion action along lines of
weakness.
Among the above-mentioned physiographic regions of the Libyan Desert, the
depression areas are especially interesting as they include the oases regions and the
areas liable to be reclaimed.
GEOLOGY
General Regional Geological Aspects
The Libyan Desert, in respect of its regional geological aspects, represents a huge
monoclinal structure where the older formations always outcrop at the southern
localities, whereas, moving northwards, they generally increase in thickness and
disappear under the younger formations.
Along the coastal zone of the Red Sea,as well as in the most southern regions of
the Libyan Desert, are outcrops of rocks belonging to the crystalline basement
complex which are composed of granites,granodiorites, diorites,gneisses,schists,etc.
The age of these rocks in most localities is assigned to the Precambrian. However,in
many localities intrusive rocks of younger ages are recorded (see Fig. 1).
Moving from the southern localities of the Libyan Desert northwards,the rocks of
the basement complex are gradually overlain by a series of mostly unfossiliferous
formations consisting of sands, sandstones, clays and shales which are commonly
termed the ‘NubianSeries’.
The Nubian Series varies in thickness from some fewtens of metres in the northern
regions of Sudan to about 250 m in the southern localities of Kharga Oasis, 900 m in
the northern localities of the same oasis,and about 1800 m in Bahariya Oasis, while it
attains a thickness of more than 3500 m in the northern localities of the Libyan
Desert.
Regionally, the Nubian Series changes gradually from mainly continental sandy
facies in the southern regions of the Libyan Desert to intercalations of sands,
sandstones and clays of alternating continental and shallow marine facies in the central
regions of the desert area, to mainly marine facies in the northern regions where it
consists of thick beds of clays intercalated by beds of limestones, dolomites and
sandstones.
The Nubian Series in most regions of its extension in the Libyan Desert lacks any
guide fossil by which it can be stratigraphically subdivided. However,in the northern
regions of the Libyan Desert,where marine facies dominate,a limited number of fossil
species was recoroed in the Nubian Series penetrated by the deep exploratory oil wells.
According to these findings,the section of the Nubiaa Series in these regions proved to
comprise rock formations of Cambrian,Devonian,Carboniferous,Jurassic,and Lower
and Upper Cretaceous ages. Generally,it may be concluded that the Nubian Series,by
their stratigraphical position,range from the Cambrian to the Upper Cretaceous.
To the north of the Kharga Oasis region, the Nubian Series are overlain by rock
series of proper marine facies consisting of phosphate beds, chalky limestone,and
3 73
I!
.
.
I
I. H.Himidu
2
374
- - - - - - - ----I
Y Y Y Y Y LI--
T h e Niibiaii Artesian Basiil -regioid hydrogeologicut nspecrs
LEGEND TO FlG.1
Quaternary deposits.
Miocene rocks,limestone.sandstone. and sandy clays.
Palaeocene rocks (Palaeocene-Eocene). clays. shales and limestone.
Senonian rc.:ks. chalk and limestone.
Marstrichtian rocks. purplish clays in Kharga and Dakhla Oascs.
Ccnomanian rocks, sandsstone,sometimes with clayey intercalations
Lower CretacccÜs rocks,sandstone,with clay intercalations and limestone.
Jurassic rocks. sandstcne,clays and shales.
Paleozoic and Mesozoic undifferentiatcd rocks. sandstcae,with dolomite intercalations.
Palaeozoic (Cambrian and Devonian?) rocks? sandstone. with siltstones.
igneous and metamorphic rocks of basement complex.
Zcne or mainly fresh water of infiltration corigin with mineralization
lower than 1 g/l.
Zone or brackish water of mixed origin within the Nubian in the
region of Qattara Depression.
Zone of highly saline ground water and brines of originally sedimentation origin.
Zone of salty and saline grcund water in the Post-Nubian sediments
in the northern part of the artesian basin.
Fault.
shales of Upper Cretaceous and Palaeocene ages. In Farafra Oasis, the Nubian Series
are overlain by Upper Senonian chalk and crystalline limestones.
Shales,limestones, chalky Iimestones and argillaceous limestones of Palaeogene age
cover a relatively extensive territory of the Libyan Desert. In the southern regions of
the Libyan Desert, Palaeogene formations (generally) conformably overlie the Upper
Cretaceous formations, while in the northern regions (at least partially) the Upper
Cretaceous formationsare overlain by Palaeogene rocks.
Continental, freshwater and marine deposits of Oligocene age consisting of
coarse-grained sandstones,conglomeratesand shales occupy only a very limited area of
the northern region of the Libyan Desert. At the southern localities of the Siwa Oasis
region, Palaeogene formations gradually disappear underneath the Miocene formations.
Marly limestones, sandstones, and shales of proper marine facies overlie the
Oligocene deposits in the northern part of the Libyan Desert. These Miocene rocks
constitute the Marmarican Homoclinal Plateau.
Pliocene deposits are recorded in some regions in the most northern part OC the
Libyan Desert and the Nile Valley. They consist of both continental and marine
deposits composed of sands, clays, gravels and conglomerates. They are largely
developed in the form of elevated beaches in the northern part of the Libyan Desert.
Pleistocene and Recent deposits are represented by fluvial deposits in the Nile
Valley and Delta, gravel terraces bordering the Nile Valley, lacustrine deposits covering
the ground surface in some of the depressions, wadi fillings at the edges of the desert
plateau and in the Eastern Desert, consolidated dunes along the coastal zone of the
375
I. H.Himida
Mediterranean, and the widespread free-moving sand deposits in the form of sand
dunes and sand sheets.
Regional Geological Structure
From the structural point of view, the Libyan desert represents a part of the shelf
areas that bound the Arabo-Nubian Massif (the Shield area). The rocks of the
Arabo-Nubian Massif constitute the mountain range extending along the Red Sea.
They also outcrop at some localities in the southern regions of the Libyan Desert.
The shelf area of the Libyan Desert,structurally,can be subdivided into two major
units: (i) the unstable shelf area (mobile area), (ii) the stable area.
The unstable shelf area constitutes the northern part of the Libyan Desert. The
boundary between this area and the stable shelf area is not well defined. However,it
can be tentatively traced from the central regions of the Sinai Peninsula in a
south-west direction, passing the Nile Valley at latitude 28' north, to the southern
regions of Farafra Oasis and eventually in a western direction crossing the Libyan
Desert.
The mobile shelf area of the Libyan Desert is characterized by a relatively complete
and thick section of sedimentary rocks belonging to the Palaeozoic, Mesozoic and
Cainozoic eras; the rocks of the basement komplex are generally situated at great
depths. This area has suffered more intensive tectonic movements throughout its
geological history. It is characterized by the occurrence of a series of major anticlines
and synclines oriented in a NE-SW direction; folds, overthrusts and diapirism are
common here.
The stable shelf area in the Libyan Desert extends from the regions where rocks of
the basement complex outcrop in Central Sudan and north-easternregions of Chad
northwards up to the contact between the stable and unstable shelf areas.This area is
characterized by a relatively thin section of sedimentary rocks and a shallow basement
complex.Tectonic featuresin the area indicate that tectonic movements have been less
intensive. A number of grabens and horsts cross this massif. Extensive but very gentle
domes are recorded;on the other hand,true anticlines are absent.Faulting prevails in
both tectonic units,but is more common in the stable shelf area.
HYDROGEOLOGY
Regional Hydrogeological Aspects
Ground water has been exploited and used for a long time in the oases regions of the
Libyan Desert by more numerous,and probably more prosperous,populations than at
present. Remains of hundreds of old wells are recorded in these regions.
Many hydrogeological aspects of some regio.ns of the Libyan Desert have been
described in the works of various authors. The works of such authors as Beadnell
(1908,1909), Ball (1927), Sandford (1935), Hellstrom (1940), and Murray (1952)
were mainly concerned with the problems of the source and directions of movement
of ground water in the Libyan Desert. On the other hand, the works of more recent
authors, such as those of Paver and Pretorius (1954), Pavlov and Burdon (1959), and
Himida (1965, 1966, 1967), have dealt mainly with the hydrogeological conditions of
the regions of Kharga and Dakhla Oases and quantitative studies of their ground-water
resources. Later on, the work of Omara et al. (1970) is concerned with the
hydrogeological conditions and origin of the ground water in the region of Farafra
Oasis.
376
The Nubian Artesian Basin
-regional lzydrogeological uspects
Regional hydrogeological aspects of the Libyan Desert were firstly touched on by
Ball (1927),who was the first to construct a water-levelmap for the Western Desert in
Egypt, using water levels from different springs and wells discharging from different
water-bearing formations. Later on, Sandford (1935), Hellstrom (1940)and Murray
(1952) modified Ball’s m a p and extended it to cover the whole of the Libyan Desert.
Obviously,these authors considered that the different water-bearingformationsin the
Libyan Desert constitute one ‘hydrogeologicalsystem’.However, because of the lack
of data at this period of time, they were not able to describe the configuration of the
‘hydrogeologicalsystem’in the Libyan Desert or its regional hydrogeological aspects.
From an examination of recent information, with consideration of the regional
geologicalstructure of the Libyan Desert,the hydrogeological and hydrological aspects
and hydrogeochemical zonation of the different water-bearing formations,it can be
concluded that the ground-water horizons described in the different oases regions
constitute only small scattered portions of an extensive multilayered artesian basin
that covers nearly the whole territory of the Libyan Desert and a great part of the
Arabian Desert to the east of the Nile Valley. From the structural geological point of
view, this is a major artesian monocline of the platform type. Hydrogeologically,it is
an artesian basin of the semi-closedtype where the different water-bearingformations
gradually disappear northwards under the younger formations and discharge only by
upward leakage through the overlying beds.
The eastern boundaries of the artesian basin can be strictly delineated by the series
of mountain ranges consisting of basement rocks and extending parallel to the Red Sea
coast. The southern boundaries can be defined by the outcrops of basement rocks in
different regions of North Sudan and in the north-eastern regions of Chad. The
western boundaries of the artesian basin cannot be sharply defined.However,they can
be tentatively traced along the localities where the rocks of the basement complex
either outcrop on the surface or are recorded at shallow depths (see Fig. 2). The
artesian basin thus covers an area of about 2.5 million square kilometres,including
nearly the whole territory of Egypt,the eastern part of Libya,the northern regions of
Sudan and the north-easternpart of Chad. According to its areal extent,the artesian
basin can be considered as one of the most extensive artesian basins in the world.
Considering the fact that the water-bearing formations of the Nubian Series
constitute the major and principal part of the structure of the artesian basin,the latter
was called by the present author “the Nubian Artesian Basin” (Himida, 1965).
Two main water-bearing complexes can be distinguished in the structure of the
Nubian Artesian Basin. The regional hydrogeological aspects of each water-bearing
complex are briefly described in the following:
(i) The Nubian Series Water-Bearing Complex; this is the main water-bearing
complex and is represented by the water-bearingformations and horizons contained in
the Nubian Series overlying the basement complex. Water-bearingformations of the
Nubian Series contain the main bulk of the ground-waterresources within the Nubian
Artesian Basin.
Nubian formations,wherever tapped by wells, are found to contain ground water.
In the regions of Kharga and Dakhla Oases the deep wells tapped more than 32
water-bearing horizons, kainly consisting of sandstone beds separated locally by
confining beds of clays. Subsurface geological studies and hydrogeological
investigations proved that both water-bearing horizons and water-confining beds have
no regional lateral extension,with the exception of an upper bed 80-180metres thick
of varigated clays which covers an extensive area in these regions.
In the New Valley area, the ground water of the Nubian Series is exploited in the
regions of Kharga, Dakhla, Mawhub West, Abu-Monqar,Farafra and Bahariya Oases
377
1. H.Himidu
SCHEMATIC HYDROGEOLOGICAL M A P OF THE NUi3lAN ARTESIAN
r.””
A m o moinly Cowred by proper Nubion Srrics formorioil,
À < m sovrrrd by volconic rocks.
Arco moinly covrrcd by rocks of the boscment camplci.
Boondory line of the franc of highly SbfrOe ground wolcr ond brines of origiml@rd!mentotron grncsis ,io the
Post-Nubion wotcr-beoring crrmplrx ,
Boundory lrne of fhe ironr of highly s d m c wotcr and brines io rhc deeper Nubion Serks wotcr-b#oring
complex lin rhe ~olocozoic fwmotions~.
Boundory line bctwcm tnc rcgions ofbmchshartcsmn Wore< 01 mixed o d g h ond the fresh orferhn Water of
moinly infiltrotion origin
Suggested mom cntchmenf b r m s of the Nubion Artclion ~ a s min rrcenr rimd.
Mom orcos of notum1 discharge of Ihr N o b m n Artesion Sosin .
o~ artlfic,d cnpioit~tronof groundwaterin thc orresan barin.
r.m
Worer-lcd contour liner of Ihr Nubion Serrer W o h l beormg complcx lin mcfres o b w c seo Irurll
Moi” diriclions of rcchorge of ?he ortesran basin.
Suggested boundorics of the Nubion Irlesion BOSin.
OricntoNon of hydrogeological cross secrions 1 Fig. I J.
---
\
O
Z
A/A’
FIGUKE
2.
378
BASIN
The Nubian Artesian Basin
-regional hydrogeological usgects
either by shallow native wells,or by deep wells,or by both. Shallow native wells,
ranging in depth between 30 and 150 m,tap the uppermost water-bearinghorizons of
the Nubian Series, while the deep wells,ranging from 300 to 1200 m in depth,tap the
middle and lower water-bearinghorizons in the above-mentionedregions.
Ground water of the Nubian Series in most regions of the Nubian Artesian Basin is
characterized by its high hydrostatic pressure. In most localities of the oases of the
Libyan Desert as well as in many localities along the Gulf of Suez there is a progressive
increase of ground-water hydrostatic pressure from the uppermost water-bearing
horizons to the lowermost ones.
Previously, nearly all the shallow and deep wells tapping the Nubian Series in the
oases regions were exploited under flowing regime.In present times a great number of
the wells stopped flowing as a result of intensive exploitation of ground water and the
consequent formation of regional cones of depression in some localities of the oases
regions. Future exploitation of ground water in these regions should be carried out
using adequate types of artesian pumps after investigating the possible exploitation
regime.
Another important aspect of the ground water of the Nubian Series in the oases
regions is its low mineralization compared with the mineralization of the ground water
contained in the Post-Nubian water-bearing horizons. It is very interesting to notice
that the mineralization of the ground water of the Nubian Series in most of the oases
regions decreases appreciably from the uppermost water-bearing horizons to the
lowermost ones,resulting in what is called “reverse zonation of ground-watersalinity”.
Ground-water temperature of the Nubian Series ranges from 25OC to 4OoC,
depending on the depth of the water-bearinghorizon.
(ii) The Post-Nubian Water Bearing Complex; this is represented by the
water-bearing horizons contained in the fissured limestones, sandstones and marly
limestones of the Upper Senonian,Eocene and Miocene formations extending to the
north of the Kharga-Dakhlaregions.
Ground-water potentialities of the water-bearing formations making up the
Post-Nubian water-bearing complex are much lower than for the Nubian Series
water-bearing complex. Moreover, geological,hydrogeological and hydrogeochemical
studies have proved that the water-bearingformations of the Post-Nubiancomplex are
mainly recharged by upward leakage of the artesian water contained in the underlying
formations of the Nubian Series,
Ground water of the Post-Nubianwater-bearing formationsis largely exploited in
the Farafra Oasis region (Upper Senonian water-bearing formations) and in the Siwa
and Qarra Oases regions (Middle Miocene formations) using shallow dug wells and
springs.
Water temperature in the shallow wells exploiting the Post-Nubian formations in
these regions ranges from 16OC to 28OC, depending on the depth of the discharged
water-bearingformation.Ground water is generally exploited under flowing regime.
The Nubian Artesian Basin, like all the other artesian basins, can be subdivided
laterally into catchment areas, pressure areas and natural discharge areas.
Although numerous regions on the different boundaries of the Nubian Artesian
Basin have been acting as catchment areas during certain past geological periods,as will
be explained later on, the most probable catchment areas in recent times can be
located on the highlands of north-eastern regions of Chad, central regions of Sudan
and probably on the Tibesti Plateau. This can be judged from the water-level contour
m a p (see Fig. 2). According to the water-levelcontour lines,ground-watermovement
takes place primarily from south-westto north-east.It is worth mentioning that the
water-level contour lines of the Upper Senonian water-bearing formations in Farafra
379
I. H.Himida
Oasis indicate that the movement of the ground water in these formations has nearly
the same trend as that of the underlying Nubian Series water-bearingformations.
Pressure areas of the Nubian Artesian Basin cover most of the basin area both in the
Libyan Desert and in the desert area to the east of the Nile Valley. Throughout these
areas, ground water in the water-bearing formations mostly occurs under hydrostatic
pressure.
The Nubian Artesian Basin being of a semi-closedtype,the natural discharge of the
ground water of the different formations takes place, at least partially,in a series of
depressions extending in the northern regions; such as the Qattara Depression, Siwa
Oasis, Ghabub Oasis and others.
Regional Hydrogeochemical Zonation of the Ground-Water-BearingFormations
Considering the ground-water mineralization,its main chemical types and mode of
formation within the Libyan Desert, the following hydrogeochemical regions and
hydrogeochemical zones can be recognized:
A. Region of Mainly Fresh G r o u n d Water of Infiltration (Meteoric) Origin; this
region covers a huge territory extending from tbe southernmost boundaries of the
artesian basin up to a latitude north of Bahariya Oasis. This area is mainly covered by
rocks of the Nubian Series, Ground water within this region is mainly fresh,and its
mineralization rarely exceeds 1000 ppm and in most cases does not exceed 500 ppm.
In some cases the mineralization of ground water is as low as 120-150ppm, as for
example in the case of some shallow wells in Bahariya Oasis and some of the deep
wells in Farafra Oasis,
According to the ground water chemical types,this region within the area of the
New Valley Project can be subdivided into the following hydrogeochemicalzones (see
Fig. 3):
(i) Zone of chloride-sulphate-sodium-calciumwater in the upper water-bearing
horizons of the Nubian Series in Dakhla Oasis.
(ii) Zone of bicarbonate-chloride-sodium-calciumwater;predominating in the lower
water-bearing horizons of the Nubian Series both in the El-Zaiyat region (midway
between Kharga and Dakhla Oases) and in the northern part of Kharga Oasis. Ground
water of this zone is characterized by the presence of appreciable amounts of
NaHC03.
(5)Zone of mixed water chemical types with predominance of bicarbonatechloride-sodium water in the lower water-bearing horizons and chloride-bicarbonatesodium water together with chloride-sulphate-sodiumwater in the upper water-bearing
horizons of the Nubian Series in the Ginah area (Kharga Oasis).
(iv) Zone of chloride-bicarbonate-sodiumwater in the southern localities of Kharga
Oasis.
(v) Zone of chloride-bicarbonate-magnesium-sodium water in the upper
water-bearing horizons of the Nubian Series in Bahariya Oasis. Ground-water
mineralization within these horizons is mostly very low. However, in some wells
ground water of mineralization exceeding 1 O00 p p m is recorded. This is mostly due to
continental salinization (secondary salinization).
(vi) Zone of chloride-sulphate-magnesium-sodium and chloride-bicarbonatemagnesium-sodium water in the Upper Senonian water-bearing formations in Farafra
Oasis. Mineralization of ground water within this zone generally ranges between 300
and 800 ppm. However,brackish and even saline water is recorded in some wells.This
is mainly due to the effect of continentalsalinization.
380
The Nubian Artesian Basin -regional hydrogeological aspects
25’
26’
27’
28’
29‘
JO’
31’
32’
33’
3
c
HYDROGEOCHEMICAL ZONATION MAP OF THE ARTESIAN WATER-BEARING HORIZONS
IN THE WESTERN DESERT OF U.A.R.
FIGURE
3.
381
I. H.Himidu
(vii) Zone of predominance of bicarbonate-chloride-calcium-magnesium(or
magnesium-calcium)water and less frequently chloride-bicarbonate-magnesium-sodium
water in the Nubian Series water-bearing horizons in Farafra Oasis. Mineralization of
ground water is extraordinarily low and does not exceed 300 ppm.
B. Region of Brackish and Salty G r o u n d Water of Mixed Origin; this extends from
the northern limits of the region where ground water of meteoric origin predominates
up to a latitude north of the Qattara Depression (see Fig. 3). This region,vertically,
comprises many water-bearinghorizons in the Post-Nubianformations as well as in the
upper part of the Nubian Series (see Fig. 1). Mineralization of ground water within this
region mostly ranges from 2000 to 10,000ppm.
Shallow wells and springs in Siwa and Qarra Oases and also in the Qattara
Depression,located within the above-mentionedregion,exploit water-bearinghorizons
of the Middle Miocene formations.A zone of mainly chloride-sulphate-sodiumwater is
recorded in both Siwa and Qarra Oases. Mineralization of ground water in these
localities ranges from about 2000 to 7000 ppm.
C. Region of Highly Saline Water a n d Brines of Sedimentation Origin; this extends
to the north of the above-mentioned region.Within this region all the water-bearing
formations under the surface ones are charged by highly saline water and brines.
Mineralization of ground water may attain a figure of 300,000ppm, and the
ground-waterchemical is predominantly sodium chloride. In vertical section,the upper
limits of this zone gradually become deeper southwards until it underlies the region of
brackish and salty ground water in the area of the Qattara Depression where it is
represented by the lower water-bearinghorizons of the Nubian Series (see Fig. 1).
The distribution and aspects of the above-mentioned different hydrogeochemical
regions and zones within the area of the Nubian Artesian Basin can be explained,to a
large extent,on the basis of a palaeohydrogeological analysis of the artesian basin.
PALAEOHYDROGEOLOGY
Palaeohydrogeological studies,generally,are concerned with the reconstruction of the
hydrogeological conditions of a region in the different geologicalperiods during which
it developed. Obviously,palaeohydrogeological analysis of a ground-waterbasin can be
of primary importance in solving the problems of origin and history of the ground
water contained in it.
Besides the present geological structure and hydrogeological conditions, the
palaeohydrogeological studies of the Nubian Artesian Basin were based on a great
amount of diversified data and information concerning its geological history,
palaeogeographical aspects, its palaeoclimates and the evolution of the landforms
within its area.
Reconstruction of the hydrogeological conditions of the Nubian Artesian Basin,
from the Middle Eocene to the present time,is translated into a seriesofschematic
maps (Fig.4).
For the construction of these schematic palaeohydrogeological maps of the Nubian
Artesian Basin,the following items were considered:
1) The areas covered by sea water.
2) The areas occupied by both continental and marine deposits.
3) Distribution of the different water-bearing formations within the area of the
artesian basin.
4)Regions of distribution of the main ground-watergenetic types,
3 82
T h e Nrthiari Artesiatz Basin
-regional hydrogeological aspects
383
I. H.Himida
5) Suggested main catchment areas and discharge areas of the artesian basin.
6) Regions of intensive tectonic movements affecting the regime,and directions of
movement of the ground water.
7) The main directions of ground-watermovements.
The main changes in the hydrogeological conditions of an area, especially the
changes in its hydrogeochemical aspects, and the trends in which these changes take
place are chiefly originated by the changes in the palaeogeographical environments of
this area. The most important changes in the palaeogeographical environments are the
interaction between the sea environment and the land environment.The transgression
of the sea on a land area may result in the.xommencement of a hydrogeological cycle,
the first part of which (the sedimentation period) is characterized by the replacement
of the already-formedfresh infiltration (meteoric) ground water by saline sea water
and formation of sedimentation sea water (connate water) in the newly deposited
sediments in the marine environments.The second part of the hydrogeological cycle
generally begins with the regression of the sea. This period (infiltration period) is
characterized by the infiltration of fresh meteoric water into the water-bearing
formation, resulting in the gradual dilution of the already-formedsea water, washing
of the water-bearing formation,displacement of the highly saline water seawards and,
eventually,freshening of the ground water.
Four major stages can be outlined in the geological history of the Nubian Artesian
Basin:
A,The first stage extends from the beginning of the Palaeozoic era up to the middle
of the Early Cretaceous. During this period, geological data indicate that the
northernmost part of the area now occupied by the Nubian Artesian Basin was
repeatedly covered by sea water, resulting in the occurrence of many hydrogeological
cycles.The history of the area during this stage can be summarized as follows:
(i) The first hydrogeological cycle begins with the transgression of the Cambrian sea
southwards in the north of Gondwanaland. The shore line probably reached the
latitude of the present location of Bahariya Oasis (Amin, 1961). During this period,
for the first time, was initiated the process of replacement of the meteoric infiltration
ground water by the saline sea water in the already-existing thin mantle of the
continental deposits. At the same time, during the sedimentation of the Cambrian
deposits, sedimentation (connate) sea water deposits were formed simultaneously in
them
The geological history of the area during the Ordovician period is not well
understood; however, many authors believe that the marine regime continued
throughout this time (e.g.,Amin, 1961;Said,1962).
Silurian deposits are not recorded in the area of the Libyan Desert.Accordingly,it
is believed that by the end of Ordovician times an epierogenic uplift of the land
occurred in the northern part of the African Continent. Consequently,by these times
the sedimentation period ended and an infiltration period commenced which extended
till the end of the Devonian period. During this time the area of the Nubian Artesian
Basin developed in continental conditions and was subjected to continuous washing
and freshening of the water-bearing formations,replacement of the sea water by fresh
meteoric water, and displacement of the highly saline ground water seawards.
(ii) The beginning of the second major hydrogeological cycle can be assigned to the
end of the Devonian and beginning of the Carboniferous periods when a widespread
transgression of the sea occurred owing to the sinking of the land surface in the
northern part of the Libyan Desert (e.g. Ball, 1939; Amin, 1961;Said, 1962).
Transgression of the sea attained its maximum extent in Middle Carboniferous times,
when the shore line probably reached the latitude of Bahariya Oasis. During this
384
The Nubian Arfesiart Basin -regional Jtydrogeologicd aspects
period and up till the end of Carboniferoustimes there was a dominance of processes
of replacement of fresh already-infiltratedwater in the pre-existingsediments by sea
water,and deposition of saline connate sea water in the newly formed Carboniferous
sediments.
At the end of the Carboniferous period an extensive uplift of the land in the
northern part of the Libyan Desert is recofded. Consequently, all the area now
occupied by the Nubian Artesian Basin was again subjected to continental
environments from the beginning of the Permian period up till the end of the Triassic
period when the water-bearing formations were washed and freshened by the fresh
infiltration water, and the saline and highly saline water was displaced to the north.
Geological data indicate that at this period there still existed a marine gulf in the
south-easternlocalities of the Libyan Desert area.
At the beginning of the Mesozoic era, sea transgression is recorded only ín the Sinai
Peninsula and probably in the northernmost part of the Libyan Desert (Amin,1961),
while the whole of the remainder of the artesian basin developed in continental
environments.
(iii) The first major Mesozoic hydrogeological cycle can be assigned to the end of
the Triassic and beginning of the Jurassic periods when the land surface in the
northern regions of the Libyan Desert suffered downwarping, resulting in the
occurrence of sea transgression from north to south in the form of two great gulfs
(Amin, 1961). The sea transgression attained its maximum extent during the middle of
the Jurassic period when the shore line reached latitude 29" north of Siwa Oasis. By
the beginning of this transgression another period of sedimentation was initiated in
this northern part of the Nubian Artesian Basin. However,by the end of Jurassic times
and the beginning of the Early Cretaceous period the greater part of the Libyan Desert
was again subjected to continental conditions. During this time a short infiltration
period occurred, when the water-bearingformations of Jurassic and pre-Jurassicages
were subjected to processes of washing, replacement of saline sea water by fresh
infiltration water, and displacement of the highly saline water and brines to the north.
On the other hand, palaeolithological studies indicate that a great part of the
continental deposits of the Nubian Series was deposited particularly during this period
(Amin,1961;Said,1962).
B. The second and most important stage in the history of the Nubian Artesian Basin
extends from the middle of the Early Cretaceous up to the end of the Pliocene period.
During the middle of the Early Cretaceous is recorded the beginning of the most
intensive and widespread transgression of the sea on the northern part of the African
Continent, taking place from north to south as a result of an extensive progressive
lowering of the land surface. By the end of the Lower Cretaceous period, all the
regions of the North African Continent were submerged under sea. Transgression of
the sea at the end of the Cretaceous period and the beginning of Palaeogene probably
reached the southern regions of Egypt and the northern regions of Sudan (e.g., Ball,
1939).
The advent of the sea on the continent during the above-mentioned period initiated
the most extensive and prolonged hydrogeological cycle in the whole geological
history of the region. Water-bearinghorizons of the Nubian Series containing,in most
localities,fresh infiltration water were subjected to contamination and replacement of
their ground water by saline sea water. On the other hand,connate sea water was being
formed in the nearly deposited Upper Cretaceous sediments and the younger ones.
In the southernmost regions of the area now occupied by the Nubian Artesian Basin
continental environments were retained,with infiltration of fresh meteoric water in
385
I. II. Himida
the formation of the Nubian Series exposed in these regions.
. At the end of Palaeocene times the sea had begun lo retreat northwards,and by
that time an extensive and prolonged period of infiltration had started.At this time
also,the Nubian Artesian Basin began to acquire its aspects and configuration.
Steps in the development of the Nubian Artesian Basin from the beginning of the
Eocene period up till the present time are illustrated in a series of schematic palaeohydrogeological maps (Fig.4).
Sed rekression during Early Eocene times reached the southern regions of Farafra
Oasis. However, in the eastern and western regions of the artesian basin a marine
regime continued because of the presence of two great gulfs (Fig.4a).
The boundary line between the zones of highly saline water and brines and that of
brackish water most probably extended into the sea zone,not far from the shore line,
as a result.ofthe relatively high hydraulic gradient of the ground water caused by the
sinking of the northern part of the artesian basin.
The main catchment areas of the Nubian Artesian Basin at this time were located
on the south-westernhighlands as well as the southern and south-easternregions of the
artesian basin. At the same time, rainfall on the extensive area of the artesian basin
probably played rhe main role in the processes of washing the water-bearing
formations, freshening their ground water and displacing the highly saline water and
brines to the north.
At the end of Eocene times and the beginning of the'Oligocene period an intensive
uplifting of the land in the northern regions of the Nubian Artesian Basin area was
recorded. As a result,the sea receded and an extensive area of the artesian basin was
.developedin continental environments.At that time the shore line probably reached
the latitude of Fayum (Ball, 1939;Said, 1962). Consequently,during this period the
infiltration processes continued, taking place also in the land areas previously covered
by the Ebcene sea.
A cycle of mountain formation took place at this time along the eastern boundaries
of the Nubian Artesian Basin,with the resulting formation of high mountain ranges in
the region now'.coveredby the Red Sea.These mountain ranges most probably played
an active role as catchment areas of the artesian basin besides the other areas
mentioned above (Fig.4b).
At the beginning of the Miocene period, in the northern regions of the Libyan
Desert, a more or less stable regime was recorded,with a tendency of slight subsidence
and,limited sea ,transgressionsouthwards,On the greater part of the artesian basin area
continental environments were still dominating, with the continuation of the
infiltration processes (Fig.4c).
At the end of the Miocene period the general sinking of the land appears to have
ceased and been followed by upward movement,with the regression of the sea to the
north:.These movements were accompanied in the eastern part of the country by an
intensive cycle of tectonism which resulted in the uplifting of the whole region of the
Sinai Peninsula above sea level and the formation of different systems of faulting and
folding,especially in the northern regions of the artesian basin area. The beginning of
formation of the Nile Basin is assigned to this period (Ball,1939;Said, 1962). At this
time most of the territory now occupied by the Nubian Artesian Basin was subjected
to continental conditions for a long period (Fig. 4d).
Starting from the beginning of the Pliocene period, there commenced a great
tendency of land to sink in the northern regions of the Nubian Artesian Basin area,
resulting in the gradual raising of the sea level, which attained a level about 180 m
higher than.its present level,.The shore line,at this time,retreated until it reached the
latitude of Cairo and Wadi El-Natrun.However, in the Nile Basin, land subsidence
386
seems to be much more intensive. The intensive land subsidence in the Nile Valley
resulted in the intrusion of the sea southwards in this last area in thc form of an
elongated gulfwhich probably reached the southern regions of Egypt and the northern
localities of Sudan when the transgression of the sea attained its maximum extent by
the Middle Pliocene period.
Ingression of the sea water in the Nile Valley, obviously, resulted in the
contamination of the water-bearinghorizons of the pre-Pliocenesediments with saline
sea water and,at the same time,in the formation of connate sea water in the newly
deposited Pliocene sediments in the Nile Valley and in some of the northernmost
localities of the artesian basin area.
In the later part of the Pliocene period the land subsidence ceased and was followed
by intensive upward movement accompanied by intense folding and faulting in the
eastern part of the artesian basin. As a result of these tectonic movements the
mountain ranges of Sinai and of the Eastern Desert were thrust to much higher levels
than before.
The presence of a large number of dry valleys filled with Pliocene and Pleistocene
deposits in the Eastern Desert having a general orientation from east to west, in
addition to the palaeoclimatic data, indicates that the artesian basin had by this time
been receiving intensive recharge from the eastern regions (Fig. 4e).
C. The third stage in the evolutionary history of the Nubian Artesian Basin begins
from the end of the Pliocene period and extends up till the present time.At the end of
Pliocene times all the territory of the Nubian Artesian Basin was developed in
continental conditions not differing much from the present prevailing conditions.
However,by these times, the amount of rainfall was probably much higher,especially
in the areas of high altitudes. At this time, on the other hand, the depressions of
Kharga and Dakhla Oases were already formed. It can be concluded that the other
depressions of the Libyan Desert were also formed.
Since the end of the Pliocene period, no transgressions of the sea are recorded on
the area of the Nubian Artesian Basin.
Considering the present prevailing hydrogeological aspects of the Nubian Artesian
Basin and its evolutionary history,as described above, the following conclusions can
be stated:
1) The occurrence of considerably thick water-bearingformations containing highly
saline water and brines in the northern regions of the Nubian Artesian Basin can be
explained by the fact that these formations were mainly deposited in marine
environmentsand that they have been submerged under the sea numerous limes during
the long period of their geological history,where they were subjected to sedimentation
processes.
2) The occurrence of extensive water-bearing formations containing fresh water in
the central and southern regions of the artesian basin can be explained by the fact that
these areas were mainly developed in continental environments where they have long
been subjected to processes of infiltration of fresh meteoric water in the water-bearing
formations, of washing and of displacement of any original sea water. On the other
hand, these regions were developed in a marine environment for a relatively short
period;the southernmost regions of the artesian basin have been developed entirely in
continentalconditions.
3) The noticeable lowering of ground-watermineralization in the water-bearing
horizons of the Nubian Series relative to that of the Post-Nubian water-bearing
horizons in the same locality can be attributed to the evolutionary history of both
water-bearing complexes. Nubian water-bearing formations in most localities were
3 87
I. H.Himida
originally deposited in continental or shallow-waterconditions and for a long time
were subjected to washing processes by fresh infiltration meteoric water. On the other
hand, the water-bearing formations of the Post-Nubian complex were originally
deposited in marine environments where simultaneously connate sea water was formed
in it, and later on,after their formation,they were repeatedly covered by sea water.
4) Reversed zonation in salinity of the ground water in the regions of Kharga,
Dakhla, Farafra, Bahariya Oases, etc., can be also explained on the basis of the
palaeohydrogeological studies of the artesian basin. The widespread transgression of
the sea from north to south in Middle Cretaceous times covered an extensive area in
the central part of the artesian basin that previously developed in continental
environments. Accordingly, the pre-existingfreshwater horizons in these regions were
contaminated by saline sea water. Obviously,contamination by saline sea water was
most pronounced in the uppermost water-bearing horizons and gradually decreased
downwards. So, in such regions it is normally expected that even after a long period of
washing, the ground-watermineralization of the upper water-bearing horizons should
be higher than that in the lower water-bearinghorizons.
REFERENCES
AMIN, M.S. 1960: The Nubian sandstone aquifer and its bearing on the oil possibilities of the
Western Desert.Second Arah Petroleum Congress,Beirut.
AMIN,M.S. 1961: Subsurface features and oil prospects of the Western Desert, Egypt,U.A.R.
Third Arab Petroleum Congress,Alexandria.
ANDREW, W.G.1937: On the Nubian sandstone of the Eastern Desert of Egypt. Bttll. Inst.
Egypte.
ATTIA,M.I.1954:Ground water of Egypt.Bull. de I’Inst. du Desert d’Egypt.Jan. issue.
BALL,J. 1900:Kharga Oasis,Its Topography and Geology. Survey Dept,Cairo.
BALL,J. 1909:On the origin of the Nile Valley and the Gulf of Suez. Cairo ScientificJournal.
BALL,J. 1927:Problems of the Libyan Desert: the artesian water suppliesof the Libyan Desert.
Geogr. Jour. 70.
BALL,J. 1939:Contributions to the Geogruphy of Egypt. Survey Dept,Cairo.
BALL,J.; BEADNELL,H.J.L.1903: Bahariya Oasis, Its Topography arid Geology. Survey Dcpt,
Cairo.
BEADNELL,H.J.L.1901a:Dakhla Oasis,Its Topography arid Geology. Survey Dept,Cairo.
EEADNELL,H.J.L. 1901b:Farafku Oasis,Its Topography and Geology. Survey Dept,Cairo.
I3tADNELL,H.J.L. 1905: The Topogruphy and Geology of Ihe Fayouin Province of Egypt.
Survey Dept,Cairo.
BEADNELL,H.J.L.1908:Plowing wclls and subsurfacewaters in Kharga Oasis.Geol. Mag.
BEADNELL,H.J.L. 1909:A n Egyptian Oasis. A n Account of the Oasis of Kharga in the Libyan
Desert. London.
CATON-THOMPSON,G.;GARDNER, E.W. 1934:The prehistoric geography of Kharga Oasis.
Geogr.Jour. 80.
DROUHIN,G. 1952: The problem of the water resources in North-WestAfrica. UNESCO Review
of Research on Arid ZonesHydrology. UNESCO,Paris.
GARDNER, E.W. 1932a: Some problems of the Pleistocene hydrography of the Kharga Oasis.
Geol. Mag.
GARDNER,E.W.1932b:The Pleistocene fauna and flora of Kharga Oasis. Geogr. Jour.
GREGORY,J.W.191:The African rift valley. Geogr. Jour. 56.
388
The Nubian Artesian Basin
-regional hydrogeologicalaspects
GREGORY, J.W.1921: The Rift Valley and Geology of East Africa and Relations to the
Contemporary Earth Movements which Transform the Geology of the World. Seeby Service,
London.
GODJIEV,A.A.1957a:Kvatkia Istoriya VozniknoveniyaAfrikanskova KOntiJlenta,Razvietiya evo
Prirody. OTSHPEDGIZDAT,Moscow.
GODJIEV,A.A. 1957b:Relief i Geologicheskiye Stroeniya Afiiky. OTSHPEDGIZDAT,Moscow.
HASSANEIN,A.M. 1924:Through the Kufra to Darfur. Geogr.Jour. 64.
HELLSTROM, B. 1940: The subterranean water in the Libyan Desert. Bull. No. 26,Inst.
Hydraulics Roy. Stockholm
HIMIDA,I.H. 1963: Geologicheskye stroeniya liveskey postieny v. O.A.R. Izv. Vish. Otshepnikh
Zaved.,Geologiya i Razviedka No. 9.MGRI,Moscow.
HIMIDA,I.H.1965:Artezianskiye vody Nubskikh pishanikov v liveskoy postiene O A R .Izv. Vish.
Otshepnikh Zaved.,Geologiya i Razviedka No. 6.MGRI,Moscow.
HIMIDA,1.H.1966:A quantitative study of artesian water exploitation resources in Kharga and
Dakhh Oases,Western Desert,U.A.R.Bull,Desert Inst. I6 (2). (issued Dec. 1968.)
HIMIDA,I.H.1967: Remarks on the absolute age determination of the artesian water of the oases
of the Western Desert with special reference to Kharga Oasis.Bull. Desert Insf. I7 (2). (issued
Dec. 1969.)
HUME,W.F.1910:The origin of the Nile Valley in Egypt.Geol.Mag. 7. (decade 5.)
HUZAYYIN,C.A. 1940: The Place of Egypt in Prehistory:A Correlated Study of Climates and
Cultures in the Old World. Cairo.
IBRAHIM,M.M. 1956:The origin of the depressions in the Libyan Desert. Obs.Proc. Geol. Soc.
Egypt 2.
IBRAHIM,M.M. 1959: Discussion on the Form of the Precambrian Basement Underlying the
Nubian Sandstone,An Aquifer of the WesternDesert. Cairo.
KAMENSKY, G.N. 19?: Voprosy formirovaniya podzemhykh vod. Trudy Lab. Gìdrogeologicheskhikh Problemy 16.Moscow.
KARTSOV, A.A.; VAGIN, C.B. 1960: Printsipy i poty palaeogidrogeologichesikh issledovany.
Problemy Gidrogeology.GOSGEOLTEKHIZDAT,Moscow,
KRENKEL,E. 1924:Der Syriche Bogen. Col.Min.
KUDELIN, B.I. 1959: K. voprosso o palaeogidrogeologicheskikh osloviyakh vod drevnavoska
dontskom artezianskom baciene.Sovetskya GeologiyaNo. I O. Moscow.
LITTLE, O.H.;ATTIA, M.I. 1942: The Deep Bores in Kharga and Dakhla Oases.Geol.Survey
Dept,Cairo.
MAVRITSKY,B.F. 1957:IrtishkyArteziansky Bacien. Fund MGRI,Moscow.
MAVRITSKY,B.F. 1960: Kratkiya palaeogidrogeologicheskiya kharakteristika zabadna sibirskova
artezianskova baciena.Problemy Gidrogeology. GOSGEOLTEKHIZDAT,Moscow.
MITWALLY,M. 1953: Physiographic features of the oases of the Libyan Desert.BuII. Inst.Desert
d 'Egypte3 (2).
MURRAY, G.W.1952:The artesian waters of Egypt.Min. of Fin. Econ. Surv. Dept PaperNo. 52.
Cairo.
OMARA, S.; HIMIDA, I.H.;SANAD, S. 1970: Structure and hydrogeology of Farafra Oasis,
Western Desert,U.A.R.SeventhArab Petroleurn Congress,Kuwait.
OVICHINNIKOV,A.M. 1955:Obshaya Gidrogeologiya. GOSGEOLTEKHIZDAT,Moscow.
PAVER,G.L.;PRETORIUS,D.A.1953:Report of hydrogeological investigations in Kharga and
Dakhla Oases.Bull. No. 4,Deserthzst. Egypt. Cairo.
PAVLOV,M.I.;BURDON,D.I.1959a:Investigation and exploitation of ground water for Kharga
and Dakhla Oases.Bull. Prelim Rep. to Gen. Des. Dev.Author. U.A.R.,Cairo.
PAVLOV, M.I.;BURDON, D.I. 1959b:Ground water of the Kharga Oasis as a source of the
reclaim.ofnewland.Rep. to Gen.Des.Dev.Author. U.A.R.,
Cairo.
SAID,R. 1962: Geology of Egypt,Elsevier,Amsterdam-NewYork.
389
F.Slepirka
SANDFORD, K.S. 1932: Geology and Geomorphology of the southern Libyan Desert, Geogr.
Journ. 82.
SANDFORD, K.S. 1953: Geological observations on the NW frontier of the Anglo-Egyptian
Sudan. Q.J.G.S.,London.
SHATA,A. 1953: N c w light on the structural development of the Western Desert of Egypt.Bull
Des. Inst. 1. Cairo.
SHATA, A. 1955: An introductory note on the geology of the northern portion of the Western
Desert.Bull. Des. Inst.2. Cairo.
ANALYTICAL RELATIONS IN THE TIME FREQUENCY OF THE
TOTAL, RIVER RUNOFR AND ITS GENETIC COMPONENTS
F.SLEPICKA
Water Research Instituie,Prague,Czechoslovakia.
SUMMARY
One of the partial problems in the hydrological balance of the time runoff regime,which is solved
in the representative watershed of the Czech Cretaceousmassif,is described here.
Starting from the already investigated principle of correspondenceof m-daily river runoffvalues
and m-daily ground-water excesses, which contribute to the total runoff, the law of relation
between both values is derived. Having the shape of a power function it is expressed in the
bilogarithmic functional net as a straightline with three sections. Each of these sections is valid for
one of the specific,temporally limited water resources of watercourses. It is possible to carry out
the solution for one hydrological year and other, even longer periods (decade,geohydrological
period, long-term periods). This way the new analytical formulation method of relations in the
time frequency of genetic runoff components and of the total runoff becomes a means which
enables, besides other things, the division of ground-water excesses of various origin, the
determination of their values and safeguarding in the considered period. It enables also other
information concerning ground water, circumstances important for more precise planning and the
perspective hydro-economical balances, their exploitation with regard to other interests of the
national economy and their artificialenriching.
RÉSIJML
RAPPORTS ANALYTIQUES ENTRE LA FREQUENCE TEMPORELLE D E
L’ECOULEMENT FLUVIAL TOTAL ET SES COMPOSANTES
O n trouve dans cette étude une description de la manière dont l’un des problèmes partiels
que pose l’établissement du bilan hydrologique du régime temporel de l’écoulement a été
résolu pour le bassin représentatif d u massif crétacé tchèque.
Partant du principe déja étudié de la correspondance entre m valeurs de l’écoulement
fluvial quotidien et m vdeurs des excédents quotidiens d’eaux souterraines qui contribuent
à l’écoulemcnttotal, on a déduit la loi régissant la relation entre ces deux séries de valeurs.
C’estune fonction exponentielle représentée en coordonnées bilogarithmiques par une droite
comporlant trois scgments. Chacune de ces sections est valable pour l’undes apports d’zau
spécifiques et .-mporellementlimités que recoivent les cours d’eau.11 est possible d’appliquer
ccttc méthode pour une année hydrologique et m ê m e pour des périodes plus longues
(décennie. période géohydrologique, longue durée). Cette nouvelle mûnière de formuler
analytiquemcnt les relations entre la fréquence temporelle des composantes de l’écoulement
3 90