Hydrology and Water Resources of Africa (Water Science and Technology Library)

686 Pages·2002·62.68 MB·English

by  M. Shahin

HYDROLOGY AND WATER RESOURCES OF AFRICA
Water Science and Technology Library
VOLUME 41
Editor-in-Chief
V. P. Singh, Louisiana State University, Baton Rouge, U.S.A.
Editorial Advisory Board
M. Anderson, Bristol, U.K.
L. Bengtsson, Lund, Sweden
J. F. Cruise, Huntsville, U.S.A.
U. C. Kothyari, Roorkee, India
S.E. Serrano, Lexington, U.S.A.
D. Stephenson, Johannesburg, South Africa
W.G. Strupczewski, Warsaw, Poland
The titles published in this series are listed at the end of this volume.
HYDROLOGY AND
WATER RESOURCES OF AFRICA
by
MAMDOUH SHAHIN
Water Resources Engineering Consultant
Formerly Professor Cairo University, Giza, Egypt
and
IHE-Delft, The Netherlands
KLUWER ACADEMIC PUBLISHERS
NEW YORK,BOSTON, DORDRECHT, LONDON, MOSCOW
CD-ROM only available in print edition
eBookISBN: 0-306-48065-4
Print ISBN: 1-4020-0866-X
©2003 Kluwer Academic Publishers
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AFRICA
To:
A Continent Rich in Development Potential
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PREFACE
Africa, the cradle of many old civilizations, is the second largest world
continent, and the homeland of nearly one-eighth of the world population.
Despite Africa’s richness in natural resources, the average income per person,
after excluding a few countries, is the lowest all over the world, and the
percentage of inhabitants infected with contagious diseases is the highest.
Development of Africa to help accommodate the ever-increasing population
and secure a reasonable living standard to all inhabitants, though an enormous
challenge is extremely necessary. Water is the artery of life, without it all living
creatures on earth cannot survive. As such, a thorough knowledge of the
meteorological and hydrological processes influencing the yield and quality of
the water resources, surface and subsurface, and their distribution and variability
in time and space is unavoidable for the overall development of any part of the
world. It is highly probable that the said knowledge is at present a top priority to
Africa, a continent that has been for so long-and probably still-devastated by the
endless ambitions of colonial powers not to forget the corruption and destruction
practiced by the internal powers, at least in some countries.
The present book “Hydrology and Water Resources of Africa” is written
with the aim of bringing together in one volume a fair amount of knowledge any
professional involved in hydrology and water resources of Africa needs to know.
African hydrology, after all, covers a wide range of subdivisions ranging from
Hyper-arid and arid (Saharan) to very humid (Tropical). With this aim in mind,
the material covering the book is distributed among fourteen chapters. The first
chapter, as usual, serves as a general introduction. The second, third, fourth and
fifth chapters outline and discuss the basic items relevant to climate such as
precipitation, evaporation and evapotranspiration. These four chapters are
presented from the angle of applied climatology rather than theoretical
meteorology.
Chapter 6 deals with the processes of runoff and streamflow. Such processes
combined with the contents of Chapters 2 to 5 help elaborate a reasonable
estimate of the water balance of each of the main hydrologic sub-systems of the
continent. Chapters 7 and 8 deal with hydrology of large river basins in East and
West Africa, and Central and Southern Africa respectively. Certain aspects of
hydrological interest concerning intermediate and small river basins, including
ephemeral streams (wadis), are outlined and discussed in Chapter 9.
The built-up of Africa includes some areas of wetlands in the form of
permanent and seasonal swamps, marshes, and floodplains. The Great Rift
Valleys already formed as a result of the tectonic movements and volcanic
activities during the Miocene era have created depressions and lakes of depths
up to 1,000 m. The volumes of the African Lakes are about eleven times as
vii
viii PREFACE
much as the annual volume of river flows. No wonder then that the world of
Tropical Africa is not dominated by its rivers but rather by its lakes. The
principal hydrologic, morphometric and physico-chemical parameters, and the
mass balance of several of the wetlands including natural lakes are dealt with in
Chapter 10.
Due to the geographic location of Africa, thereupon its climate, the flow of
many an African river is highly seasonal. To satisfy the demand on water, the
natural supply of several rivers is regulated through storage reservoirs created by
the dams built across these rivers. A description of some of the large African
dams, their dimensions, functions and the relevant particulars underlying the
design of their respective reservoir storage capacities are given in Chapter 11.
The African ground is underlain by groundwater reservoirs some of which
have huge dimensions and storage volumes. Classification of these reservoirs
according to their geology, and estimates of the hydrogeological parameters of
the water-bearing formations and their productive aquifers are given in Chapter
12. Of particular interest are the types of aquifers encountered, rates and means
with which aquifers are being recharged. The comparison between the rates of
recharge to and extraction from an aquifer serves as a criterion for distinguishing
between rejuvenated and non-rejuvenated or fossil water. The quality of
groundwater and its suitability for drinking and domestic purposes too are
reviewed. The survey and analysis presented in Chapter 12 cover a rather large
number of areas of Africa.
Africa consists of a main or fast land and a number of sets or groups of
islands. Despite the fact that most of the islands are geographically located at a
large distance from the fast land, and are administered by European countries
such as France, Portugal, etc, yet in a way they are regarded as part of Africa.
With the exception of Madagascar, the fourth largest island of the world, all
African islands can be classified as small. Chapter 13 deals mainly with the
climate, hydrology and water resources of all African islands whether small or
large.
Chapter 14, the last chapter of the book, deals with the development of
Africa from the point of view of water resources. The present state of Africa, the
water resources development and management projects implemented in the 20th
century, and the possible future development and management of water
resources are presented. The effects of flow regulation and control works on land
irrigation, hydropower development, fisheries, and river navigation are
highlighted. Emphasis is laid on both the negative and positive aspects of water
sources and storage of water in reservoirs on vector water-related diseases. The
discussion is illustrated with a number of field surveys and case studies.
The presentation, analysis and discussion of the contents of the book would
not have been possible without using a wide range of data: basically
meteorological, hydrological, geohydrological and water quality data. Most, not
all, of the data used and the relevant sources of information are made available
PREFACE ix
to the user of the book on a compact disc (CD Rom) and the rest can be found in
the text itself. Classification of the data on the disc is described in the few pages
at the end of Chapter 14. It is unfortunate that most of the available data can be
fairly described as inadequate, both in quantity and quality. Furthermore, some
of the data that used to be continuously recorded or periodically collected are
already suffering for sometime from gaps of different widths, and some of them
even stopped. The authorities concerned are strongly advised to pay considerable
attention, and secure the necessary means for data collection, dissemination and
processing.
The preparation of the book contents has certainly required considerable
effort and long time. A large number of books, research papers, technical
bulletins, reports and documents, all added to the author’s professional
experience in certain parts of Africa, were assembled, reviewed and worked out.
As the book publication is now in sight the author wishes to express his heart-
felt thanks to all who have contributed in a way or another to bring it to almost
completion. It is impossible to mention the name of each one of them. However,
a few names have to be mentioned in recognition of their unforgettable and
undeniable services. The author is grateful to Professor V.P. Singh for
recommending to Kluwer Academic Publishers, The Netherlands, to consider
the publication of the book. Thanks are also due to the staff of the libraries of
water resources divisions in many of the World Organizations and Universities.
Mrs. P. Franken and the staff of the library of the IHE, Delft, The Netherlands,
deserve special mention. Thanks are extended to Mr. Z. Salty and Mr. A.
Botrous for their unfailing assistance to solve computer-related problems. Last,
but not least, the author is grateful to the publisher for the encouragement as well
as useful suggestions to improve the manuscript.
Mamdouh Shahin March2002
Voorburg, The Netherlands