The River Nile. Geology, Hydrology and Utilization

316 Pages·1993·10.467 MB·English

by  R. Said (Auth.)

Related Pergamon Titles of Interest
BOOKS
CLOUDSLEY-THOMPSON: Key Environments: Sahara Desert
EDWARDS & HEAD: Key Environments: Red Sea
GORE: International Order, Economic Regionalism and Structural Adjustment:
The Case of Sub-Saharan Africa
MARTINEZ & HARBAUGH: Simulating Nearshore Environments
MENZIES: Glacial Environments: Processes, Sediments and Landforms
OPEN UNIVERSITY: Waves, Tides and Shallow-Water Processes
JOURNALS
Continental Shelf Research
Journal of African Earth Sciences
Quaternary International
Quaternary Science Reviews
Water Research
Water Science and Technology
Full details of all Pergamon publications/free sample copy of most Pergamon journals
available on request from your nearest Pergamon office.
THE RIVER NILE
Geology, Hydrology and Utilization
RUSHDI SAID
Consulting Geologist, Ph.D. (Harvard),
Dr. rer. not. h.c. (Technical University, Berlin),
Membre Institut d'Egypte, Honorary Fellow Geological Society of America,
Honorary Member Geological Society of Africa
PERGAMON PRESS
OXFORD · NEW YORK · SEOUL · TOKYO
U.K. Pergamon Press Ltd, Headington Hill Hall,
Oxford OX3 OBW, England
U.S.A. Pergamon Press Inc. 660 White Plains Road,
Tarrytown, New York 10591-5153, U.S.A.
KOREA Pergamon Press Korea, KPO Box 315, Seoul 110-603,
Korea
JAPAN Pergamon Press Japan, Tsunashima Building Annex,
3-20-12 Yushima, Bunkyo-ku, Tokyo 113, Japan
Copyright © 1993 R. Said
All rights Reserved No part of this publication may be reproduced,
stored in a retrieval system or transmitted in any form or by any
means: electronic, electrostatic, magnetic tape, mechanical,
photocopying, recording or otherwise, without permission in writing
from the publisher.
First edition 1993
Library of Congress Cataloging in Publication Data
Said, Rushdi
The river Nile: geology, hydrology, and utilization / Rushdi Said,
p. cm. Includes bibliographical references.
1. Nile River. I. Title.
GB 1361.S25 1994 551.48'3O962-dc20 93-28862
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the
British Library
ISBN 0 08 041886 4
Cover: Inji Efflatoun 1985: The Nile at Deir el-Adra
oil on canvas 35 χ 80cm
Printed in Great Britain by BPCC Wheatons Ltd, Exeter
Dedicated to Professor Eberhardt Klitzsch
on the occasion of his sixtieth birthday
PREFACE
This book is the result of many years of research. It is an attempt to reconstruct the history of
the river Nile from its origins to its present shape and regimen. It is also an attempt to ascertain
the amount of water which was carried by the river during the course of its history, the manner
in which this water was utilized in the past and the manner in which it has to be utilized in the
future if the inhabitants of the river basin are to cope with their increased needs.
Although this book has for its subject the entire Nile Valley, the reader will find that the
Egyptian part of the Nile has been treated at greater length. There are many reasons for this
emphasis. In the first place, the Egyptian Nile is one of the best known parts of the river; it has
been the subject of numerous studies by multidisciplinary groups during the past three decades.
It has also been penetrated by a large number of boreholes some of which have reached the oldest
of its sediments offering an almost complete and uninterrupted record of its history. Furthermore,
the Nile in Egypt lies in the downstream part of the river whose regimen and sediments are
affected by events in the upstream part and can tell us, therefore, a great deal about changes and
developments occurring there.
There is a fascination about the Nile which has captured people's imagination throughout
history. Nowhere has this fascination been greater and longer lasting than with the Egyptian end
of the river. Here emerged a great civilization some five thousand years ago which depended
entirely on the river and its annual inundation. Yet the secret of this inundation and the sources
of this great river remained a mystery for this literate, vigorous and highly organized society.
For a very long time after the demise of this civilization the question of the sources of the Nile
stirred the imagination of men; it became of cardinal concern to the world at large during the
nineteenth century when explorers finally resolved the mystery.
The Nile's beginnings, when it first appeared, and how it assumed its present shape and
regimen were other enigmatic and baffling questions which occupied the minds of men from
the earliest of times. Like the sources of the Nile, the beginnings of the river were also wrapped
in mystery and became the subject of legend. For most of the twentieth century the facts about
the early history of the river were unknown and, in the absence of these, even the scientists'
attempts to reconstruct the early history of the river were no more than speculations that
bordered on legend. The real breakthrough in this field occurred when the river's earliest
sediments became amenable to study. These sediments are deeply buried under the surface, and
were reached only lately by many of the deep boreholes drilled in the delta of the Nile by
companies exploring for oil. My consulting work exposed me to the wealth of data from these
boreholes which held the secrets of the river. Not only did these boreholes reach the oldest
sediments of the river but they also preserved a complete record of them. The task of
ix
χ Preface
reconstructing and interpreting the column of sediments of the river was facilitated and greatly
enhanced by another breakthrough resulting from the publication of a study of boreholes drilled
off the coast of the Nile delta in 1972 by the Deep Sea Drilling Project, an international effort
to study the bottom of the oceans. By correlating the delta boreholes with those of the Deep Sea
Drilling Project we were able to unfold the early history of the river and to show its tumultuous
evolution and tenuous connections with sub-Saharan Africa.
The later history of the river has been closely associated with man. Many questions awaited
an answer such as when man first appeared along the banks of the river and where did he come
from? Did the moods of the river influence his settlement patterns, and who were the men who
were responsible for that spectacular civilization that appeared on the banks of the lower parts
of the river some five thousand years ago? Little was known about the earlier settlers of the
valley until lately, for inspite of the fact that excellent studies had been made on some of their
sites since the beginning of the twentieth century, these studies were few and scattered. The real
breakthrough took place in the 1960's when systematic studies in the field of prehistory were
conducted along the banks of the Nile, as part of the international campaign launched to save
the monuments of Nubia which were about to drown beneath the waters of Lake Nasser, that
was forming as a result of the building of the Aswan High Dam. It was my good fortune to be
associated with this program of research conducted by an interdisciplinary team made up of a
core of archeologists. Although much remains to be done in this field, we now have at least a
credible concept of the history of the early settlement of the valley.
In addition to the chapters dealing with the historical aspects of the river, this book also
includes chapters which treat the present and future state of the river and the utilization of its
waters. The patterns of water utilization are determined by the amount of water carried by the
river, which fluctuates from year to year. For those of us who started their interest in the Nile
from a historic, if not a prehistoric, perspective, the present-day unprecedented small flows of
the river, caused by the drought that has been ravaging the Sahel region for the past two decades,
seem to be part of a natural phenomenon and seem likely to continue. The low rainfall in the
Sahel and the Ethiopian Highlands of recent years is further evidence of the phenomenon, which
we have documented during our studies in prehistory, whereby sequences of low Nile flows and
sequences of high Nile flows tend to follow each other. My concern about the impact of these
anticipated low flows on the rising demands of the inhabitants of the river is heightened by my
readings on the geological history of the river, which seem to point to an even less benevolent
Nile in the long run.
This book, therefore, is of interdisciplinary nature. It deals with many aspects of the Nile.
It is made up of four parts, and an appendix listing the references used and some of the pertinent
literature on the river. Because users of this book will have different backgrounds an effort has
been made, where possible, to present the scientific material included avoiding the use of
technical terms. Part I deals with the origin and evolution of the river. The story of the
developmentof the river until it assumed its present shape is truly fascinating. The subject matter
of this part is technical and I have tried to present it as simply as possible. However, for the
benefit of those readers who would find difficulty in following this account, a summary
outlining the story of the river in non-technical language is offered at the beginning of this part.
Part II deals with the hydrology of the river and the amount of water that the river and its
tributaries carry at present. It also attempts to ascertain the amount of water that the modern river
Preface xi
carried in the past from the time of its inception some 10,000 years ago. At that time great
climatic changes were taking place in the Nile Basin and wetter conditions prevailed over most
of the basin causing the river to carry greater amounts of water than today. These amounts
declined with the steady southward retreat of the rain front some 5000 years ago, leaving large
areas of the basin arid. Within that general trend, the flow of the river has fluctuated greatly
throughout its history.
Part III deals with the utilization of the waters of the Nile from the time of the first appearance
of man in the valley until the present time. It traces man's attempts to harness the river from the
earliest times to the time of the building of the High Dam at Aswan, which resulted in the full
control of the river and the conversion of its lower course into a man-made canal. After twenty
years of the operation of the dam, an attempt is made to evaluate its side effects.
Part IV deals with the present water supply-demand balance in each basin state and discusses
the future plans of these countries to use the waters of the Nile. Historically and until recently
Egypt was the sole user of the waters of the river. Rapidly growing populations and the frequent
and prolonged droughts of recent years are forcing many of the basin states to abandon rain
agriculture in favor of irrigated agriculture, and are thus demanding a share of the waters of the
river. This causes problems to all basin states not only with regard to the legal aspects of the
division of the waters of the river, but also with regard to the urgency of adopting efficient
methods for the use of the limited water resource. This part examines the status of the present
Nile Water Agreements among the basin states and shows that they fail to address the present-
day needs of these states.
With the exception of some conclusions and speculations, many of the facts bearing on the
wide variety of subjects dealt with in this book are extracted from works listed in the appendix.
The sections of the book which deal with topics outside my speciality were written after
discussions with specialists who kindly read my notes or added to my knowledge of the subject.
I owe them a word of thanks. Professor Klaus Fraedrich, Professor of Meteorology, Free
University of Berlin, read section eight (Part I) dealing with the climate. Engineer Naguib F.
Said, former under secretary of State, Egyptian Ministry of Irrigation, read the sections on the
irrigation works in Egypt and the Sudan. Professor John Waterbury, School of Public and
International Affairs, Princeton University kindly found time to read parts one and two of the
book. I owe my rudimentary knowledge of prehistory to Professor Fred Wendorf, Southern
Methodist University, who led the Combined Prehistoric Expedition in Egypt when it worked
closely with the Geological Survey of Egypt which I headed until 1978.1 also owe a word of
thanks to Professor D. Wildung and Dr Karla Kroeper, Berlin Egyptological Museum for
allowing me the free use of their excellent library and for drawing my attention to pertinent
literature. Dr Kroeper corrected the locations and spelling of some of the ancient sites which
appear on the map of the delta (Fig. 1.30). Thanks are also owed to Professor M. Kassas, Cairo
University, for supplying me with material regarding the quality of the water of the Nile; to Dr
A. el-Gazzar, agricultural attache of the Egyptian Embassy, Washington for the agricultural
statistics included in the book; to Engineer Abdel Hadi Radi, under secretary of state for the
Egyptian Ministry of Irrigation, for fruitful discussions and for making available to me the
Journal of Water Science which he edits and which includes useful summaries of the work
carried out by the different research institutes of the Ministry; and to Dr Abdel-Aziz Sadek, head
of the Documentation Center, Egyptian Antiquities Authority, for supplying me with practically
xii Preface
all the photographs of ancient Egypt (Figs 2.13,2.14,2.18,2.21,3.9,3.11,3.12,3.20 and 3.21).
Thanks are also due to Amoco Egypt for defraying part of the cost of the drafting of the figures
of the book.
I owe a special word of thanks to my wife Wadad not only for enduring the inconveniences
incidental to the writing of this book but also for reading the many versions of its manuscript.
This book could not have been written had I not been invited to spend the academic year
1989/90 as a fellow at the Institute for Advanced Study in Berlin (Wissenschaftskolleg). This
year allowed me to free myself from my busy schedule and to devote my entire time to
organizing field notes and information which I had amassed over the years on the River Nile and
synthesizing them into a whole. I owe a special word of gratitude to Professor Wolf Lepenies,
the dean of the Institute, for his gracious hospitality and for the genial and research-conducive
atmosphere of the Institute, which allowed me to finish this work. I also owe a debt to Professor
E. Klitzsch, Technical University of Berlin, for his continuous support. To him this book is
dedicated.
Washington, D.C.,
October 1992.
SUMMARY OF PART I
Part I deals with the geological history of the Nile river from the time it started to excavate its
valley some six million years ago. This summary is intended for the general reader and is written
in non technical language. The history of the river as outlined in this summary is given without
going into details or discussing the nature of the evidence from which this history has been
construed. The reader must recognize that geologic events which shape the features of the earth
such as the tilting of mountains, the formation of rift valleys, the advance and retreat of ice and
the rise and fall of sea level do not happen abruptly but take place over thousands if not millions
of years. The reader must also remember that with the exception of the recent dates (40,000 years
and younger) all other dates are very approximate and relative. The older dates are estimates
based on the position of the event relative to another event which is better dated.
The shape of the Nile we know today is a very recent development; it is but the last stage of
a continuously evolving river which changed its face many times before it assumed its present
look. The present-day river is complex, and is the result of the interconnection of several
independent basins by rivers which developed during the last wet period which affected Africa
after the retreat of the ice of the last glacial age some 10,000 years ago; the modern Nile is. indeed
the child of that wet phase. Prior to this, the basins which constitute part of the present river were
disconnected, forming internal lakes. At times when the climate was wet they overflowed their
banks and became connected to other basins; at other times when the climate was dry they ebbed,
shrank into saline pools or dried altogether. Figures 1.3 and 1.4 show the position and extent of
these basins of the Nile today. The basins stand out in the longitudinal section of the river
(Fig. 1.4) as flat stretches or landings with very little slope, which are connected today with
rivers which have considerably steeper slopes.
In the Equatorial Plateau lie the basins of lakes Victoria, Kioga and Albert which slope gently
toward the north at an average rate of one meter for every 20 to 50 kilometers of stretch. In
contrast the swift rivers which connect these lakes fall at an average rate of one meter for every
kilometer or less of length. To the north of these lakes lie the enormous Sudd and Central Sudan
basins which extend for a distance of 1800 kilometers from Juba to Khartoum, and which form
a gently sloping region with the phenomenally small rate of slope of one meter for every
24 kilometers of stretch. The river which connects this basin with Egypt is the swift Nubian Nile
with its rapids and cataracts; it falls at the rate of one meter for every six kilometers of stretch.
The past six million years which witnessed the making of the Nile were characterized by
major climatic fluctuations that affected the entire globe. The polar ice sheets and mountain
glaciers advanced and retreated many times during this period. These were accompanied by
great fluctuations in temperature, atmospheric pressure gradients, rainfall patterns and sea level
1
2 The River Nile
— all of which left their impact on the history of the Nile. In addition, the past six million years
witnessed great earth movements and volcanic activity that affected in particular the area of the
headwaters of the Nile. The reactivation of the great African Rift Valley (Fig. 1.6) tilted
mountains and redirected the drainage of both the Equatorial and Ethiopian Highlands toward
the Nile. Previous to these movements most of the drainage of these plateaus had been directed
to the Congo basin and to the Red Sea and the Indian Ocean respectively. Effective also in
determining the course of the tributaries that came from these plateaus was the spewed volcanic
material that spilled over the surface of these plateaus in great quantities during the years of
formation of the river; it blocked the way of many of the tributaries forcing them into new
courses and determining their paths.
Figure 1.1 (top) is an attempt to reconstruct the shape of the basin of the Nile before the
African rift had taken its present shape and at the time the Egyptian river started to excavate its
channel some six million years ago. The Red Sea was then a small longitudinal trough and the
Equatorial Plateau was high and without lakes. Most of the drainage of the Equatorial Plateau
was directed toward the Congo basin or the Indian Ocean, but part went northward toward the
great Sudd lake which occupied a large part of the modern Nile Basin. Egypt was separated from
sub-Saharan Africa by the high Nubian massif, and the new Egyptian river that was forming was
not connected with Africa. Figure 1.1 (bottom) attempts to reconstruct the Nile Basin some five
million years later after the great African rift had taken its modern shape. The Equatorial Plateau
was cut across by two rift systems, a western rift which was filled with lakes Tanganyika, Kivu,
Edward and Albert and an eastern rift which continued into Ethiopia and was filled with lakes
Turkana and the series of Ethiopian lakes. Lake Victoria appeared for the first time in the sag
between the two rifts. A large part of the drainage of the Ethiopian plateau was diverted toward
the Nile Basin.
It took a long time for the water that was directed toward the Nile Basin to find its way to
the Mediterranean Sea. It had first to cut a channel through the Nubian swell, which was
considerably higher than today. The swell presented a formidable barrier for the water
accumulating in the basins further south. A glance at the modern Nubian Nile shows that the river
is still struggling through this stretch; its course runs in great swings and is obstructed by rapids
and cataracts.
The excavation of the channel of the Nile in Egypt was in response to a unique and unusual
event which caused the Mediterranean Sea to become a huge dry desert some six million years
ago. The severing of that sea from the world's oceanic system through the elevation of the
Gibralter Strait converted the Sea into a lake which later dried up as its waters evaporated under
the scorching sun of that episode. The dry Mediterranean was some three to four thousand
meters deep. This caused the few rivers that drained into it to cut down their channels to this new
depth. In the case of the Nile the channel was deepened to as much as four kilometers in its
northern reaches; the early Nile (or Eonile) formed a canyon that was "just as awe-inspiring and
as deep as the modern Grand Canyon of Arizona". This newly formed canyon soon became the
site of sedimentary fill as the rising waters of the regenerated Mediterranean, which obtained
access to the waters of the Atlantic some five and a half million years ago, entered into it
converting it into a gulf. A major river (the Paleonile) pushed its way into the gulf and filled it
with sediments. It is highly probable that the rivers which occupied the early canyon had local
sources; they had not yet developed an African connection. This phase lasted for about four
million years. It is separated from our time by at least two million years.