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Rivers and Fluvial Systems in
Egypt
Which of the following is the
longest river?
A) Mississippi
B) Nile
C) Amazon
D) Congo
COMPARISON OF NILE TO
OTHER RIVERS
River
Length
Drainage area
Annual Discharge
(km)
(103 km2)
(109 m3)
Nile
6825
2960
84
Amazon
6700
7050
5518
Congo
4700
3820
1248
Huang Ho
4630
673
123
3270
562
(Yellow)
.
.
Mississippi 970
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The drainage basin
A network of
streams that
carries all the
surface water
within its area.
Boundaries are
drainage
divides.
Drainage basin of the Nile
True or False
The drainage basin area and discharge of
the Mississippi are greater than those of
the Nile.
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How do drainage networks
develop?
All streams tend to extend their channels in the
upstream, or headward, direction.
Waterfalls
Waterfalls and rapids form when the stream encounters
a contact between rocks that differ in their erosional
resistance.
Usually, a less resistant rock is overlain by a more
resistant rock.
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The Nile cuts through which
resistant formation to form the
first cataract?
A) Eocene limestone
B) Aswan granite
C) Nubian sandstone
Flow of water in a stream
Flow types

Laminar vs. turbulent
Discharge and velocity
Units: m3/s
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Stream hydrographs
The record of discharge vs. time during a
flood, a year, or any time period.
Stream sediment
Streams move larger and larger clasts on their
beds as the velocity increases—the initiation of
movement is called entrainment.
Hjulstrom diagram
Transportation
Dissolved load

Carried in solution by the stream
Suspended load

Finer particles that stay in suspension. The upward
components of velocity in turbulent flow are greater
than the fall velocity of the particle (Stoke’s Law)
Bed load

Move in contact with bed by rolling, sliding or
saltation.
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Two important concepts
involving stream sediment
Capacity: the total amount of sediment a
stream can carry. (Sum of suspended load
and bed load)
Competence: the largest clast a stream is
capable of carrying
The yearly Nile floods (before the
construction of the high dam) are
the result of discharge from the:
A) Atbara
B) Blue Nile
C) White Nile
D) Both A and B
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Depositional processes
Channel patterns



Straight
Meandering
Braided.
Meandering streams
Flow in a meandering channel
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Natural levees
Which of the following rivers has
the highest competence
A) The Mississippi River at New Orleans
B) The Madison River in Montana (a
tributary of the Mississippi in the Rocky
Mountains)
C) A wadi in the south Sinai.
Migration of meanders
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Meander Abandonment (Cut off)
Braided streams
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Braided Streams
Braided channels, Wadi Qena
Alluvial fans
Decrease in competence due to increase in width and/or
decrease in slope.
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Alluvial fans
Death Valley
Alluvial fans in the South Sinai
Deltas
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Deltas
Deposit formed when a river enters a
standing body of water (lake or ocean)
As sediment is deposited, the delta
progrades.
Three types of sediment: topset, foreset,
bottomset
Topset and foreset beds in a glaciomarine
delta
Growth of a delta
Distributaries, crevasse splay deposits
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Delta growth and progradation
Hebgen Lake
Types of deltas
River dominated

Distributaries dominate
Tide dominated

Shallow, tidal channels and low islands
parallel to tidal channels
Wave dominated

Beach ridges, cuspate appearance
River dominated deltas
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River dominated deltas
Mississippi delta
Shift in delta lobes
Tide dominated deltas
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Ganges-Brahmaputra: Bangladesh
Wave dominated deltas
San Francisco-Brazil
The Nile Delta is:
A) Wave dominated
B) Tide dominated
C) River dominated
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Equilibrium in stream systems
Graded stream—a stream in equilibrium;
the channel neither aggrades or degrades
Base level—the elevation to which the
stream becomes graded.
Longitudinal Profile of the Nile
Disequilibrium
Climate change
Tectonics
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Human impacts on equilibrium
True or False
The steepest part of the longitudinal profile
of the Nile extends from Aswan to the
Mediterranean.
Stream terraces
Stream terraces; remnants of former floodplains
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Madison River, SW Montana
2 types of terraces
Floods (Flows greater than bankfull capacity)
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Characterization of floods
Magnitude (peak discharge)
Frequency (recurrence interval or return
period)


R.I. = n + 1 / i , where n = number of years of
record and i is the magnitude order rank. i is
based on the annual flood series (maximum
discharge in each year) ranked from highest (i
= 1 to lowest)
The R.I. of bankfull flow is about 1.5 years for
most streams.
Gauging station
Measures river stage (elevation): this
value can be converted to discharge
Egytpian gauging stations: the
Nilometer
Aswan
Cairo
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True or False
If the base level of a stream drops, it will
erode and deepen its channel in order to
merge smoothly with the new base level
elevation.
Evolution of the Nile
The Messinian Salinity
Crisis
At the end of the Miocene, the
Mediterranean Sea (the remnant of
the Tethys Sea) became separated
from the Atlantic. Evaporation
caused the Med. to nearly dry up
and the deposition of evaporite
deposits. The floor of the dried up
sea was as much as 2-3 miles
below sea level.
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Distribution of evaporite deposits
Early models called for
catastrophic drying (~1000
yr?) and filling of the
Mediterranean.
Exposure of gypsum on Sicily
due to uplift.
http://www.see.leeds.ac.uk/structure/tecto
nics/messinian/
Effects on the Nile
Rivers around the Mediterranean cut huge
canyons because of the lowering of base level
during the Salinity Crisis
The Nile canyon was deeper than the Grand
Canyon
This stage of the Nile is called the Eonile
The existence of this canyon (now filled with
sediment) as far south as Aswan was confirmed
during borings for the Aswan Dam
Limestone cliffs along the Nile are remnants of
this canyon
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Comparison of the Eonile and
Grand Canyons
•Canyon was 570m below sea
level at Cairo and 170m at
Aswan
As it formed, the Eonile eroded its
channel headward and captured
the drainage of the “Qena River”
Refilling of the Mediterranean
Occurred about 5.3
MY BP



May or may not have
been catastrophic
Some accounts
suggest a waterfall
3000 ft high
Much more discharge
than Niagara
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Formation of the
Paleonile
During the early Pliocene,
the canyon was filled by a
long shallow arm of the
Mediterranean. Gradually,
the canyon filled with
sediment (several hundred
meters higher than the
present valley) and an a
north-flowing river was
established.
The Prenile
During the early to mid-Pleistocene (the
ice ages), flow in the Nile was intermittent
and had very low discharge at times.
During the middle Pleistocene (~800,000
yr BP), the Nile began to receive runoff
from Ethiopian sources. This large, high
discharge river, the Prenile deposited
coarse sands and gravels in the valley that
make good aquifers today.
The Neonile
From about 400,000 yr BP to 12,500 yr B.P., the
Nile was separated from its southern
headwaters by a huge lake or savanna in
Sudan. The Neonile was a small river with low,
intermittent discharge. The tropical headwaters
were dryer at times during the ice ages; Lake
Victoria completely dried up around 15 kyr BP.
At ~12,500 yr BP, the Nile became re-integrated
with its southern headwaters because of higher
rainfall in the White Nile basin and overflow of
Lake Victoria and established its present pattern
of yearly summer floods. (The Modern Nile)
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Modern Nile
The early Holocene was a period of high
flows and regular floods. However, flows
gradually decreased to a minimum about
4200 yr B P, which corresponds to the end
of the Old Kingdom and the beginning of
the first intermediate period.
Nile floods during the Holocene
The lower Nile has been
integrated with its headwaters in
Ethiopia and Lake Victoria:
A) Since Miocene time
B) Since the beginning of the ice ages
C) For approximately the last 12,500 yr.
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The Nile and Irrigation
True or False
The Nile has had regular stable flows in
Egypt since before the ice ages.
Integration of the Nile tributaries into
the modern river was accomplished:
A) In the Miocene about 6 my before present
B) In the Pliocene about 5 my before present
C) In the Pleistocene about 800,000 yr
before present
D) In the late Pleistocene about 12,500 yr
before present.
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The delta: most intensely irrigated part
of the drainage basin
Major channels, canals and drains
Detailed map of canals and drains: 10,000 km total
HISTORY OF IRRIGATION IN
EGYPT
PRE-DYNASTIC TO 19TH CENTURY
BASIN IRRIGATION—FEEDER CANALS TO DIKED
BASINS DURING FLOOD
ONLY LOW AREAS
WINTER CROP ONLY
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IRRIGATION, CON’T
NEW KINGDOM ONWARD
HIGH AREAS (NATURAL LEVEES OF RIVER)
WATER LIFT—SHADEUF
ADD SUMMER CROP
The Shadeuf
IRRIGATION, CON’T
19TH CENTURY –PERENNIAL IRRIGATION
WATER WHEEL
LOW DAMS TO RAISE WATER LEVEL TO HEAD OF CANALS
SUMMER CROP---COTTON
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IRRIGATION, CON’T
20TH CENTURY
ASWAN DAM—1902
DRAINAGE BASIN PLANS
Dams in headwaters
Abandoned—political unrest & instability
EGYPTIAN REVOLUTION-1952- NASSER BECOMES
PRESIDENT
ASWAN HIGH DAM
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Aswan High Dam Timeline
1952-Egyptian revolution; Nasser becomes president
Early-mid 1950s-Aswan dam planning and design. Western powers
plan to finance construction
1956: Nasser nationalizes Suez Canal
1956: Israel invades and captures Sinai
1956: England and France send expeditionary force to secure canal
zone
1956: US forces cease fire on Israel, Britain, and France
1957: Israel withdraws from Sinai; Canal left in Egyptian hands
Late 1950s: US withdraws offer to pay for High Dam: USSR steps in
and jointly builds dam with Egyptians.
1964: Dam closed and reservoir starts to fill
1970: construction complete
1976: Reservoir reaches capacity
Dimensions of the Aswan
High Dam





Size: 2nd largest in world
Height: 111 m
Length at crest: 3600 m
Width: 980 m at base
200 m grout curtain to granite
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Cross section of Aswan High Dam
Teton Dam: Failure of an earth dam by piping
Observation tower and
monument
Lake Nasser
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PURPOSE AND STORAGE
PURPOSE OF DAM
 Flood Control
 Water Conservation
 Hydropower
AMOUNT OF WATER
STORED
 Total: 32 billion m3
 Available for use: 22
billion m3
 Evaporation and
seepage: 10 billion m3
True or False
The core of the Aswan high dam is
composed of low permeability clay.
Pre vs. post dam hydrology
Aswan
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Breakdown of water discharge
and sediment load
Sediment storage in reservoirs
Roseires reservoir (Blue Nile, downstream
from Ethiopian highlands; 1966). Storage
capacity reduced by 60% in 1996;
deforestation and expansion of agriculture
Khashm el Girba (Atbara River, 1964; site
of relocation of Nubians from Lake
Nasser); 40% reduction in storage by 1996
Lake Nasser/Nubia
Sediment deposition has formed the “New Nile
Delta”; by the mid 1990s was 200 km long, 12
km wide and 40 m thick. Located mostly in
Sudan. Velocity at the time of arrival of the
annual flood decreases from 1 m/s to ~0.02 m/s:
almost 100% trap efficiency.
However: Because of the size of the lake, the
reservoir storage allocated to sediment is
estimated to be 300 yr. Existing and new dams
upstream trap sediment that would be deposited
in Lake Nasser.
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ADVERSE EFFECTS OF LAKE NASSER
RELOCATION OF 400,000 NUBIANS FROM AREA OF
LAKE (This number varies widely with reference)
FLOODING OF TOMBS, TEMPLES, MONUMENTS
Four colossal statues of Ramses II disassembled and relocated;
funded partially by revenues from King Tut tour of 1970s.
DOWNSTREAM ADVERSE EFFECTS
OF DAM
SEDIMENT TRAPPING UPSTREAM AND DOWNSTREAM
EROSION
LOSS OF SILT-BRICK MAKING
SAND DUNE MIGRATION
COASTAL EROSION AT DELTA
INCREASED USE OF PESTICIDES AND HERBICIDES
INCREASED USE OF CHEMICAL FERTILIZERS
RISE IN WATER TABLE AND SOIL SALINIZATION
CHANGE IN WATER QUALITY
Decr. Turbiity; Incr. Dissolved Solids; Incr. Phtoplanton & Algae
True or False
Lake Nasser is likely to have serious
problems with sediment deposition within
the next few decades.
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Irrigation using groundwater
Aquifer Map of Egypt
The age of the Nubian
sandstone is:
A) Cretaceous (late Mesozoic)
B) Eocene
C) Precambrian (age of the basement
complex)
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The water table
Point below which the
pores are totally filled with
water.
Conditions above and below the water table
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Recharge and discharge
Recharge areas: high points on water
table. Discharge areas: low points
Water table
The water table usually mimics the land
surface: higher under uplands and lower
under valleys, lakes, streams, etc.
Unconfined aquifers
Upper boundary is water table; GW flows in
direction of slope of WT: hydraulic gradient;
water will rise in a well to the level of the WT
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Confined aquifers
Confined above and below by low K units. Water in a well
rises above the top of the aquifer to the
POTENTTIOMETRIC SURFACE. The slope of the PS
controls the direction of flow.
Artesian aquifers
Another name for confined aquifer.
Flowing artesian well; the water rise above
land surface under its own pressure; the
potentiometric surface is above the land
surface. Nubian aquifer is this type.
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Flowing artesian well in Nubian
aquifer
Nubian aquifer system
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