Nile Hydrology

1
Nile Hydrology

• 1.096 Preliminary Research
• Anthony Makana Paris
• 2.19.04

2
General Facts

• Length 6700 km
• Total Catchment Area 3 million km2
• Average Runoff 30 mm
• Major contributors of total flow East African
  lake region, Ethiopian Highlands
• Main Tributaries White Nile, Blue Nile and Main
  Nile
• Wide band of Latitude 4oS to 32oN

3
Flow Patterns

• White Nile Atbara Seasonal
• July Oct. peak
• White Nile fairly constant

4
Flow Patterns

• Seasonal Contributions

5
Sectional View
6
Elevations
7
The Lake Victoria Basin

• Inflows
• Rainfall 1151 mm, 122 km3/yr
• Tributary 276 mm, 22.4 km3/yr
• Evaporation 1116 mm, 107 km3/yr
• Outflow 311 mm, 39.8 km3/yr
• Characteristics
• Provides a relatively steady baseflow.

8
The East African Lakes below Lake Victoria

• Lakes -- Albert, Kyoga, Edward
• Inflows
• Rainfall 10.3 km3/yr
• Tributary 10.6 km3/yr
• Evaporation 16.3 km3/yr
• Outflow 45 km3/yr
• Characteristics
• Outflow contribution to Nile dominated by lake
  Victoria.
• Dramatic variation in flow level historically

9
The Bahr el Jebel the Sudd

• Rainfall 871 mm
• Evaporation 2150 mm
• Characteristics
• Most complex of the Nile reaches due to having
  many seasonal inflows.
• Permanent swamp land, seasonal flood plains that
  are inundated
• High levels of evaporation and transpiration
  from vegetation (ex papyrus).
• Little seasonal variation with annual outflow
  about half the inflow.
• Jonglei Canal
• Reduce evaporation losses in Sudd

10
The Bahr el Ghaal Basin

• Characteristics
• Ouflow to the White Nile is almost negligible
  (3)
• Upper basins have relatively high rainfall, but
  the river flows spills over into flood plains
  resulting in almost total lost to evaporation.
• Sediment loads of these rivers if greater than
  lake-fed Bahr el Jebel
• Higher potential for alluvial channels.

11
The Sobat Basin Machar Marshes

• Characteristics
• The regime of Sobat and its tributaries is
  complex.
• Most of the runoff develops in the mountains and
  foothills of Ethiopia.
• Pibor drains a wide area of plains, but only
  contributes significantly in times of high
  rainfall.
• Provides about half of the flow for the White
  Nile.
• Relatively same outflow as the Sudd.
• Relatively little is known about he hydrology of
  the basin area, due to the river straddling the
  border of Sudan and Ethiopia.
• The system is reasonably self-contained with
  water stored in the channel and flood plain
  during high flow periods, returning to the
  channel when the flow recedes, losses to
  evaporation and soil moisture recharge.

12
The White Nile below Malakal

• Characteristics
• Drops 13 m over 840 km
• Tributary inflows are sporadic and small
• Flood plain storage results in delay of outflow
  and increased loss to evaporation.
• The Jebel Aulia dam further raised upstream river
  levels after June 1937
• Irrigation and evaporation have led to increased
  losses.
• Outflow is delayed to supplement the Blue Nile in
  low flow season due to the dam
• Sudd provides the baseflow component
• Sobat basin contributes the seasonal component

13
The Blue Nile and its Tributaries

• Characteristics
• Provides the greater part of flow of the Main
  Nile (60)
• Limited information is known about its hydrology,
  especially in its upper basin within Ethiopia
• Geography
• Begins in Ethiopian Plateau
• Elevations of 2000-3000 m, peaks of 4000m
• Very broken and hilly, grassy uplands, swamp
  valleys, and scattered trees.
• Deep ravines and canyons (1300m at places)
• Lake Tana
• 1800m
• Surface Area 3000 km2
• Blue Nile leaves and travels through series of
  cataracts.
• Travels through the Sudan Plains
• Slopes westwardly from about 700 m
• Covered with Savannah or thorn scrub

14
The Blue Nile and its Tributaries

• Major Tributaries
• Below reservoir
• Rahad
• Dinder
• Similar basins to lower Blue Nile, highly
  seasonal
• Above reservoir
• Dabus wetland area of 900 km2
• Didessa smaller swamps
• Drains southwestern humid portion of the
  Ethiopian basin, contributes significantly to
  total flow
• Reservoir Storing
• Roseires Dam (2.4 km2)
• Sennar Dam (0.5 km2)
• Largest Sediment load (especially during the
  flood season)
• 140- million tonnes per year

15
The Atbara Main Nile to Wadi Halfa

• Convergence of White Nile and Blue _at_ Khartoum
• Atbara
• Only major tributary after Khartoum
• Most seasonal of all tributaries
• Drains northern Ethiopia (68,800 km2) and
  mountains north of Lake Tana (31,400 km2)
• Topography
• Sabaloka gorge 80 m north of Kartoum
• Arid plain dotted with low hills and rock outcrops

16
The Main Nile in Egypt

• Characteristics
• Major issues are storage and water use
• No flows are generated below the Atbara
  confluence
• Aswan High Dam
• Storage of flood water
• 1/3 lost to reservoir evaporation
• Allows increased water availability for
  irrigation hydroelectric
• Annual release decreased, but provides a steady
  yield downstream.