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Nile River Basin- GGY 480 Final Project
Transcript of Nile River Basin- GGY 480 Final Project
The basin spans 11 countries and has a catchment area of almost 3 million sq. km.
It also encompasses part of the world's hottest desert, the Sahara.
The Nile Basin Conflict
Due to the basin's large size, there are very strong differences in regional climate.
The riparian countries are located near the low pressure zone created by the ascending air of the Hadley cells.
This creates plenty of precipitation.
Downstream countries are located near the subtropical high pressure zone that occurs around 30 degrees North due to the descending air of the Hadley and mid-latitude cells.
This zone results in dry conditions for much of the year.
Note the areas of high precipitation.
Now note the arid area of
Egypt and Sudan.
The water of the Nile is derived mostly from the rainfall in these areas.
Egyptians used the seasonal flooding of the Nile to develop some of the world's first irrigation practices around 6000 BC.
More recently, colonial interests in the area maintained Egypt's right to the majority of the Nile waters through (often disputed) treaties.
Egypt is heavily dependent upon these waters, especially for agriculture.
Therefore, conflict exists between the riparian nations, especially Ethiopia, which feel that they deserve rights to the water that originates within their borders, and Egypt, which built an economy dependent upon the flow of the Nile.
To gain a better understanding of the processes that influence this conflict, let's follow
the Nile's water.
The Basin Basics
This is Lake Victoria.
Lake Victoria is situated between the two branches of the East African Rift. Tributaries drain these regions of high elevation to the lake, the second largest in the world.
The Kagera River is of particular importance, as it is the principle river that drains the mountains of Burundi and Rwanda.
However, the majority of the water in the lake is not explicitly delivered by these small rivers. The lake is so large that it maintains its own micro-weather system, called a "nocturnal cloud," that causes precipitation, that contributes around 82% of the lake inflow.
The system experiences a
distribution of rainfall, with one peak from
and the other between
Notice that the evaporation from the lake is about equal to the rain over the lake.
The lake has such a large storage area (2,760 cubic km) and only one outflow location, so the water is retained for a while (23 years), and there are not seasonal differences in outflow like the ones seen in the inflow.
These waters are necessary for:
Hydropower in numerous countries
Agriculture, especially in Egypt
Ecological uses in the wetlands of Sudan
Tourism industry (of the entire Nile)
Navigation and transport
Location of outflow:
Owen Falls Dam (Nalubaale Power Station)
Recently, hydroelectric generation has been curtailed here due to low water levels in Lake Victoria and possible water mismanagement by the power company.
, especially near the shore of the lake as people look for a source of income, increase demand for the resources as well as increasing pressures on the system.
Lake Victoria serves as the source of the White Nile River. Due to its large storage capacity, the lake is relatively steady source of water for the entire Nile itself, as the Blue Nile flow is seasonal.
Evaporation and average rainfall over the lake are about equal. Therefore, periods of high rainfall over the lake or high tributary inflow can have relatively large, disproportionate effects on the lake balance and outflow, leading to changes in the flow of the White Nile.
Note the recent decrease in lake levels.
Other than low water levels, what are the issues facing the Lake Victoria Basin?
Increased livestock presence
Loss of wetlands (buffers) as they are converted for grazing
(Human and animal)
Increased land use and conversion
Erosion of sediment
Declining water quality (and increased nutrients)
Loss of Biodiversity, Negative impacts on local fisheries
In Uganda, the outflow of the Victoria Nile is modified slightly by Lake Albert on the border between the Democratic Republic of the Congo and Uganda and Lake Kyoga.
Water leaves Lake Victoria here and flows north in the form of the Victoria Nile.
However, the land is pretty flat here, and the trip is relatively uneventful.
Murchison Falls, where the Victoria Nile meets the western branch of the African Rift
Again, this area is pretty flat.
However, there are many smaller streams along this route, called torrents, that drain portions of the basin. These are highly seasonal, and add to the stable flow of the White Nile that originates from Lake Victoria.
The high seasonality means that flooding is extensive during the rainy season.
The Sudd, or the Bahr al Jabal in South Sudan
"Sudd" aptly means "barrier"
This area is the largest freshwater wetlands in the world when flooded. Its size averages 30,000 sq. km. but can be over four times that size dependent on inflow.
The area is impassible by foot or boat, and is home to villages of nomadic people.
The Sudd stores floodwaters from the torrents and the inflow sediments carried over the land by the Bahr al Jabal.
Waters are stored in a "channel and lagoon" system. Due to the low banks on many of the channels, floodwaters overflow and are either stored within the heavy clay soils or flow parallel to the main channel, eventually rejoining it.
Half of the inflow of the Sudd is lost to evapotranspiration.
Both evaporation and uptake by the thick vegetation are responsible for large decreases in the outflow. In addition, pastoralism is key in this area, so livestock are responsible for a noticeable amount.
Interaction between hydrosphere, atmosphere, and biosphere due to the geomorphology.
An engineering project, the Jonglei canal, was proposed in the mid-1900's in order to force more of the water to the White Nile for later use. However, political instability forced Sudan to stop work on the project until 2008, when Egypt and Sudan agreed to finish the project.
Egypt and Sudan will gain the water, while South Sudan (and possibly other riparian nations) will face the consequences. Vegetation that relies on the flooding regime may die, and in conjunction with an alerted flow (or complete loss), there may be severe ecological ramifications. Draining the region altogether could have environmental effects similar to the loss of the Aral Sea, according to some researchers.
After leaving Lake Albert, the river is first called the Albert Nile and then transitions into the Bahr el Jebel.
Waters leave the Sudd and enter Lake No.
Here, they are joined by the output of the Bahr el Ghazal, which drains the eastern Central African Republic.
The outflow of this lake forms the base flow of the White Nile,
which is then joined by the Sobat River, which is reliant on seasonal input from the Ethiopian highlands.
Egypt's Historic Water Rights
An opinion piece in the Egyptian newspaper, Al-Ahram, titled "The water situation for Nile Basin countries"
1 May 2014
States world's water "unfairly distributed"
But there is enough freshwater in the world that there should be plenty for current use
During periods of Blue Nile flooding, the White Nile flow is restricted, backs up, and these areas experience mild flooding.
Jabal al Awliya Dam, Sudan
Now that we've seen where the Blue and White Nile meet, why don't we examine the origins of the Blue Nile, the source of the majority of the Nile Basin's water?
Origins of the Blue Nile
In the summer, southeasterly winds blow from the Indian Ocean and are forced to rise over the Ethiopian highlands, causing a great deal of precipitation.
Steep drop from plateau to Sudan plains
Lake Tana-site of some storage, but actually less than expected
Roseires Dam: Main reservoir for storing Blue Nile waters (built in 1966)
Blue Nile first of the tributaries where sediment load is critically important
significant sediment load
during flood period because basin has
(due to flooding),
rates due to steep changes in topography
capacity of Roseires reservoir reduced by about a third
in thirty years, had to be raised
-strategy is to delay filling of reservoirs until the peak of flood has passed through the reservoir "as sediment load is greatest on the rising limb of the hydrograph"
Blue and White Niles meet in Khartoum
Can see differences in sediment load carried by each
Natural vegetation along this section is sparse due to
Salinization of the Nile
Historically, salinization was not a problem for the Nile because flooding traditionally transported the salts out of the main channel and deposited them as a new layer of fertile soil. This is what led to the agricultural prosperity of the region.
Construction of the Aswan Dam and a more modern canal system, however, changed this regime, and now salinization is becoming a problem.
Water irrigated for agriculture leaches through the soil, accumulating salts and nutrients (including those from fertilizer), and is then returned downstream (especially in the Delta) to the river. Lands irrigated with this downstream water are affected by this increase in salinity, which causes a shift in which crops will grow in those regions.
Nile River Delta at night
Clearly, development is reliant upon the water of the river
Pumped irrigation along this stretch has allowed development in these Nile regions
Dinder and Rahad Rivers actually contribute more to main flow than Lake Tana, by some studies
Elevations of 2000-3000 m, but some up to 4000 m or more
Unexpected course of rivers may follow original drainage pattern due to the volcanic centers of some of the highland peaks
Blue Nile contributes 60-85% of the Nile flow, but experiences high seasonal and annual changes
Many perennial streams with highly seasonal flow
Recent decrease in flows
Not well studied
Blue Nile Falls
-sediment load estimated in 1997 at 140 million tons during flood season
-sediment concentration 6000 ppm in August, before peak discharge, and decreases to end of flood
Completion ceremony of dam heightening project on 1 January 2013
Egypt's water rights can never be revoked
Gives water statistics for each country in the Nile River basin, and concludes for most riparian countries that they "logically cannot make demands on Nile water"
"Any talk of Ethiopia's need for Nile water that goes to Egypt, where humans, crops, and stock entirely rely on this water, ignores reality and is manipulated by some-especially in some intelligence think tanks in the West"
"Nile Basin countries have much more than their needs and thus can increase consumption without encroaching on the shares of Egypt and Sudan, unless the aim is to ignite a water feud caused by foreign incitement or domestic animosity"
"Any drop in water revenues flowing to Egypt from the River Nile is a direct threat to life"
Due to the construction of the dam, the groundwater level is perpetually high (as compared to the levels during drought, which used to be a natural, annual occurrence) at 1 to 2 meters. The water can then be pulled from the ground by capillary action and subsequently evaporated, leaving small amounts of salts every time this happens. Because there isn't enough subsurface drainage, the salts have accumulated and now salinization negatively impacts crop yields.
Built in 1964, after the Egyptian Revolution of 1952 resulted in surges of industrialization, in order to control floods and droughts that negatively impacted agriculture.
The dam resulted in an overall increase in agricultural production, employment, electricity production, and improved navigation, which positively impacted tourism.
Sediment deposition in reservoir has lowered the water storage capacity at Lake Nasser even though dead storage should have allowed 200-500 years to pass before this occurred. (Due to uneven sediment deposition.) There have also been reports of erosion along the Egyptian coast.
Before the dam was built, 50% of the Nile flow drained into the nutrient-poor Mediterranean Sea, carrying with it phosphate and silicate that resulted in seasonal phytoplankton blooms. These blooms served as the bottom of the food chain for marine fisheries, which saw a decrease in catch after the dam became operational in 1965.
The fisheries seem to have rebounded now, and there are now smaller year-round blooms that could be the cause of this.
Aswan High Dam
In the Lake Victoria Basin
In the Ethiopian Highlands
The removal of vegetation in these regions can have detrimental effects on water quantity, water quality, soil and erosion, and biodiversity and at a local scale.
At a global scale, deforestation increases greenhouse gas emissions (especially carbon dioxide).
(Forest extent is shown in green, with red showing forest lost, and blue showing forest gained.)
Climate Change Impacts and Future Management Strategies
Current temperature and precipitation amounts
Projected Changes in Temperature
Projected Changes in Precipitation
Montane Grasslands and Shrublands
(surrounded by moist broadleaf forests
at the base of mountains)
Moist broadleaf forests
Flooded grasslands and shrublands
Affected by high amount of precipitation,
Affected by dry conditions, low precipitation
The NBI is a regional intergovernmental partnership between the ten riparian nations (but not Egypt) that allows for multinational dialogue between stakeholders regarding management decisions and joint planning.
Political instability and poverty in many of the riparian nations has not allowed them to move forward on water development plans before now. However, the creation of the Nile Basin Initiative is initiating those conversations and connections.
Currently, Ethiopia is in the process of building the Grand Renaissance Dam, which could impact the amount of water that reaches Egypt. Egypt sees this as a danger to the country's livelihood and to the lives of its people, and has threatened war.