Ethiopian Rivers & Drainage Systems
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Questions and Answers

What geological features significantly influence the courses of many Ethiopian rivers?

  • Extensive coastal plains and lagoons.
  • Faults and joints. (correct)
  • Volcanic craters and calderas.
  • Glacial valleys and moraines.

Which of the following best describes the geographical distribution of the Western Drainage Systems in Ethiopia?

  • Occupying the central highlands and draining into Lake Tana.
  • Confined to the Rift Valley, with endorheic drainage patterns.
  • Primarily located in the eastern lowlands, draining towards the Indian Ocean.
  • Mainly situated in the westward sloping part of the western highlands and lowlands. (correct)

Which river basin in the Western Drainage Systems flows southward, unlike the others that flow westward?

  • Abay
  • Ghibe (Omo) (correct)
  • Baro-Akobo
  • Tekeze

What percentage of Ethiopia's total area is drained by the Western Drainage Systems, and what percentage of the country's annual water flow do they carry?

<p>40% of the area, carrying 60% of the water flow. (B)</p> Signup and view all the answers

From where does the Abay River originate, according to the provided information?

<p>Lake Tana. (D)</p> Signup and view all the answers

Approximately how long is the course of the Abay River before it joins the White Nile in Khartoum, Sudan?

<p>1,450 kilometers. (B)</p> Signup and view all the answers

Within what elevation range do the streams that drain into the Abay River lie?

<p>500 - 4261 meters above sea level. (D)</p> Signup and view all the answers

What is the name given to the Tekeze River once it crosses into Sudan, where it becomes a tributary of the Nile?

<p>Atbara (B)</p> Signup and view all the answers

Ethiopia is often called the 'water tower' of Eastern Africa because...

<p>The country's estimated surface water potential is 124.4 billion cubic meters. (C)</p> Signup and view all the answers

Which of the following best describes a drainage system?

<p>A principal river and all the rivers that flow into it (tributaries). (D)</p> Signup and view all the answers

A drainage basin is best defined as:

<p>The area from which a river and its tributaries collect surface and subsurface flow, bounded by a water divide. (B)</p> Signup and view all the answers

What factors primarily determine the drainage patterns of major river basins in Ethiopia?

<p>Topographical structures, including the outward sloping plateaus and the inward-sloping Rift Valley. (A)</p> Signup and view all the answers

How does the structural formation of the Rift Valley influence Ethiopia's drainage systems?

<p>It results mainly in an inland drainage system due to its inward-sloping escarpments. (B)</p> Signup and view all the answers

What is the ultimate destination of a river system?

<p>Mouth. (B)</p> Signup and view all the answers

Which of the following constitutes surface water?

<p>Lakes. (B)</p> Signup and view all the answers

What percentage of the earth's fresh water is stored in glaciers?

<p>68.7% (C)</p> Signup and view all the answers

What is the primary characteristic that distinguishes the drainage systems within the Rift Valley from other major river basins in Ethiopia?

<p>Rift Valley streams flow in various directions without a general flow, unlike the more directed flow in major basins. (C)</p> Signup and view all the answers

Which of the following factors primarily contributes to the minimal stream flow observed in the Afar drainage sub-basin?

<p>Low rainfall, very high temperatures, and high evaporation rates. (A)</p> Signup and view all the answers

How do Lakes Afrera and Asale in the Afar region primarily form, considering the region's limited surface water flow?

<p>Their formation is mainly attributed to tectonic activities rather than surface flow. (A)</p> Signup and view all the answers

What is the eventual destination of the Awash River, and how does this contribute to the unique hydrology of the region?

<p>It ends in a series of lakes and marshy areas, with Lake Abe being the largest, creating a closed drainage system. (D)</p> Signup and view all the answers

Considering Ethiopia's water resources in a continental context, how do its rivers generally interact with the surrounding regions?

<p>Ethiopian rivers largely originate from highland areas and cross the Ethiopian boundary, forming major watersheds. (A)</p> Signup and view all the answers

Which of these rivers, originating in Ethiopia, does NOT ultimately flow into the Indian Ocean?

<p>Wabishebelle River (C)</p> Signup and view all the answers

The Baro-Akobo river system eventually contributes to which major river outside of Ethiopia?

<p>The Sobat River (A)</p> Signup and view all the answers

What is a primary characteristic of the Rift Valley drainage system in Ethiopia, influencing its water flow?

<p>Small catchment areas due to outward sloping highlands (B)</p> Signup and view all the answers

Compared to the Wabishebelle River, the Ghenale River is know for what?

<p>Reaching the Indian Ocean. (A)</p> Signup and view all the answers

Which factor most significantly limits the size of the drainage area in Ethiopia's Rift Valley drainage system?

<p>Outward sloping highlands restricting catchment size (A)</p> Signup and view all the answers

The Ghibe/Omo River basin drains into which specific geographical feature, representing an inland drainage system?

<p>Chew-Bahir at the mouth of Lake Turkana (B)</p> Signup and view all the answers

What is notable about the Wabishebelle River despite its large catchment area?

<p>It fails to reach the Indian Ocean. (B)</p> Signup and view all the answers

If a large-scale irrigation project were planned, which river basin, based solely on mean annual flow, could potentially support the largest project?

<p>Baro-Akobo River basin (B)</p> Signup and view all the answers

Which of the following geological processes is primarily responsible for the formation of the lakes around Bishoftu, Wonchi and Hayk?

<p>Volcanic activity leading to crater formation. (C)</p> Signup and view all the answers

What distinguishes Lake Shala from the other lakes in the central Ethiopian Rift Valley?

<p>It is the deepest lake. (B)</p> Signup and view all the answers

How did the arrangement of lakes within the Main Ethiopian Rift most likely occur?

<p>Formation along a linear pattern related to fault systems. (A)</p> Signup and view all the answers

Why is the initial groundwater potential estimate of 2.6 - 6.5 BMC for Ethiopia now considered underestimated?

<p>New studies suggest a higher potential, ranging between 12-30 BMC. (B)</p> Signup and view all the answers

What primary factor hinders the utilization of Ethiopia's abundant water resources?

<p>Underutilization due to various socio-economic factors. (A)</p> Signup and view all the answers

What geological event is believed to have primarily contributed to the formation of the Tana depression?

<p>Slower sinking and reservoir by lava flow. (C)</p> Signup and view all the answers

Based on the provided data, which lake has the smallest surface area?

<p>Lake Hayk (B)</p> Signup and view all the answers

If a research team aims to study the impact of hydroelectric power generation on lake ecosystems, which of the following lakes would be most suitable to visit?

<p>Lake Koka (D)</p> Signup and view all the answers

What is the estimated exploitable hydroelectric power potential of Ethiopian rivers?

<p>45,000 megawatts (A)</p> Signup and view all the answers

Which of the following factors limits the use of Ethiopian rivers for irrigation and transportation, especially in the highlands?

<p>The rugged terrain, including steep slopes and waterfalls (A)</p> Signup and view all the answers

Which river basin systems in Ethiopia are recognized as having a large irrigation potential?

<p>Baro-Akobo and Genale Dawa river systems (D)</p> Signup and view all the answers

What is a major challenge related to utilizing Ethiopian rivers for hydroelectric power generation?

<p>Seasonal flow fluctuations and climate change impacts (C)</p> Signup and view all the answers

Apart from rivers, which of the following water bodies in Ethiopia is most suitable for transportation?

<p>Lake Tana (C)</p> Signup and view all the answers

The Grand Ethiopian Renaissance Dam (GERD) aims to generate how much power upon completion?

<p>6400 megawatts (A)</p> Signup and view all the answers

In which drainage system is the majority of the area under irrigation located in Ethiopia?

<p>Rift Valley Drainage System (D)</p> Signup and view all the answers

What is the estimated annual production of fish from Ethiopian lakes?

<p>31.5 thousand tons (A)</p> Signup and view all the answers

Flashcards

Water Coverage on Earth

About 71% of the Earth's surface is covered by water bodies, mainly seas and oceans.

Freshwater Distribution

Only 2.5% of Earth's water is fresh, with significant portions in glaciers, groundwater, and surface water.

Surface Water Sources

Surface waters include lakes, rivers, atmosphere, soils, and wetlands, representing accessible freshwater.

Ethiopia's Water Bodies

Ethiopia has about 0.7% of its landmass covered by water bodies.

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Drainage System

A drainage system is composed of a main river and its tributaries, where water flows through channels.

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Drainage Basin

A drainage basin is the land area from which a river collects surface and subsurface flow.

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Water Divide

A water divide is a topographic boundary separating different drainage basins.

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Ethiopia's Water Tower

Ethiopia is referred to as the 'water tower of Eastern Africa' due to its significant surface water potential.

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Awash River Basin

The only major river basin in Ethiopia with a catchment of 114,123 km².

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Rift Valley Drainage

A drainage system where streams flow in all directions.

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Lake Abe

The largest end-point lake of the Awash River near the Ethio-Djibouti border.

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Afar Drainage Sub-basin

An area with very little stream flow and high evaporation.

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Ethiopian Watersheds

Twelve major watersheds that separate drainage systems in Ethiopia.

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Baro-Akobo River

A river basin in Ethiopia covering 75,912 km² with a mean annual flow of 23.6 BMC.

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Ghibe/Omo River

Drains an area of 79,000 km² in Ethiopia, with a mean annual flow of 16.6 BMC.

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Southeastern Drainage Systems

Drains the southeastern region of Ethiopia, including Wabishebelle and Ghenale rivers.

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Wabishebelle River

Longest river in Ethiopia with a catchment area of 202,697 km² that fails to reach the Indian Ocean.

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Ghenale River

Carries 25% of Ethiopia's annual water flow, flowing into the Indian Ocean.

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Sobat River

Formed by the confluence of Baro and Akobo rivers in South Sudan.

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Rift Valley

A drainage system with low rainfall, high evaporation, and small catchment areas.

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Juba River

The name of Ghenale River when it crosses into Somalia.

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Ethiopian Drainage Systems

Three major drainage systems: Western, South-eastern, and Rift Valley.

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Lake Tana

The largest lake in Ethiopia, located in a shallow depression.

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Western Drainage System

Largest system, draining 40% of Ethiopia, carrying 60% of water flow.

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Faulted depressions

Areas where lakes are formed due to geological faults creating depressions.

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Crater lakes

Lakes formed in volcanic craters, common in Ethiopia.

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Major Rivers in Western System

Includes Tekeze, Abay, Baro-Akobo, and Ghibe (Omo).

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Man-made lakes

Lakes created by humans, often for hydroelectric projects.

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Abay River

Largest river in volumetric discharge in Western drainage, flowing 1,450 km.

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Lake Abaya

The largest lake in the Ethiopian Rift Valley.

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Ghibe River

Flows southward unlike other rivers in the Western system.

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Tekeze River

Carries 12% of annual flow and drains 82,350 km² in Ethiopia.

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Groundwater potential

The capacity of groundwater resources in a region.

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BMC in water resources

Unit to estimate groundwater potential, ranging from 12-30 BMC in Ethiopia.

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Abay's Tributaries

Mainly left-bank tributaries, draining many streams within varied elevations.

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Underutilized water resources

Ethiopia's significant water resources are not fully exploited for social and economic needs.

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Elevation Range

Abay's streams drain from 500 to 4261 meters above sea level.

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Hydroelectric Potential of Ethiopia

Ethiopia has a hydroelectric potential of about 45000 megawatts from its rivers.

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Grand Ethiopian Renaissance Dam

The GERD is Ethiopia's largest dam, aiming to generate 6400 megawatts of electricity.

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Hydroelectric Power Plants in Ethiopia

Currently, Ethiopia administers 14 hydroelectric power plants generating close to 4000 megawatts.

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Irrigation Potential

Ethiopia's irrigation potential is estimated at 5.3 million hectares, mainly in lowland areas.

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Rugged Terrain Challenges

Ethiopia's rugged terrain limits river usage for irrigation and transportation.

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Navigable Rivers

The Baro River is the only navigable river in Ethiopia.

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Fishing and Recreation

Ethiopian lakes produce an annual fish yield of 31.5 thousand tons, ideal for recreational fishing.

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Seasonal Flow Fluctuations

Seasonal flow fluctuations and climate change affect hydroelectric power generation in Ethiopia.

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Study Notes

Geography of Ethiopia and the Horn (GeES1011)

  • Dire Dawa University, Department of Geography and Environmental Studies
  • Presentation on Chapter Four: Drainage Systems and Water Resources of Ethiopia and the Horn

4.1 Introduction

  • Approximately 71% of Earth's surface is covered by water bodies, primarily seas and oceans.
  • Nearly 97.5% of Earth's water surface is alkaline, concentrated in seas and oceans.
  • The remaining 2.5% is freshwater, distributed as follows: glaciers (68.7%), groundwater (30.1%), permafrost (0.8%), and surface water (0.4%).
  • Surface water includes water in lakes, rivers, the atmosphere, soils, and wetlands

4.2 Major Drainage System of Ethiopia

  • Drainage refers to the flow of water through defined channels.
  • A drainage system consists of a principal river and its tributaries (rivers flowing into it).
  • A river system starts at a source (headwater) and ends at a mouth.
  • A drainage system is a branched network of streams and the adjacent land slopes they drain.
  • Drainage patterns reflect geological processes, rock structure, topography, slope, flow amount, and flow periodicity.
  • A drainage basin is the topographic area where a river and its tributaries collect both surface runoff and subsurface flow.

Major River basins in Ethiopia

  • These patterns are defined by topographic structures, including the outward-sloping Western and Southeastern plateaus, in-ward-sloping escarpments in the Rift Valley creating inland drainage, and fault and joint structures affecting river courses.
  • Western Drainage Systems: The largest system, draining 40% of Ethiopia’s land area and carrying 60% of the annual water flow, includes significant rivers like Tekeze, Abay, Baro-Akobo, and Ghibe (Omo).
  • The Abay river, originating from Lake Tana, is the largest in the western system in both discharge and coverage.
    • It covers 199,812 km2 across Amhara, Oromia, and Benishangul-Gumuz regions.
    • It carries about 65% of the annual water flow in the area.
  • The Ghibe (Omo) River flows in a southward direction and empties into Lake Turkana in the East African Rift Valley, forming an inland drainage pattern.
  • The total mean annual flow from the western basins is estimated to be about 8.2 billion cubic meters (BMC).
  • South-eastern Drainage Systems: Dominated by the Wabishebelle and Ghenale rivers, this system drains the southeast region of Ethiopia, about 25% of the country's annual water flow.
    • The Ghenale River covers approximately 171,042 km2 across Oromia, SNNPR, and Somali regions.
    • Wabishebelle flows to the Indian Ocean; in Somalia, it is called the Juba River.
  • The total mean annual flow from the south-eastern basin is estimated at 23.6 billion cubic meters (BMC).
  • Rift Valley Drainage System: Characterized by limited rainfall, high evaporation, and small catchment areas.
  • The Awash River, originating from the Shewan Plateau, flows about 1250 km and has a catchment area of 114,123 km2, discharging an average of 4.9 billion cubic meters per year, covering Amhara, Oromia, Afar, Somali, Dire Dawa, and Addis Ababa City Administration.
  • In some areas of the Rift Valley, there are no significant streams, especially in the Afar region; the area is characterized by sparse rainfall, very high temperatures, and significant evaporation. This section is characterized by small lakes and marshy areas around it, with Lake Abe being an example on the Ethio-Djibouti border. The area is frequently referred to as the lakes region.

4.3 Ethiopian Lakes

  • Most Ethiopian lakes form in depressions within the Rift Valley.
  • Major lakes include Lake Tana (largest), Lake Abaya, Lake Ziway, Lake Hawassa, Lake Chamo, and others.
  • Lake Tana (3600 km² at 9m deep), Lake Abaya ( 1162km² at 13.1m deep), and Lake Chamo (551km²) are some of the lakes in this region.
  • Lake Shalla (409km²) is reported as the deepest at 266m. Other notable lakes include Lake Ziway and Lake Langano.

4.3 Underground Water and Resources

  • Ethiopia has relatively lower groundwater potential compared to its surface water resources.
  • Currently, groundwater potential is estimated to be 2.6 to 6.5 billion cubic meters (BMC).
  • New research suggests this estimate may underestimate the actual potential, suggesting a more realistic range of 12 to 30 billion cubic meters.

4.4 Water Resources Potentials and Development

  • A) Hydro-electric Potential: Ethiopia has significant potential for hydroelectric power generation (estimated at about 45,000 megawatts), but much of this potential is currently underutilized.
  • The GERD is the biggest dam being currently built in Ethiopia.
  • Projects like the Gilgel Gibe III project (1870 megawatts) are in operation or under construction.
  • B) Irrigation and Transportation: The rugged terrain of the Ethiopian highlands creates challenges for irrigation and transport. The lowlands, though, have a large irrigation potential. The largest irrigation system is from the Baro-Akobo and Genale Dawa systems.
  • C) Fishing and Recreation: Ethiopian lakes are rich in fish. Current fish production is around 31.5 thousand tons, but the potential is higher. Lake Tana is a significant source of fish, estimated at an output of 8,000-10,000 tons annually, while Lake Chamo contributes approximately 4,500 tons annually. Many lakes within Ethiopia offer diverse aquatic life forms, scenic beauty, and important recreational opportunities.

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Geography of Ethiopia and the Horn (GeES1011) PDF

Description

Explore the geographical distribution, key features, and hydrological characteristics of Ethiopia's Western River Drainage Systems. Discover the origin and course of the Abay River and the significance of Ethiopia as the 'water tower' of Eastern Africa. Understand the factors influencing river courses and the unique aspects of each river basin.

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