Video Lesson

Lesson Objective

At the end of this section, you will be able to:

• Recognize the concept natural resources;
• Describe the classification of natural resources
• Elaborate major drainage systems of Ethiopia.
• Explain the distribution of the major water resources in Ethiopia.

Brainstorming Question

What is natural resource?

Key terms and concepts

Ethiopia, a nation abundantly blessed with diverse natural endowments, plays a pivotal role in sustaining both its economic productivity and societal consumption. These natural resources are broadly categorized into two main groups: renewable and non-renewable. Renewable resources, such as water, wind, solar energy, and biomass, possess the inherent ability to regenerate naturally over time. Conversely, non-renewable resources—encompassing minerals, coal, oil, and natural gas—are finite and cannot be restored once exhausted.

Despite its wealth in natural resources, Ethiopia faces mounting challenges that threaten their sustainability. Rapid population growth, agricultural expansion, urbanization, internal migration, climate change, and environmental pollution exert immense pressure on the country’s land, water, forests, and wildlife. This strain has catalyzed a cycle of environmental degradation, jeopardizing the long-term viability of these resources and undermining the ecological stability of the nation.

DRAINAGE SYSTEMS OF ETHIOPIA

What is a drainage basin system?

Drainage systems describe the flow patterns and directional discharge of rivers and streams, primarily influenced by geological formations and structural events from the Cenozoic era. Ethiopia’s drainage systems can be classified into three primary categories:

1. Western (Mediterranean Sea) Drainage System
2. Southeastern (Indian Ocean) Drainage System
3. Inland (Rift Valley) Drainage System

Fig 3.1. The Drainage Systems of Ethiopia

The Western (Mediterranean Sea) Drainage System

1. The Western (Mediterranean Sea) Drainage System

The Western drainage system is the largest of the three in terms of both catchment area and water volume, contributing approximately 60% of Ethiopia’s total annual water discharge. It comprises significant rivers and their tributaries, including:

• River Tekezze: Drains the western Lasta Massif, northern Gondar/Semein, and central Tigray.
• River Abbay: Originating from the Gojjam plateau, it meanders in a semi-circular course around Lake Tana, delineating the boundaries between southeastern Gondar, Gojjam, and Shewa.
• River Baro-Akobo: Collects waters from the wettest southwestern highlands before crossing into Sudan to join the Nile.

These rivers converge within Sudan, eventually discharging into the Mediterranean Sea.

The Southeastern (Indian Ocean) Drainage System

This system, the second largest in Ethiopia, comprises the Genale and Wabe Shebelle rivers, which originate from the highlands of Hararghe, Sidamo, Bale, and Arsi. Together, they contribute roughly 32% of the country’s annual water flow.

• Wabe Shebelle: The longest river in Ethiopia, it terminates at the Benadir coast of Somalia without reaching the Indian Ocean.
• Genale: Joins the Dawa River at the Ethiopia-Somalia border, where it is renamed the Juba River, continuing to the Indian Ocean.

The Inland (Rift Valley) Drainage System

The Rift Valley drainage system is the smallest in terms of catchment area, water discharge, and volume. It comprises numerous smaller streams such as the Bilate, Gedabo, Segan, Meki, and Katar, which feed into lakes such as Abbaya, Chew Bahir, and Ziway. The main rivers, Awash and Omo-Gibe, are crucial for the region:

The Awash River: Originates in the Shewan plateau and traverses the Rift Valley, terminating in Lake Abbe along the Djibouti border. The river’s lower basin forms expansive alluvial plains ideal for agriculture.

WATER RESOURCES OF ETHIOPIA

Ethiopia, often referred to as the “Water Tower of Northeastern Africa,” ranks second only to the Democratic Republic of Congo in terms of water resources on the continent. Its wealth in water is attributed to substantial average annual rainfall, which supports numerous rivers, lakes, and significant groundwater reserves.

Major Rivers of Ethiopia and Their Characteristics

Ethiopia’s rivers, originating from its highlands, are characterized by:

• Seasonal fluctuations in water volume, heavily influenced by precipitation patterns.
• Steep profiles, with rivers flowing from elevated terrains to low-lying regions.
• Rapids and waterfalls, especially along steep gradients.
• Deep gorges and valleys, often serving as natural boundaries.
• Renaming across borders, as some rivers acquire new identities once they exit Ethiopia (e.g., River Abbay becomes the Blue Nile in Sudan).

Lakes of Ethiopia

Ethiopia’s lakes are predominantly located on plateaus or within the Rift Valley. They are classified into highland and Rift Valley lakes, with their formation largely driven by tectonic activity during the Quaternary Period.

• Highland Lakes: Include crater lakes (e.g., Haik and Hashenge) formed by volcanic explosions and watershed lakes (e.g., Lake Tana) created by lava flows.
• Rift Valley Lakes: Clustered along linear depressions and basins within the Rift Valley, showcasing unique ecological characteristics.

Figure 3.2: Major Rift Valley Lakes of Ethiopia

Table 3.2: Depth, Area and Location of Ethiopian Lakes

Significance of Ethiopian Lakes and Rivers

Ethiopian rivers and lakes are indispensable for the nation’s socio-economic growth. They facilitate hydroelectric power generation (e.g., Gibe and Awash projects), support the fishing industry, and serve as key irrigation sources. Furthermore, their scenic beauty and biodiversity offer untapped tourism and recreational potential.