Freshman Geography Lecture 3

Course Overview

• Course Title: Geography of Ethiopia and the Horn

• Instructor: Belete Ejigu (PhD), Assistant Professor of Urban Planning and Development, Addis Ababa University

• Level: Freshman Course

• Date: January 2021

Chapter Three: The Topography of Ethiopia and the Horn

Content Breakdown

• Introduction

• General Characteristics of Ethiopian Physiography

• Physiographic Divisions of Ethiopia

• Impacts of Relief on Biophysical and Socioeconomic Conditions

Objectives of Chapter

• Describe the topography of Ethiopia and the Horn

• Identify the physiographic divisions of Ethiopia

• Explain physiographic characteristics of the Rift Valley

• Discuss the impacts of relief on biophysical and socioeconomic conditions

Introduction to Topography

• Determined by Cenozoic Era geologic activities

• Uplifting of the Arabo-Ethiopian swell leading to a highland plateau and mountains

• Major faulting divides plateaus into units and forms valleys; leads to lake depressions

General Characteristics of Ethiopian Physiography

• Diversity in landforms:

  • Flat-topped plateaus

  • Rugged mountains

  • Deep river gorges

  • Vast plains

• Altitude Variation:

  • Ranges from 125 m below sea level (Kobar Sink) to Mount Ras Dashen at 4,620 m a.s.l (4th highest mountain in Africa)

• Known as the Roof of East Africa due to its significant elevation

• Highland Characteristics:

  • Over 50% of land above 1,000 meters

  • Highland core encircled by semi-arid lowlands

  • Major rivers originate in these highlands, earning it the title of "Water Tower of East Africa"

Effects of Topography

Socio-Cultural and Economic Impacts

• Highland vs. Lowland:

  • Highlands:

    • Moderate-high rainfall (>600 mm/year)

    • Favorable climate for agriculture, densely populated

  • Lowlands:

    • Less rainfall and higher temperatures

    • Lower population density, nomadic lifestyles

    • Vast plains suitable for agriculture

Physiographic Divisions of Ethiopia

1. Western Highlands and Lowlands

2. South-Eastern Highlands and Lowlands

3. Rift Valley

The Western Highlands and Lowlands

• Area west of the Rift Valley, accounts for 44% of Ethiopia's land

• Features highlands (76.3%) and lowlands (23.7%)

Western Highlands

• Key Areas:

  • Tigray Plateau

  • North Central Massifs

  • Shewa Plateau/Central Highlands

  • Southwestern Highlands

Tigray Plateau

• Extends from Tekeze gorge to Eritrea; contains notable peaks above 3000 m

• Home to the Debre-Damo monastery

North Central Massifs

• Dominated by Lake Tana basin; contains significant peaks over 4000 m

• Historical connection via Yeju-Wadla Delanta land bridge

Shewa Plateau/Central Highlands

• Central location; drains into Abay, Omo, and Awash rivers

• Contains flat-topped uplands and significant agricultural advantages

Southwestern Highlands

• Most wet; drained by major rivers; significant biodiversity

• Guge Mountain as the highest peak

The Western Lowlands

• Foothills and plains, area characterized by arid conditions

• Limited agriculture; possibilities for irrigation

The Southeastern Highlands and Lowlands

• Second largest division, accounts for 37% of Ethiopia

• Features include Arsi-Bale-Sidama Highlands and Hararghe Plateau

The Rift Valley

• Tectonically formed; extends from Afar triangle to Chew Bahir

• Characterized by volcanic features and climatic variation

Afar Triangle

• Main area of Rift Valley, low altitude with harsh conditions

• Key economic activities include salt extraction

Main Ethiopian Rift

• Narrowest/highest section of Rift Valley; significant agricultural region

Chew Bahir Rift

• Broad marshy area; distinct ecological characteristics

Impact of Relief on Biophysical and Socioeconomic Conditions

1. Agriculture

• Influences farm size, shape, and crop types

2. Settlement Patterns

• Densely settled highlands vs sparsely populated lowlands

3. Transportation and Communication

• Rugged terrain hinders development, leads to isolation

4. Hydroelectric Power Potential

5. Socio-Cultural Diversity

6. Climate

7. Soil Quality

8. Natural Vegetation Types

Discussion Questions

• What are the impacts of relief on the biophysical and socioeconomic conditions of Ethiopia?

• Discuss the physiographic characteristics of the southeastern highlands and lowlands.

Conclusion

• Understanding topography is crucial for grasping the geographical, cultural, and economic complexities of Ethiopia.