This book focuses on regions for which until now the geomorphology was very poorly studied and relatively unknown. Nevertheless, the landforms and landscapes of the Horn of Africa are highly attractive, diverse and in a few cases unique, since they span very different environments, from highland plateaus and mountains to lowlands (even below sea level) and coastlines with a high degree of diversity and from monsoon to arid climate conditions.
The main topics addressed in the book include the links between the geological evolution and the current large scale geomorphology of the Horn of Africa; the large differences between the highlands and lowlands climate, river hydrology and their variation through time within a climate change perspective. This part of the world was home of the very first hominids. The landscape in which they lived and evolved throughout the Pleistocene is described in comparison with the arid and inhospitable, though immensely scenic, environment of today.
Perennial and ephemeral rivers with very different morphology, processes, and hydrology drain the area, and, in combination with the past and recent uplift, substantially contributed to provide the region with peculiar landscapes and landforms. Long lasting weathering and erosion processes result in a typical inselberg landscape such as the Bur region, or the currently exposed flatland of old peneplain surfaces. Their changes through time, induced by both natural and anthropogenic factors, are addressed by a couple of case studies. Though the region has few inhabitants, they had to struggle to find their livelihood in a land that offers poor resources. This resulted in landscape change and land degradation. Examples of human impact on the landscape are presented at different scales.
This book provides readers interested in geography and geomorphology with essential scientific and educational information on the Landscapes and Landforms of Eritrea, Djibouti and Somalia through simple, though scientifically, rigorous texts illustrated with several color maps and photos. One main prerogative of this book is therefore to give an insight into a region of the world where, for geographical and historical constraints, geomorphological investigation was very limited, thus enriching its intrinsic informative value.
Author(s): Paolo Billi
Series: World Geomorphological Landscapes
Publisher: Springer
Year: 2022
Language: English
Pages: 406
City: Cham
Series Editor Preface
Preface
Contents
About the Editor
1 Climate Variability in the Horn of Africa Eastern Countries: Eritrea, Djibouti, Somalia
Abstract
1.1 Introduction
1.2 Study Area, Data and Methods
1.2.1 Data Type and Sources
1.2.2 Data Processing Methods
1.3 General Climate and Atmospheric Circulation
1.4 Temperature
1.5 Precipitation
1.5.1 General Considerations
1.5.2 Rainfall Erosivity
1.6 Relative Humidity
1.7 Wind
1.8 Aridity and Desertification
1.9 Climate Change
1.9.1 Temperature Change
1.9.2 Precipitation Change
1.9.3 Rainfall Erosivity Change
1.9.4 Desertification Trends
1.10 Discussion
1.11 Conclusions
Acknowledgements
References
2 Geology and Geomorphological Landscapes of Eritrea
Abstract
2.1 Introduction
2.2 General Physiography: From Eritrea to Somalia
2.3 Geological Outline of Eritrea
2.3.1 The Neoproterozoic Basement
2.3.2 The Neoproterozoic and Paleozoic Glacial Episodes and Long Sediment Vacancies
2.3.3 A Rifted Gondwana and the Jurassic Sea
2.3.4 A Long Waiting Before the Volcanic Outburst: The Laterites
2.4 Syn-Rift Volcanic and Sedimentary Rocks on the Plateau and on the Lowland
2.4.1 Syn-Rift Successions on the Plateau
2.4.2 Syn-Rift Successions on the Lowland
2.4.3 Post-rift Successions and Events
2.5 The Physiographic Evolution of the Eritrean Plateau and Its Denudation Rate
2.6 Conclusions
Acknowledgements
References
3 Geomorphology of Afar
Abstract
3.1 Introduction
3.2 A Toponymy Expressing Landscapes and Landforms
3.3 Afar Margins
3.4 Afar Floor: The Basaltic Stratoid Series
3.5 Dominantly Silicic Stratovolcanoes of Afar Margins and MER Northern End
3.6 Transverse Basaltic Alignments
3.7 Axial Ranges (Active Rift Axis)
3.8 Sedimentary Plains and Lakes
3.9 Hydrothermal, Tectonic and Volcanic Activity; Geothermal Perspectives
3.10 Conclusion
References
4 Geomorphology of Eritrean River Systems
Abstract
4.1 Introduction
4.2 Study Area
4.3 Channel Morphology
4.4 Geological Structure and River Pattern
4.5 Longitudinal River Profile and Tectonics
4.5.1 Energy Gradient and Longitudinal Profile
4.5.2 Stream Gradient Index (SGI)
4.5.2.1 Plateau Rivers
4.5.2.2 Coastal Belt Rivers
4.6 Discussion
4.6.1 Channel Morphology
4.6.2 Channel Pattern and Profile
4.7 Concluding Remarks
Acknowledgements
References
5 Pleistocene Landscape Variability Recorded in the Homo-Bearing Dandiero Basin (Eritrea)
Abstract
5.1 Introduction
5.2 Geological Settings
5.3 The Basin-Fill Succession
5.3.1 Sedimentology and Magnetostratigraphy
5.3.2 Mammal Remains
5.4 Structural Geology
5.5 Discussion: Evolution of the Basin and Forcings on Landscape Transformations
5.6 Conclusions
References
6 Landscape and Landforms of the Samoti Plain, Eritrean Danakil
Abstract
6.1 Introduction
6.2 Study Area
6.3 Geomorphological Landscapes
6.3.1 Fluvial Geomorphology and Processes
6.3.2 Aeolian Geomorphology
6.4 Environmental Change
6.5 Concluding Remarks
References
7 Forest Landscape Evolution in Eritrea Throughout the Last Century—A Review
Abstract
7.1 Introduction
7.2 Geobotanical Features of Eritrea: An Overview
7.2.1 Botanical Explorations in Eritrea
7.2.2 Geobotanical Studies and Maps
7.2.3 The Mangrove Formations
7.3 Forest Cover and Soil Erosion
7.4 Discussion
7.4.1 The Consequences of Colonialism on the Forest Land
7.4.2 Reforestation and Landscape Protection
7.5 Conclusion
References
8 Landscape Change, Land Degradation, and Sustainable Land Management in the Central Highlands of Eritrea
Abstract
8.1 Introduction
8.2 Landscape Change: The History of Forest Cover and Current Afforestation Efforts in the Central Highlands of Eritrea
8.3 Land Degradation and the Promotion of Soil and Water Conservation
8.3.1 Soil and Water Conservation in the Highlands of Eritrea
8.3.2 Soil Conservation and Water Availability
8.3.3 Local Traditional or External International? Merits and Demerits of Different Conservation Approaches
8.3.4 Dam Construction and Sustainable Land Management
8.4 Concluding Remarks
References
9 Land Degradation in Eritrea and Djibouti
Abstract
9.1 Introduction
9.2 Results
9.2.1 Climate Data
9.2.2 Vegetation Data
9.2.3 Land Surface Erosivity
9.3 Discussion
9.4 Conclusions
References
10 Landscape and Landforms of Northern Somalia
Abstract
10.1 Introduction
10.2 Study Area
10.3 Landscape and Landforms of the Awdal Region
10.4 Landscape and Landforms of the Marodijeex Region
10.5 Sahil Region
10.6 The Eastern Regions of Somaliland
10.7 The Bosaso (Boossaso) Plain
10.8 Concluding Remarks
References
11 Inselberg Landscape of the Bur Area in Southern Somalia
Abstract
11.1 Introduction
11.2 Physiographic Features of the Region
11.3 Geological Background
11.4 Granitoid Petrology
11.5 Landforms and Geomorphological Processes
11.6 Diversity of Inselberg Morphology
11.7 Inselbergs and Geoarchaeology
11.8 Conclusions
References
12 Fluvial Landscape of the Dabaan Basin, Northern Somalia
Abstract
12.1 Introduction
12.2 Study Area
12.2.1 Climate
12.2.2 The Rivers
12.3 Channel Morphology, Bedforms and Sedimentary Structures
12.3.1 Channel Morphology
12.3.2 Sediment
12.3.3 Bedforms
12.3.4 Sedimentary Structures
12.4 Concluding Remarks
References
13 River Hydromorphology and Flood Hazard in Somalia
Abstract
13.1 Introduction
13.2 Geographic Setting
13.2.1 Climate
13.2.2 River Hydrology
13.3 River Morphology
13.4 Flooding
13.4.1 Human Impact on Flooding
13.5 Discussion
13.5.1 Channel Changes
13.5.2 Increased Risk of Flooding
13.6 Conclusions
Acknowledgements
References
14 Recent Landscape Change in Somalia Monitored Through the Use of Repeat Photography
Abstract
14.1 Introduction
14.2 Data and Methods
14.2.1 Sources of Archival Aerial Photography and Mosaics
14.2.2 Baseline Sources on Natural Resources Assessment
14.3 Agricultural Development in the Inter-Riverine and Mudug
14.3.1 Cycles of Drought and Flood
14.3.2 Development Project Assessments in Southern Somalia
14.3.2.1 Physical Setting from the Inter-Riverine to Northern Somalia
14.3.2.2 Development Projects
14.4 Case Study: Irrigation Designs at Luuq and Jalalaqsi
14.4.1 Background
14.4.2 Juba at Luuq
14.4.3 Shabelle at Jalalaqsi
14.4.4 Conclusions
14.5 Case Study: Flood Damage Study of the Juba and Shabelle Inter-Riverine
14.5.1 Background
14.5.2 Remote Sensing Methods
14.5.3 Assessments on the Shabelle
14.5.4 Assessments on the Juba
14.5.5 Conclusion
14.6 Case Study: Land Evaluation at Farjano
14.6.1 Background and Purpose of the Project
14.6.2 Assessments and Present Situation
14.6.3 Conclusions
14.7 Case Study: Assessment of Forest Ecology Along Middle Juba
14.7.1 Survey of the Forests in 1986
14.7.2 Present Status
14.7.3 Conclusions
14.8 Case Study: Observations on the Coastal Dunes and Northern Escarpment
14.8.1 The Old Red Sandridge
14.8.2 Dust Hot Spots
14.8.3 Northern Escarpment
14.8.4 Conclusions
14.9 Case Study: Soil and Water Conservation and Vegetation Arcs in Somalia
14.9.1 Background
14.9.2 Arabsiyo Valley Soil and Water Conservation, 1963–64
14.9.3 Vegetation Arc and Water Harvesting in Somalia
14.10 Conclusions
14.10.1 Water Harvesting
14.10.2 Vegetation Arcs of Somalia and the Ogaden
14.10.3 Northern Escarpment
14.10.4 Use of Archival Materials
Acknowledgements
References
Index
