Grade 9 Geography Textbook - Ethiopia

GEOGRAPHY GEOGRAPHY GEOGRAPHY STUDENT TEXTBOOK STUDENT TEXTBOOK 9...

GEOGRAPHY GEOGRAPHY GEOGRAPHY STUDENT TEXTBOOK STUDENT TEXTBOOK 9 STUDENT TEXTBOOK GRADE 9 GRADE GRADE 9 FEDERAL DEMOCRATIC REPUBLIC OF ETHIOPIA MINISTRY OF EDUCATION Take Good Care of Th is Textbook This textbook is the property of your school. Take good care not to damage or lose it. Here are 10 ideas that help you take care of the book: 1. Cover the book with protective materials. 2. Always keep the book in a clean dry place. 3. Be sure your hands are clean when you use the book. 4. Do not write on the cover or inside pages. 5. Use a piece of paper or cardboard as a bookmark. 6. Never tear or cut out any pictures or pages. 7. Repair any torn pages with paste or tape. 8. Pack the book carefully when you place it in your school bag. 9. Handle the book with care when passing it to another person. 10. When using a new book for the first time, lay it on its back. Open only a few pages at a time. Press lightly along the bound edge as you turn the pages. This will keep the cover in good condition.  GEOGRAPHY STUDENT TEXTBOOK GRADE 9 Writers: Muluemebet Worku (Ph.D) Kidanemariam Paulos (Ph.D.) Editors: Sintayehu Teka (M.Sc.) (Content Editor) Kassie Molla (M.A.) (Language Editor) Hirut Woldemichael (M.A.) (Curriculum Editor) Illustrator Agenchw Nega (M.Sc.) Designer Geda Hoka (M.A.) Evaluators Tesfaye Shiferaw (PhD) Abebe Yibeltie (MA) Hussein Seid (MA) FDRE, MINISTRY OF EDUCATION HAWASSA UNIVERSITY First Published August 2023 by the Federal Democratic Republic of Ethiopia, Ministry of Education, under the General Education Quality Improvement Program for Equity (GEQIP-E) supported by the World Bank, UK’s Department for International Development/ DFID-now merged with the Foreign, Common wealth and Development Office/FCDO, Finland Ministry for Foreign Affairs, the Royal Norwegian Embassy, United Nations Children’s Fund/UNICEF), the Global Partnership for Education (GPE), and Danish Ministry of Foreign Affairs, through a Multi Donor Trust Fund. ©2023 by the Federal Democratic Republic of Ethiopia, Ministry of Education. All rights reserved. The moral rights of the author have been asserted. No part of this textbook reproduced, copied in a retrieval system or transmitted in any form or by any means including electronic, mechanical, magnetic, photocopying, recording or otherwise, without the prior written permission of the Ministry of Education or licensing in accordance with the Federal Democratic Republic of Ethiopia as expressed in the Federal Negarit Gazeta, Proclamation No. 410/2004 - Copyright and Neighboring Rights Protection. The Ministry of Education wishes to thank the many individuals, groups and other bodies involved – directly or indirectly – in publishing this Textbook. Special thanks are due to Hawassa University for their huge contribution in the development of this textbook in collaboration with Addis Ababa University, Bahir Dar University and Jimma University. Copyrighted materials used by permission of their owners. If you are the owner of copyrighted material not cited or improperly cited, please contact the Ministry of Education, Head Office, Arat Kilo, (P.O.Box 1367), Addis Ababa Ethiopia. Printed by: GRAVITY GROUP IND LLC P.O.Box 13TH Industrial Area, Sharjah UNITED ARAB EMIRATES Under Ministry of Education Contract no. MOE/GEQIP-E/LICB/G-01/23 ISBN: 978-99990-0-048-2  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE UNIT ONE 1. GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA INTRODUCTION As you remember, in grade eight you learnt about the physical characteristics of the Earth, people and socioeconomic activities, natural resources and socioeconomic development, modern history of Ethiopia and contemporary global issues. In this grade you are going to study about the geography of Ethiopia. This textbook comprises the physical, human and economic environment of the country. Subsequently, you will learn about the country’s location, size, shape, geological history, topography, drainage, climate, vegetation, wildlife, soil, mineral resources, major economic activities and human-natural environment interactions. In addition, the major topics to be covered also include the geographic enquiry, skills and techniques. Before you start studying the above mentioned geographical themes, you will be acquainted with some basic concepts related to the science of geography hereunder. These concepts include the meaning, scope and branches of geography. 1  Grade 9| Geography Unit Outcomes After completing this unit, you will be able to: ✅ recognize the concept, scope and branches of geography; ✅ express the basic land features of the physical environment; ✅ describe the absolute and relative location of Ethiopia; ✅ analyze the effects of shape and size of Ethiopia on its sociocultural, political and economic condition; ✅ explain geologic processes that shaped the land surface of Ethiopia; and ✅ describe the different landforms of Ethiopia. Main Contents 1.1 Geography: Meaning, scope and branch 1.2 Location, size, and shape of Ethiopia 1.3 Geological history of Ethiopia 🌐 Unit Summary 🌐 Review Exercise 1.1 GEOGRAPHY: MEANING, SCOPE AND BRANCHES At the end of this section, you will be able to: ✅ define geography as a subject; ✅ describe the scope of geography; and ✅ 🔒 identify the branches of geography. KEY TERMS 🔑 Geography 🔑 Physical geography 🔑 Human geography 🔑 Spatial 2  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE 1.1.1 Meaning of Geography What is geography? Do you think geography has a single universally accepted definition? If not, why? The term “Geography” first appeared in history at the time when the Greek civilization reached its peak. They defined geography for the first time by combining two words of Greek origin namely: Geo and Graphos. → Geo – which means earth → Graphos – which means writing Eratosthenes, a famous Greek Philosopher (276-194 B.C) coined the term Geography and defined it as “the field of study that deals with the description of the earth”. Now this definition seems very general when we compare it to the scope of current geography. A number of definitions have been given by different scholars of the nineteenth and twentieth centuries. These definitions relate to geography’s current concerns, interests and focus. Here are some of the most important definitions that scholars have proposed: Þ Eratosthenes (276-196 BC) – Geography is the description of the earth. Þ Alexander Von Humboldt (1769-1859) - Geography is a synthesizing discipline to connect the general with the particular through measurement, mapping, and a regional emphasis. Þ Concise Oxford Dictionary (1964) - Geography is the science of the earth’s surfaces. Þ Hartshorne, R. (1899-1992) – Geography is a branch of knowledge that is concerned with the provision of an accurate, orderly and rational description of distributions on the surface of the earth. Þ Yeates, M. (1968) – Geography is a science that is concerned with the rational development and testing of theories that explain and predict the spatial distribution and locations of things and phenomena on the surface of the earth. As you have read above, each of these definitions includes the idea that geography studies the earth. Most of them specify the surface of the earth. 3  Grade 9| Geography It is difficult to forward a definition acceptable to all geographers at all times and places because of the dynamic nature of the discipline and the changes in its scope and method of study. However, the following may be widely accepted definitions by most scholars. Geography is the scientific study of the Earth that describes and analyses spatial and temporal variations of physical, biological and human phenomena, and their interrelationships and dynamism over the surface of the Earth. 1.1.2 The Scope of Geography What does the word scope mean? What is the scope of geography? Scope refers to the content (how broad or narrow) of the field of study of a given discipline, in this case geography. The scope of Geography is very wide. As the scope is dynamic, it often changes as discoveries and ideas enter the field. Geography studies a great many physical and human features of the world. Its focus includes their causes, effects, and interactions. As a result, the subjects that geography examines include features in the hydrosphere, atmosphere, lithosphere, biosphere and anthroposphere. Geography as a field of study is also concerned with the economic, social, political and ecological problems that you hear every day. It is also concerned with modern technology, such as computers, Global Positioning System (GPS) and Geographic Information System (GIS) to analyze information and draw conclusion with accuracy. NOTE Þ Hydrosphere – it includes all the bodies of water, i.e., oceans, rivers, lakes and others. Þ Biosphere – refers to all living organisms in and on the earth’s surface. Þ Atmosphere – it includes all aspects of air composition surrounding our planet. Þ Lithosphere – it is the solid layer of rocks that covers the entire surface of the planet. Þ Anthroposphere – it is the part of the environment that is made or modified by humans. 4  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE Did you notice how wide the scope of geography is? Do you understand the extent of its scope? It is true that geography has a very wide scope. However, this does not mean its scope is limitless. The major areas that geography focuses on are: Þ the earth, its position in the universe and its movements; Þ the different physical features that constitute the earth’s surface, the forces that cause them, their variations from place to place and their changes over time; Þ the different relationships between human beings and their natural environment. Also, the interdependence and the impact that each has on the other; Þ the conditions of the lower part of the atmosphere and the subsequent weather and climatic conditions, together with their spatial distribution and variation; Þ the materials that make up the earth and its diverse landforms; and Þ the major economic activities of humans and the impacts on the environment. Therefore, geography deals with an enormous range of phenomena ranging from physical and biotic to human environment. It is possible to conclude that although wide in its scope, geography has certain areas that it focuses upon. Hence, geography is a holistic discipline of knowledge and research (academics). 1.1.3 Branches of Geography What are the two branches of geography? Can you list some of the fields of geography that fall into each of the two branches? You have studied the definition of geography, and you have considered its scope. Next, you will learn about the main parts of geography and its sub-branches. The two main parts are: Þ physical geography; and Þ human geography 5  Grade 9| Geography A. Physical Geography What does physical geography study? Do you know the sub- branches of physical geography? Physical geography studies the distribution of the natural features of the world, such as climate, landforms, soil, vegetation, surface drainage systems, water resources and animals. This branch of geography also considers the causes, effects and interactions of these features. Physical geography is further sub-divided into more specialized fields of study as follows: Physical geography Geomorphology Climatology Biogeography Oceanography Soil geography Phytogeography Zoogeography 6  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE B. Human Geography What does human geography study? Do you know the sub-branches of human geography? Human geography studies the distribution and influence of human aspects of our world, including cultures, population settlement, economic activities and political systems. This branch of geography is sub-divided into the following specialized fields of study. Human Geography Cultural Population Economic Political Urban Historical Geography Geography Geography Geography Geography Geography 7  Grade 9| Geography Activity 1.1 Discuss the following questions in small groups. 1. Geography studies the spatial distribution of phenomena on the earth’s surface on one hand and the two-way interactions and interdependences between humankind and the environment on the other. Do you agree or disagree to this statement? Why? 2. Some people say geography is concerned only with the study of place names. Do you agree or disagree to such idea? Why? 3. Do you think that the scope of geography is limitless? Why or why not? 4. What are the major areas of the study of geography? 1.2 LOCATION, SIZE AND SHAPE OF ETHIOPIA At the end of this section, you will be able to: ✅ describe the absolute and relative location of Ethiopia; and ✅ discuss the effects of size and shape of Ethiopia on its sociocultural, political and 🔒 economic contition. KEY TERMS 🔑 Absolute location 🔑 Latitude 🔑 Compact shape 🔑 Longitude 🔑 Elongated shape 🔑 Relative location 🔑 Strategic location 🔑 Vicinal location 1.2.1 Location of Ethiopia Why is the location of things important in geography? What locational significance does Ethiopia have as a country that is in the Horn and near the Red sea route? A location is a place where a particular point or object exists. In spatial distribution, every place has its own particular location in relation to its surroundings. 8  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE In geography, the term location is a much more abstract concept than what an ordinary person knows. This important term is usually expressed in two ways: relative location and absolute location. A. Relative Location of Ethiopia Can you identify the relative location of your school or residence? Relative location refers to the position of a place in relation to the location of other geographic features. Relative location can be expressed in the following two ways; namely; vicinal location and geological location. Vicinal location shows the location of a country in relation to neighboring countries (Table. 1.1), while the strategic also known as natural location describes a country’s location in reference to water bodies and landmasses. i. Vicinal Location of Ethiopia Ethiopia is a landlocked country that is surrounded by six neighboring countries (see Fig 1.1). Each country shares different lengths of Ethiopia’s borderlines. The total length of Ethiopia’s boundary line is 5,260 km. Table 1.1: Ethiopia’s Boundary Line length as Shared with Neighboring Countries SN Bordering Shared Boundary Ethiopia is found; Countries Length in Km 1 Djibouti 310 West of Djibouti 2 Eritrea 840 South of Eritrea 3 Kenya 760 North of Kenya 4 Somalia 1,600 West and Northwest of Somalia 5 Sudan 744 East and Southeast of Sudan 6 South Sudan 1,006 Northeast of South Sudan Total 5,260 Table 1.1 indicates that Ethiopia shares the longest length of boundary line with Somalia while the Republic of Djibouti shares the smallest boundary line length. 9  Grade 9| Geography Figure 1.1: Relative Location of Ethiopia ii. Strategic Location of Ethiopia Strategic location is also called natural or global location. Consequently, Ethiopia’s strategical location can be described in the following ways. It is found: Þ in northeastern (Horn) Africa; Þ to the southwest of the Asian continent; Þ in the Nile Basin; Þ to the south of Europe; Þ to the northwest of the Indian Ocean; Þ to the southwest of the Red Sea; and Þ to the south of the Mediterranean Sea. B. Absolute or Astronomical Location of Ethiopia How do we know the exact position of Ethiopia on the earth’s surface? Can you describe the absolute location of Ethiopia? Absolute location is expressed as a geographical extent, in terms of latitudes and longitudes. The absolute location of Ethiopia is expressed as follows. Ethiopia is located between 3oN – 15oN latitudes and 33oE– 48oE longitudes 10  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE As a result, Ethiopia’s extreme points lie at: Þ the Northern tip of Tigray in the north; Þ Moyalle in the south (Borena); Þ Akobo in the west (Gambella) and Þ the tip of Ogaden in the east (Ogaden) ( see Fig.1.2). Figure 1.2: Absolute Location of Ethiopia 1.2.2 Size of Ethiopia How big is Ethiopia areally and what are the effects of its size? Ethiopia is the tenth largest country in Africa, with a total area of 1,106,000 square kilometers. It contains about 0.7 percent of the world’s land area and about 3.6 percent of Africa’s land mass. Table 1.2: Comparison of Ethiopia’s Areal Size with its Neighbors Country Total area (in sq.kms) Rank Size in comparison to Ethiopia Ethiopia 1,106,000 2 − Sudan 1,849,233 1 1.01 times bigger Somalia 637,661 3 1.73 times smaller Kenya 580,000 5 1.91 times smaller Eritrea 118,000 6 9.42 times smaller Djibouti 23,200 7 Almost 50 times smaller South Sudan 631,928 4 1.75 times smaller Source: CSA, 2012 11  Grade 9| Geography NOTE The Horn of Africa takes its name from the horn-shaped land formation that forms the easternmost point of the African continent, projecting into the Indian Ocean south of the Arabian Peninsula. Ethiopia is the largest country in the Horn. This status in size, in combination with its status of having a large population, confers many advantages to Ethiopia in the Horn area. What advantages and disadvantages does Ethiopia’s large size offer the country? Advantages: Ethiopia’s large size lets it: Þ enjoy diverse agro-ecological zones, resulting in a wide variety of fauna and flora; Þ possess a large amount of arable land; Þ have a great variety of mineral resources; and Þ be the home of diverse ethnic groups. Disadvantages: Its large size forces Ethiopia to: Þ require expensive administrative expenditure; Þ have a large army to protect its sovereignty; Þ require great financial power to construct infrastructural facilities; and Þ face challenges for effective administration and socio-economic integration. 1.2.3 Shape of Ethiopia Look at the shape of Ethiopia and the neighboring countries. Does Ethiopia have similar shape with its neighboring countries? Can you identify the shape of each neighboring countries? Countries of Africa and the world at large vary not only in location and size but also in shape. Some countries have nearly circular (compact) shapes, others have elongated (linear) shapes, and still others have truncated (shortened) shapes. These shapes have implications on the administrative, defense and economic integration, both within the country and with respect to outside areas. 12  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE When you compare the shape of Ethiopia with the other countries, you find that Ethiopia has more or less compact (circular) shape. Its shape is considered to be compact or essentially circular because the extreme north-south and east-west spans of the country cover comparable distances. You can easily see this approximate circularity in your school atlases and wall maps. There are three theoretical indicators of the compactness of an area: Þ the boundary - circumference ratio (B/C); Þ the area - boundary ratio (A/B); and Þ the actual area - area of the inscribing circle (A/A’). NOTE Each of these theoretical assumptions is based on a value of 1 as indicating a perfectly compact shape except A/B ratio. They consider 0.5 –1.5 values as deviating only slightly from circular/compact and therefore indicating approximate compactness. In contrast, smaller values indicate greater divergence from compactness, especially as they approach zero (0). These small values reflect tendencies to elongation or truncation. On the other hand, A/B ratio compares the total area of a country under consideration with the total boundary length of the same country. The larger the areal size per unit boundary length is, the more compact the country is. For example, let’s use the boundary-circumference ratio to measure Ethiopia’s degree of compactness or index of compactness. In the ratio, circumference is based on the assumption of a circle having equal area with the country under consideration. The formula to find the circumference of a circle having equal areal size as the country under consideration is 2πr (π=3.14 ). The value of radius (r) is not given, and it should be computed. It is going to be calculated taking an area of a circle that is assumed to have equal areal size as the country under consideration.. Thus, area of the circle is calculated taking the following formula (i.e. A=πr2). 13  Grade 9| Geography Example The B/C ratio of Ethiopia can be calculated as follows: Given Solution:  The total boundary length of C=2πr , The value of π is 3.14, while Ethiopia: = 5260Kms the value of “r” is derived from the circle  Circumference of a circle whose area is equal to Ethiopia’s area (i.e., having an area similar to area 1,106,000Km2). of Ethiopia (=1,106,000Km2). πr2 = 1,106,000Km r2= 352,229.3 Hence, r= 593.5 Kms Therefore, C= 2πr Circumference of area of Ethiopia (if it were circle) =2 x 3.14 x 593.5 = 3727.18 B/C ratio of Ethiopia = 5260/3727.18 = 1.411 This value implies that the shape of Ethiopia has a deviation of 41% from the assumed theoretical circular shape it ought to have. The compact shape has militaristic advantage as stated earlier. This can be well explained by considering an area and borderline length ratio. The index of compactness using A/B ratio for Ethiopia is indicated hereunder. What does this ratio imply? Þ It implies that if 1 km borderline is safeguarded by national army, 210 km2 of the hinterland will become free from the assault of an enemy. Another way of estimating the compactness of shape of any country is considering the ratio of area of the country to the area of the smallest inscribing circle. In the ratio, area the circle is based on the assumption of smallest inscribing circle that touches the north, south, east and west boundaries of Ethiopia described earlier in the “Absolute Location” section. 14  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE The ratio of actual area to the area of the smallest inscribing circle (A/A’) for Ethiopia can be calculated using the following formula: N.B. Lower value near 0 indicates elongation and a higher value near 1 suggests more compactness. Activity 1.2 Answer the following questions 1. Use a world map or atlas and identify places that are in the following positions: 3oN – 15oN & 33oE– 48oE 2. In small groups, discuss the advantages and disadvantages of the Ethiopia's large size. 1.3 GEOLOGICAL HISTORY OF ETHIOPIA At the end of this section, you will be able to: ✅ explain the geological history of Ethiopia; ✅ distinguish the geological processes that result in the current landform of Ethiopia; and ✅ describe major landforms of Ethiopia. 🔑 Endogenic force 🔒 KEY TERMS 🔑 Exogenic force 🔑 Regression 🔑 Epeirogenic 🔑 Geology 🔑 Relief 🔑 Epoch 🔑 Orogenic 🔑 Transgression 🔑 Era 🔑 Period 15  Grade 9| Geography 1.3.1 The Geological Processes in Ethiopia Which geological era is significant regarding the formation of the various landforms in Ethiopia? The geological history of Ethiopia is part of the geological processes that acted within and upon the earth’s surface for many millions of years in the past. To describe the geology and history of life on Earth, scientists have developed the geological time scale. The geological time scale measures time on a scale involving four major geological eras. Each era is divided into periods, the periods into epochs, epochs into years and years into major occurrences. Each geological era is distinguished from the others based on grounds of the following three characteristics: Þ the relative positions of the continents; Þ the character of the prevailing climate; and Þ the predominant lifeform (plants and animals). Summary of Major Geological Events in the Horn Let’s begin by considering the different geological eras and then study the events that took place in those eras. Here are the geological eras, in chronological order.  The Precambrian Era – the oldest era (from 4.5 billion years to 600 million years ago.  The Paleozoic Era (from 600 million years to 250 million years ago).  The Mesozoic Era (from 250 million years to 70 million years ago).  The Cenozoic era (from 70 million years to the recent time). I. The Precambria Era (from 4.5 Billion to 600 Million years ago). What do you understand by the term Precambrian? The Precambrian Era is the oldest and longest geological era, covering about 5/6 of the earth’s geological time. The following geological events occurred in the Horn during this era. Þ Frequent orogenic movements (mountain building process by volcanic eruptions); Þ Intensive volcanic activities; 16  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE Þ Denudation during the later periods (reduction or wearing down of the mountains); and Þ Formation of folded mountain. NOTE During the Precambrian era: Þ The first forms of life (one-celled) emerged, such as amoeba, and jellyfish, and Þ The oldest rock formed – the old crystalline basement/ basement complex rock. This rock is found beneath all other rocks. Today, in a few areas of Ethiopia, outcrops of old crystalline basement complex rocks are found on the surface, due to continuous denudation. Example: Þ In central and northern Tigray; Þ In Mettekel, Assossa, Illubabor and the Abbay Gorge; Þ In central Sidama, southern Omo, southern Bale and Borena, and Þ In central, western and northern Eritrea. Figure 1.3: Geological Map of Ethiopia 17  Grade 9| Geography II. The Paleozoic Era (from 600 million years to 250 million years ago) Which life form was dominant in the Paleozoic era? During this era, in Ethiopia, the major geologic (geomorphic) process was denudation followed by peneplanation. No significant structural formation took place. Hence, the Paleozoic is the only era that left a gap in a rock formation in Ethiopia. The massive denudational activity resulted in the formation of inselbergs (residual features) in some parts of Ethiopia. NOTE The Paleozoic era is known for the predominance of invertebrates. III. The Mesozoic Era (from 250 million years to 70 million years ago) Which life form was dominant in the Mesozoic era? This era was marked by alternate slow sinking and uplifting of the landmass (Epeirogenesis) of the Horn of Africa. The Mesozoic Era was an era of sedimentary rock formation in Ethiopia. The Mesozoic era has three distinct periods as indicated hereunder. Table 1.3 The Three Periods of Mesozoic Era Periods Geological time scale Triassic 250 - 180 millions Jurassic 180 - 135 millions Cretaceous 135 - 70 millions Triassic Period During this Period, the landmass sank due to internal forces. This event was followed by transgression of a nearby sea into the mainland of today’s Somalia and southeastern Ethiopia. During the Triassic Period, the oldest sedimentary rock known as Adigrat sandstone was formed. The Adigrat sandstone is the oldest in the southeast and progressively decreases in age to the northwest. 18  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE Jurassic Period In this Period, the transgression of the sea continued into the mainland in the northwest direction. This event deposited another sedimentary rock known as Hintalo limestone. The Hintalo limestone in the northwest is younger while it is older in the southeast. Cretaceous Period During this period, the landmass began to rise and the sea started to regress towards the southeast, depositing sedimentary rock known as Upper Sandstone. Upper Sandstone is the youngest sedimentary rock and therefore overlies the rest. Because of the direction of the regression and deposition, Upper Sandstone is the youngest in the southeast, and it is the oldest in the northwest. NOTE The transgression of the sea extended up to northwestern Ethiopia, as far as central Tigray and the western slopes of the western highlands. The sedimentary rocks formed in the Mesozoic Era were later buried by overlying Cenozoic igneous rocks. However, the sedimentary rocks have been exposed at the surface in some areas of Ethiopia. They are thinnest (because they are the youngest) in the southeast and thickest (because they are the oldest) in the northwest. One can see them exposed at the surface mostly in the southeastern lowlands of Ethiopia, central Tigray, and in the Abbay and Wabishebelle gorges. (For more information, look at the geological map of Ethiopia.) The Mesozoic is also known for the predominance of reptiles. Huge reptiles, such as dinosaurs, were dominant. However, at the end of this era, two other significant biological events occurred: Þ one was the disappearance of the dinosaurs, and Þ the other was the emergence of mammals, birds and flowering plants. 19  Grade 9| Geography IV. The Cenozoic Era (from 70 million years to the recent time) Do you know the era in which the Great East African rift valley was formed? It is the most recent geological era. During this era very significant structural, climatic and biological events have occurred in Ethiopia. Thus, geologic events of the Cenozoic era have greatly resulted in the development of very recent landforms in the Horn of Africa in general and Ethiopia in particular. The Cenozoic Era is divided into two periods namely, Tertiary and Quaternary. To make this lesson simple and comprehendible, we shall discuss only the geological events of this era into events of each of the Periods. a. Geologic Events of the Tertiary Period - (70 million - 2 million years ago) In the Tertiary Period, the uplifting that began in the Cretaceous Period of the Mesozoic Era continued and reached its maximum height. In Ethiopia and the Horn it formed huge blocks of dome over the greater part of the region. As the uplifting continued through time, great cracks opened in the crust and resulted in the pouring out of extensive basaltic lava (known as the Trappean lava series). The lava resulted in the formation of: Þ the Northwestern Highlands, Þ the Southeastern Highlands, and Þ the Somali plateaus. As the cracking and faulting continued during the period, it formed the Great East African Rift Valley System – of which the Ethiopian Rift Valley System is part. The Great East African Rift system extends from Palestine-Jordan in the north to Malawi-Mozambique in the south, for a distance of about 7,200 kilometers. Of these, 5,600 kilometers is in Africa, and 1,700 kilometers in Eritrea and Ethiopia. b. Geologic Events of the Quaternary Period (2 million - recent years) This period is known for its recent volcanic activities that took place after the formation of the Rift Valley. 20  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE In the Quaternary Period, the structures which were formed in Ethiopia and the Horn are: Þ the Afar Horst that extends into Djibouti, Þ the active volcano of Ertalle in Afar, Þ the dormant volcanic mountain of Fentalle in Eastern Oromia, Þ the extensive lava field and sheets of Metahara, Þ thermal springs and fumeroles of the rift valley, and Þ the Pluvial rainfall in Africa and the resultant deposition that took place in the lowlands of Ethiopia including the Rift Valley. NOTE The Cenozoic Era in its Quaternary Period is assumed to be the period in which modern man evolved. Activity 1.3. Answer the following questions 1. What was the noticeable geological event of the Precambrian era in Ethiopia? 2. List the most important sedimentary rocks ever formed in Ethiopia during the Mesozoic era? 3. When was the Ethiopian rift valley formed? 4. By looking at a geological map of Ethiopia, identify the areas where these rocks are found on the surface as outcrops: a) Metamorphic rocks b) Sedimentary rocks c) Quaternary lava deposits 1.3.2 Landforms of Ethiopia Have you had opportunities to travel to the different regions of Ethiopia? If you have, what did you notice along your routes? Landform refers to individual earth surface features. As mentioned earlier sub- section, the landforms of Ethiopia are largely the result of the Cenozoic era’s tectonic and volcanic activities. Consequently, they are characterized by great diversity of highlands, plateaus, ambas, and rugged mountains, deep river gorges and lowlands. 21  Grade 9| Geography Altitude varies from about 116 meters below mean sea level at the Dallol depression (Kobar sink) to 4620 m above mean sea level (a.m.s.l.) at Ras Dashen in the Semein mountain system. Between these extreme points lie a number of mountains. If 1000 meters is chosen as a demarcating contour line between highlands and lowlands, 56 percent of Ethiopia’s land is highland. This fact has given Ethiopia the name “Roof of Eastern Africa.” It is the only country in the region with such a high proportion of elevated surface. This elevated surface is bisected diagonally by the Rift Valley which extends from Syria to Mozambique across the East African lakes. Figure 1.4. Topography of Ethiopia These landforms are the results of two opposite forces: Þ the endogenic force that originates from inside the earth. For example, volcanic activity and tectonic forces, and Þ the exogenic force that originates at the surface (denudation and penepalantion). It is a combination of these two forces that created the existing landforms of Ethiopia. 22  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE In terms of the geological and structural features that resulted from the two types of forces, the relief of Ethiopia can be divided into three main physiographic divisions (see Figure 1.4): I. The Western Highlands and Associated Lowlands II. The Southeastern Highlands and Associated Lowlands III. The Rift Valley Figure 1.5.: Ethiopian’ Main Topographic Regions I. The western Highlands and Associated Lowlands 23  Grade 9| Geography A. The Western Highlands Have you ever had a chance to go to Bahrdar, Gondar, Mekelle, etc.? The Western Highlands stretches from Tigray in the north to the highlands of Gamo and Goffa in southwest. They are separated from the southeastern highlands by the Rift Valley. It is the biggest physiographic region. It makes up 44% of the area of the country ( see Fig 1.5). The Western Highlands are the source of a large number of rivers and streams. Famous rivers like Abbay, Baro and Tekezze emerge from these highlands. As the rivers are cross boundary, they influence Ethiopia’s geopolitics role in north eastern Africa and the Middle East. Based on the internal altitudinal variability, the region is further sub-divided into four groups of highlands. a) The Plateau of Tigray b) The North Central Massif c) The Plateau of Shewa d) The Southwestern Highlands a. The Plateau of Tigray Can you mention known mountain peaks in plateau of Tigray? The Tigrean plateau is the most northerly group of plateau bounded in the north by the Mereb River and in the south by the Tekezze river. It is drained by Mereb and the tributaries of the Tekezze. It is an area composed largely of sandstones and limestones, as the overlying basalt has been eroded. As a result, the soils are poor and thin. The plateau has been exposed to severe erosion due to long periods of human inhabitation. There are very high mountains on this plateau with elevations of over 3000 meters above sea level. Three of these are: Known mountain peaks on this sub-division include: Þ Mount Tsibet – 3988 m a.m.s.l. Þ Mount Ambalage – 3291 m a.m.s.l. Þ Mount Assimba – 3248 m a.m.s.l. 24  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE b. The North Central Massif What makes the Northern central Massif distinct from the Massif of central Ethiopia? The north central Massif are found between the Abbay Gorge in the south and the Tekezze Gorge in the North. This massif contains the highlands of Gondar, Gojjam and Wollo. River Abbay and Tekezze along with their tributaries have formed a number of gorges and steep sided river valleys. The north central Massif are the most rugged and dissected plateaus of Ethiopia. They are capped by basalts of the tertiary period and surrounded by deep gorges. Within each of the plateaus are small arable lands known as ambas. The ambas are isolated from one another by gorges. The Mountain systems in Gondar and Gojjam are separated from the eastern group of mountains in Wollo by impenetrable and deep gorges. At one point though, they are connected by Yeju-Wadla Delanta land bridge (ridge). The western Massif make up the Massif of South Gondar (Semein), while the eastern ones make up the Lasta and Wollo Massif. South of these is found the Gojjam Massif. The Gojjam Massif is the most extended tableland and is comparatively less dissected. It is formed on the core of the Amedamit-Choke mountains. It is carved by the Abbay river that effectively separated it from the Shewa plateau in the south and the Amhara Saynt Massif in the northeast. The North-Central Massif are known for the production of cereals, such as teff, pulses and oil seeds. Known mountain peaks in this Massif are: Þ Mount Ras Dashen – 4620 m a.m.s.l., Þ Mount Legeda – 4532 m a.m.s.l., Þ Mount Analu – 4480 m a.m.s.l., Þ Mount Tefaw Lezer – 4456 m a.m.s.l., Þ Mount Kolo – 4300 m a.m.s.l., Þ Mount Guna – 4231 m a.m.s.l., Þ Mount Abuna Yoseph – 4190 m a.m.s.l., and Þ Mount Hey – 4154 m a.m.s.l. C. The Plateau of Shewa (Central Plateau) Have you ever had the opportunity to travel from your locality to nearby plateau? If yes, what do you recognize all the way through until you reach any gorge? 25  Grade 9| Geography The Shewan Plateau is the smallest sub-division of the western highlands. It is a dome-shaped plateau that serves as a watershed between the Awash, Omo- Gibe and Abbay River basins. It extends westwards into western Wollega through Horo Guduru and forms a crescent shape which causes the Abbay to swerve and drain northwards. The Shewan plateau is separated from: Þ the plateau of Gojjam by the Abbay gorge in the north; Þ the southeastern highlands by the Awash River and the Rift Valley, and Þ the Highlands of Kafa by the Gibe River. The Plateau of Shewa is drained by the tributaries of the Abbay River in the west and the Awash River in the east. Its high mountains are found on its northeastern and south eastern margins; they are: Þ Mount Abbuye Meda – 4000 m a.m.s.l., and Þ Mount Guraghe – 3721 m a.m.s.l. d. The Southwestern Highlands Which regional zones are found in the southwestern highlands of the Horn? The southwestern highlands lie south of the Abbay trough which is greatly eroded due to torrential rain that pours down in the area for almost all of the year. It is the wettest region of the country with a total average annual rainfall of above 1500 mm. They include the highland areas of Wollega, Illubabor, Jimma, Kafa and Gamo and Goffa. The region is drained: Þ Northwards, by the Dabus and Didesa tributaries of the Abbay River; Þ Westwards, by the headstreams of the Baro-Akobo River; Þ Southwards, by the Omo-Gibe River, which ends in Lake Turkana; and Þ Eastwards, by the right-bank tributaries of the Omo-Gibe (the Gojeb- Gibe River of Jimma Zone and Yem Special Woreda). The general elevation of these highlands is relatively low when compared to that of the Northern and Eastern Highlands. Only a few areas are above 2500 meters. 26  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE The highest points in the region are the: Þ Gamo-Konso Highlands, Þ Maji-Korma Highlands, Þ Dawuro-Konta Highlands, Þ Tullu Wallel, and Þ Benishangul mountain. Mount Gughe has the highest altitude: 4200 m a.m.s.l. It is found in the Gamo plateau. These highlands are well-known for the production of coffee, inset, spice production, timbering, rubber tree production, cattle, honey, maize and high percentage of forest cover. Activity 1.4 Answer the following questions. 1. List the four sub-divisions of western highlands. 2. Why are northern mountains highly rugged? B. The Western Lowlands The Western Lowlands extend from western Tigray in the north up to the southern Gamo and Goffa in the south, bordering the Sudan and South Sudan with a general elevation of 500-1000 m a.m.s.l. They are characterized by arid and semi- arid climate. The Baro-Akobo lowland is the wettest lowland compared to other lowlands of this physiographic division. That is why the rivers draining the region (particularly the Baro river) have almost a regular flow of water for much of the year. These lowlands of this physiographic region are sub-divided into: Þ the Tekezze and Angereb Lowlands, Þ the Abbay Dinder Lowlands, Þ the Baro-Akobo Lowlands, and Þ the Omo-Gibe Lowlands. 27  Grade 9| Geography The Tekezze and Angereb Lowlands are the most northerly lowlands, drained by Tekezze and Angereb. The Abbay Dinder Lowlands extend from south of Metema town up to the southern part of the Abbay River. Because of climatic hardship in most parts of these lowlands, the communities practice pastoralist and semi-pastoralist ways of life. However, there are notable towns, such as Humera, Kurmuk, Omedla and Metema that serve as business centers for the communities living along the Ethio-Sudanese border. II. The Southeastern Highlands and Associated Lowlands Can you propose what feature separates these highlands from the northwestern highlands? Which highlands are said to be the components of southeastern highlands of Ethiopia? This physiographic region is found to the southeast of the rift valley. This region is further divided into highland and lowland units. A. The Southeastern Highlands The Southeastern Highlands of Ethiopia include: a) the Hararghe plateaus, b) the Arsi plateau, c) the Bale Massif, and d) the Sidama highlands. Their formation is similar to that of the North and Southwestern Highlands and they are capped by basaltic rock. They are the main sources of the Wabe Shebelle and Genale rivers. They are bounded: Þ in the west, by the fault line of the Rift Valley; Þ in the east, by the Ogaden Lowlands; and Þ in the south by the Elkerie and Borena Lowlands. a. The Hararghe Plateaus The Plateau of Hararghe rises sharply from the fault line of the Rift Valley and extends gently to the east up to Jigjiga. After Jigjiga, a fall in elevation takes place, giving way to the Ogaden Lowlands. The Plateau is drained by the left-bank 28  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE tributaries of the Wabe Shebelle River. The basaltic rocks have been worn away, exposing limestones and earlier sedimentary rocks. The Hararge Plateau area and its foothills are significant producers of coffee, chat, sorghum and millet. The prominent mountain peaks include: Þ Mount Gara Muletta (3381 m a.m.s.l.), and Þ Mount Jebel Tita (3122 m a.m.s.l.). b. The Arsi Plateau This plateau area consists of the Gugu and Chillalo Massif. It is an extendingly rolling plateau; it is a very suitable plateau for farming. These features has been comparatively low because of the erosion on the Arsi plateau. The Arsi plateau is known for its wheat production. The highest points on the Arsi plateau are: Þ Mount Chillallo (4136 m a.m.s.l.), Þ Mount Bada (4139 m a.m.s.l.), and Þ Mount Kaka (4180 m a.m.s.l.). c. The Bale Massif The Bale Massif is next to the Arsi Plateau but is separated from it by the headstreams of the Wabe Shebelle, popularly known as the Wabe River. In the north, the massif consists of a flat form that is similar to basaltic plateaus. The Bale massif is known for its barely. In its southern part, the massif consists of huge mountains. The highest points on the Bale Mountains are: Þ Mount Tulu Dimtu (4377 m a.m.s.l.), and Þ Mount Batu (4307 m a.m.s.l.). d. The Sidama Highlands The Sidama Highlands are separated from the Bale Highlands by the Genale river valley. The area constitutes the southwest extension of the southeastern highlands. The plateau slopes away gently to the south and southeast, and is drained by the Genale river and its tributaries. 29  Grade 9| Geography B. The Southeastern Lowlands These lowlands extend from the foot hills of the southeastern highlands along the Ethio-Somalian and Ethio-Kenyan borders. Their general elevations lie between 500 and 1000 m a.s.l. They consist of: Þ the Ogaden plains, Þ the Borena plains, and Þ the Elkeri plains, Þ the Genale plains. These landforms are highly extensive lowlands. They are characterized by extreme climatic condition with low annual rainfall-often below 500 mm. Most of these lowlands are covered by sandstones and recent marine deposits. The people practice a pastoralist way of life because of the harsh climate. III. The Rift Valley What is the difference between a river valley system and a rift valley system? Can you give examples? The Ethiopian Rift Valley System is a narrow strip of land, which stretches from the Afar Depression in the north, through the Rift Valley Lakes’ region up to Lake Turkena and Chew Bhair. The Ethiopian Rift Valley System is part of the Great East African Rift Valley, which covers a distance of 5600 kms in Africa. The Great East African Rift System is a set of fractures in the earth’s crust that extend from the Jordan River valley in the north, through the Red Sea, and then across East and Central Africa to Mozambique in the south (Figure 1.6). 30  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE Figure 1.6.: The Rift Valley System of Ethiopia and the Horn The rift valley was, as indicated earlier, formed at the end of the Tertiary Period as a result of tectonic epeirogenic activity. The presence of active volcanoes, minor faulting, hot springs, cinder cones fumaroles and geysers could be good evidence for the unstable nature of the region geologically. As you can see in fig. 1.6, the Ethiopian Rift Valley System runs diagonally from northeast to southwest and divides Ethiopia Highlands into two. It covers a total length of 1700 kilometers in Ethiopia and Eritrea. 31  Grade 9| Geography Covering a length of 1700 kms, the Ethiopian Rift Valley System comprises 18 percent of the country’s total area. It is subdivided into three main parts: a) The Afar Triangle (northern), b) The Main Ethiopian Rift or the Lakes’ Region (central), and c) The Chew-Bahir Rift (southern). a) The Afar Triangle (Northern Part) The Afar Triangle is the largest and widest part of the system extending 200-300 kilometers. Its altitude is generally low, ranging from 116 meters below mean sea level at the Kobar Sink to about 900 meters above sea level at Awash. Much of the area here lies below sea level. This part of the Ethiopian Rift System is characterized by Þ Faulted depressions (the Dallol Depression) and grabens (also called troughs), and Þ Cinder cones and Volcanic mountains Also, a large part of the area is covered by extensive salt plains and lakes (for instances, Lake Assale and Lake Afrera). The Afar triangle is bounded by parallel fault lines on the east and west. Its floor is made up of: Þ Grabens such as the Tendaho Graben, Þ Volcanic ash and lava deposits, Þ Lacustrian and fluvial deposits, and Þ Volcanic mountains such as Mount Fentalle. What is more, the Afar Triangle has special characteristics that do not exist in other regions of Ethiopia. It consists of: Þ Fossil rich sediments, and Þ Rich archeological sites have shown us that the area was the home of the ancient ancestors of primates and hominids. b) The Main Ethiopian Rift or the Lakes Region (Central Part) The central subdivision of the Ethiopian Rift system, i.e., the Main Ethiopian Rift, covers the area from the lower Awash basin up to Lake Chamo. This subdivision is the most elevated and narrowest part of the Ethiopian Rift Valley. It is also the wettest, most densely vegetated, and most densely populated. 32  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA UNIT ONE Unlike others, sedentary farming is practiced here. The area also includes numerous lakes of enormous economic and aesthetic value. c) The Chew-Bahir Rift (Southern Part) The southern subdivision of the Ethiopian Rift system, the Chew-Bahir Rift, is also known as the Omo-Gibe trough. It is the smallest section of the Ethiopian Rift System separated from the Lakes’ Region to the north by the Konso Highlands and its surroundings. It consists of an extensive shallow marshy area covered by tall grasses into which the Sagan and Woito streams end. In the vicinity of Arba Minch, this part of the Ethiopian Rift valley system is split into the Ganjuli and the Galena Valleys by the Amaro mountain range. At large, the Chew-Bahir Rift region is occupied by a pastoralist population. Activity 1.5. Answer the following questions 1. Draw a map of Ethiopia showing the major physiographic divisions. 2. Why is the Baro-Akobo lowland the wettest of all lowlands? 3. Draw a map of the Rift Valley System in Ethiopia and demarcate its subdivisions. 33  Grade 9 | Geography UNIT SUMMARY 🌍 Ethiopia is located in Eastern Africa within the 3oN-15oN latitudes and 33oE- 48oE longitudes. Regarding shape, Ethiopia has more or less compact shape. 🌍 In terms of size, Ethiopia is the tenth largest country in Africa. It has an area of 1,106,000 square kilometers. Because of its large size, Ethiopia enjoys a diverse climate, a great variety of fauna and flora, diversified ethnic groups and a large potential of arable land as well. 🌍 The geological time scale measures time on a scale involving four major geological eras. The geological structure of Ethiopia is the result of the geological events that occurred during these eras. For example, crystalline basement complex rocks were formed during the Precambrian era; peneplanation took place during the Paleozoic era; land mass sinking and up-lifting were dominant during the Mesozoic era; formation of Ethiopian Rift Valley System during Cenozoic era respectively. 🌍 The landforms of Ethiopia are largely the results of the Cenozoic era tectonic and volcanic activities. Consequently, Ethiopia has rugged mountains, plateaus, ambas, river gorges, a rift valley and lowlands. The altitudinal variation in Ethiopia ranges from the highest peak, Ras Dashen (4620 meters above sea level) to the lowest point, Kobar Sink (116 meters below mean sea level). UNIT ONE 34  GEOLOGICAL HISTORY AND TOPOGRAPHY OF ETHIOPIA REVIEW EXERCISE PART I: MULTIPLE CHOICE ITEMS Direction: Choose the correct word or phrase from the given alternatives. 1. Which one is true about geomorphology? A. Deals with the distribution of plants and animals B. Examines the pattern of climate C. Studies landforms and their distribution D. Studies human influence on the atmosphere 2. Which neighboring country shares the longest boundary line with Ethiopia? A. Somalia C. Sudan B. Eritrea D. Djibouti 3. We cannot observe the outcropping basement complex rocks in one of the following areas of Ethiopia: A. In Central Tigray C. In the Abbay gorge B. Around Assossa D. In Central Shewa 4. As Hintalo sandstone is to Jurassic, Upper sandstone is to A. Permian C. Cretaceous B. Cambrian D. Triassic 5. The Afar Horst that extends into Djibouti was formed during A. Quaternary period C. Triassic period B. Tertiary Period D. Jurassic period 6. One can associate the Mesozoic Era with the formation of A. Igneous rock C. Sedimentary rock B. Metamorphic rock D. A and B 7. All of the following are drained by the Abbay and its tributaries, except, A. The Southwestern Highlands B. The North and Western Highlands C. The Central Highlands D. The Southeastern Highlands Unit Summary and Review Exercises 35  Grade 9 | Geography 8. The north central Massif are separated from the plateau of Tigray by the A. Mereb River C. Tekezze River B. The Danakil Lowlands D. Abbay River 9. The smallest sub division of the western highlands is A. Shewan plateau C. North central massif B. Tigrean plateau D. Semein mountain PART II: COMPLETION ITEMS Directions: Complete each of the following sentences with the correct word or phrase. 10. During the Triassic period, land subsidence (sinking) began in the _______________ part of Ethiopia and progressed towards the ______________ part of the country. 11. The landforms of Ethiopia are largely the result of the ________________ era. 12. The _______________ era is the oldest and longest geological era. 13. The ________________ era is known for the predominance of invertebrates. PART III: SHORT ANSWER ITEMS Direction: Give a short Answer for the following questions. 14. Who was Eratosthenes? What did he contribute to geography? 15. Explain how wide is the scope of geography? 16. What are the major branches of geography? 17. What is the difference between a relative location and an absolute location? 18. What is the distinction between a vicinal location and a geological location? 19. What are the advantages of compact shape? 20. Describe the major geological events that occurred during the Cenozoic era of Tertiary Period in Ethiopia. 21. State why sandstone and limestone are seen as surface outcrops in the Plateau of Tigray. 22. Describe the geological era which was significant regarding the formation of the various landforms in Ethiopia. UNIT ONE 36  CLIMATE OF ETHIOPIA UNIT TWO UNIT TWO 2. CLIMATE OF ETHIOPIA INTRODUCTION Climate is an important control over thedistribution of flora and fauna and in consequence largely determines the agricultural activities, and the materials available for shelter and clothing. Unit Outcomes By the end of this unit, you will be able to: ✅ recognize the meaning and concepts of weather and climate; ✅ identify elements of climate; ✅ distinguish elements of climate from its controls; ✅ compare and contrast the spatial and temporal variations of climate; and ✅ identify factors affecting climate of Ethiopia. 37  Grade 9| Geography Main Contents 2.1 Meaning of Weather and Climate 2.2 Elements of Weather and Climate 2.3 Controls of Weather and Climate in Ethiopia 2.4 Climatic Regions and Seasonal Variations in Ethiopia 2.5 Measurements of Weather and Climate 🌐 Unit Summary 🌐 Review Exercise 2.1 MEANING OF WEATHER AND CLIMATE At the end of this section, you will be able to: ✅ recognize the meaning and concepts of weather and climate; ✅ define weather and climate; and ✅ describe the difference between weather and climate. 🔑 Climate 🔒 KEY TERMS 🔑 Weather What do you know about the concepts of weather and climate? Do you see any change in the weather day in and day out? The word “weather” and “climate” are closely related but have quite different meaning. Weather refers to the condition of the atmosphere in terms of temperature, rainfall, pressure, wind, moisture, cloud cover, humidity etc. observed in a certain place over a short period of time. It is a phenomenon which varies very much from hour to hour, even from day to day. While climate is a pattern of weather condition experienced in an area over a long period of time. It considers the trends, fluctuation and vibration that may occur in departure from the average conditions in time and space. A large area can experience only one type of climate. 38  CLIMATE OF ETHIOPIA UNIT TWO Activity 2.1 Answer the following question. 1. Write a minimum of three major differences between weather and climate. 2.2 ELEMENTS OF WEATHER AND CLIMATE At the end of this section, you will be able to: ✅ identify elements of weather and climate; ✅ define the elements of weather and climate; and ✅ differentiate the elements of weather and climate from their controls. 🔑 Air pressure 🔒 KEY TERMS 🔑 Precipitation 🔑 Cloud cover 🔑 Temperature 🔑 Humidity 🔑 Wind What are elements of weather and climate? What is the significance of knowing the climatic condition of a place? Both weather and climate are composed of the following elements. Þ Precipitation - is any liquid or frozen water that forms in the atmosphere and falls back to the Earth in form of rain, sleet, hail, and snow. Þ Temperature - is the degree of measurement of hotness or coldness of an object. Þ Humidity - is the concentration of water vapor present in the air Þ Air pressure - is the force exerted on a surface by the air above it as gravity pulls it to Earth. 39  Grade 9| Geography Þ Wind - Wind is the movement of air, caused by the uneven heating of the Earth by the sun and the Earth’s own rotation. Þ Sunshine- is a direct sunlight to which a given area is exposed. Þ Cloud- is any visible mass of water droplets or ice crystals suspended in the atmosphere. The distribution of these elements over the surface of the earth is uneven in terms of magnitude and time. This spatial and temporal distribution of climatic elements is governed by the climate control factors described in the sections below. Activity 2.2 Answer the following question. 1. List the most important elements of weather and climate in Ethiopia. 2.3 CONTROLS OF WEATHER AND CLIMATE IN ETHIOPIA At the end of this section, you will be able to: ✅ distinguish elements of climate from its controls. 🔑 Altitude 🔒 KEY TERMS 🔑 Mountain barriers 🔑 Distance from the sea 🔑 Ocean currents 🔑 Latitude There are varieties of climate in Ethiopia. The spatial and temporal distribution of the climatic elements in Ethiopia is determined by various physical factors which are generally known as controls of weather and climate. 40  CLIMATE OF ETHIOPIA UNIT TWO The most important are: a) Latitude b) Altitude c) Mountain Barriers d) Revolution of the earth and the inclination of the earth’s axis e) Distance from the sea f) Ocean Current a) Latitude Latitude, as a climate control, is the angular location of a place or point with reference to the direct rays of the sun. When we speak of the latitudinal impact on the climate of Ethiopia, we are considering angle of the sun ray in country. This is because the rays of the sun fall vertical on the equator and slanting in the temperate and polar regions (See Figure 2.1). Figure 2.1: Insolation Receipt and Earth's Curved Surfaces (Source: Pearson Education Inc., (2013)) 41  Grade 9| Geography Ethiopia’s location within the tropical zone results in; Þ high temperatures during most of the year, Þ high daily (diurnal) ranges of temperature, Þ relatively small annual ranges of temperature, and Þ little difference between summer and winter in the ratios of daylight to night. b) Altitude Do you have information about the altitude of the place where you are living? Is it a highland or lowland? Is the temperature mild or hot or cold? Altitude is the main factor that determines the spatial distribution of temperature in Ethiopia. Different places that exist on the same plane or angle of the rays of the sun might be expected to experience equal temperatures. However, due to the impact of altitude, they do not. For example, three Ethiopian cities, Bako, Addis Ababa, and Awash all lie on the 9oN latitude, and therefore they might be expected to receive equal magnitudes of direct rays from the sun and therefore equal temperatures. However, their altitudes vary, and therefore their temperatures vary, as shown in Table 2.1. Table 2.1. The Role of Altitude in Modifying Temperatures Towns Latitude Altitude Average annual temperature Addis Ababa 9 oN 2,200 m.a.m.s.l. 16oC Bako (West Shewa) 9 oN 1,800 m.a.m.s.l. 17oC Awash 9 oN 916 m.a.m.s.l. 25oC The table illustrates the effect of altitude on temperature, confirming the fact that temperature decreases as altitude ascends from the lowlands towards the interior highlands. c) Mountain Barriers Mountain barriers can affect climate in that they exert influence on the spatial distribution of rainfall. Places located on the leeward side of mountains (also called rain shadow) receive little rain. 42  CLIMATE OF ETHIOPIA UNIT TWO The side of the mountain facing the wind laden with moisture is called the windward side mountain. Leeward side is named the other side of the mountain that does not face the laden moisture. Figure 2.2.: Effects of Mountain Barriers d)Revolution of the Earth and the Inclination of the Earth’s Axis The axis of the earth inclines 23½o to the normal of the elliptic. As the earth revolves around the sun, this inclination produces a change in the angle of the sun’s rays, thereby affecting the length of time that the sun shines on the earth every other day (See Figure 2.2). Changes in the length of the day and angle (directness) of the sun’s rays cause seasons. These different seasons result in the temporal variation of temperature in a year in Ethiopia. Figure 2.3: Annual March of the Seasons (Source: https://www. studyandscore.com) 43  Grade 9| Geography e) Distance from the Sea Do you know that water bodies or lakes (at local levels) have a moderating effect on the climate of vicinal or adjacent land areas? Water bodies and landmasses have different levels of heat absorption. Land masses absorb and release heat energy more quickly than water bodies do. Distance from the sea affects the Horn’s climate only in coastal areas that are adjacent to the Red Sea and the northwestern Indian Ocean. Towards the interior, the role of distance from the sea in climate control is insignificant. f) Ocean Current Warm and cold ocean currents can affect the climate of coastal regions, but only when local winds blow in from the sea. Warm currents heat the air over the ocean and bring higher temperatures over land. Cold currents can lower air temperatures and can bring colder temperatures over land. In Ethiopia the role of ocean current in climate control is inconsequential. NOTE Among the above mentioned controls of climate, the climate of Ethiopia is dominantly controlled by altitude and latitude. Activity 2.3 Answer the following questions 1. Explain how Ethiopia’s latitudinal location affects the distribution of climate. 2. Why is altitude known as the strongest of all the controls of climate in Ethiopia? 3. Why every place in Ethiopia experiences the overhead sun twice in a year? 44  CLIMATE OF ETHIOPIA UNIT TWO 2.4 CLIMATIC REGIONS AND SEASONAL VARIATION IN ETHIOPIA At the end of this section, you will be able to: ✅ identify agro-climatic zones of Ethiopia; and ✅ compare and contrast the spatial and temporal variations of climate in Ethiopia. 🔑 Agro-climatic zones 🔒 KEY TERMS 🔑 Kolla 🔑 Alpine or Afro-Alpine 🔑 Subtropical 🔑 Bereha 🔑 Woina Dega 🔑 Dega 🔑 Wurch/Kur 🔑 Inter-Tropical Convergence Zone 2.4.1 Agro-climatic Zones of Ethiopia In Ethiopia, the impact made by altitude has resulted in the formation of five agro- climatic zones. These zones have traditionally been defined in terms of temperature (see Table 2.2). Table 2.2. Agro-climatic Zones Altitude in Traditional agro- Global Mean annual meters ecological name equivalence temperature in oC 3,300 and above Wurch/Kur Alpine or Afro-Alpine 30 45  Grade 9| Geography a)Wurch-Zone Areas Do you know that the term wurch has resemblance to temperature severity? The Wurch-zone areas have the highest altitudes and lowest temperatures. Frequently they have temperatures of less than 10oC. These areas exist in the very high mountains of South Gondar, Wollo, Shewa, Arsi and Bale. Example: Þ Mt. Ras Dashen in Semine Gondar Þ Mt. Guna in South Gondar Þ Mt. Megezez in North Shewa Þ Mt. Batu in Bale, etc. b) Dega-Zone Areas What crops are grown in Dega areas? The Dega-zone areas are highland areas with lower altitudes and higher temperatures than Wurch-zone areas. Historically, Dega-zone agro-climatic areas were the home of concentrated human settlement. They were chosen because of the features below: Þ Secure location (from which people could defend themselves from threats) Þ Reliable rainfall Þ Absence of tropical diseases such as malaria, etc. Due to this high concentration of human population, the Dega zone has been intensively cultivated and has a high rate of soil erosion, overgrazing and deforestation. Some of the humid areas of this zone support two growing periods per year under rain-fed agriculture. Example: Þ Dinsho in Bale Þ Hulla in Sidama Þ Chillallo in Arsi Þ Debresina in North Shewa C) Woina-Dega-Zone Areas What is your understanding why the term Woina Dega comes after Dega? Does the term mean milder Dega? The Woina-Dega-zone areas contain most of Ethiopia’s agricultural land. They are the country’s main areas producing: Þ Surplus grain Þ Inset and its derivatives 46  CLIMATE OF ETHIOPIA UNIT TWO In the Woina-Dega zone, as in the Dega zone, there can be two growing seasons when rainfall reliability is high. d) Kolla Zone Areas What are the dominant crops grown in Kolla areas? Kolla is a (warm-to-hot semi-arid climate). Kolla is the climate of the hot lowlands with an altitudinal range of 500 to 1500 m a.s.l. Average annual temperatures are between 20oC and 30oC. Although mean annual rainfall ranges between 410 mm and 820 mm, it can be as high as 1600 mm in the wet western lowlands of Gambella. Rainfall is highly variable from year to year. Example: Western lowlands. e) Bereha-Zone Areas Can we grow crops in Bereha zone areas? Bereha is the hot arid climate. Bereha is the climate of the desert lowlands that are found below 500 m above mean sea level where the average annual rainfall is less than 400 mm, and average annual temperature is over 30oC. Bereha is usually characterized by strong wind, high temperature, low relative humidity, and little cloud cover. Evapotranspiration is always in excess of rainfall in some places. Example: Danakil depression in Afar lowlands. Figure 2.4: Agroclimatic Zones of Ethiopia (Source: EMA ,1994) 47  Grade 9| Geography 2.4.2 Seasonal Variation in Ethiopia A season is a period of the year characterized by a particular set of weather conditions resulting from the inclination of the earth’s axis and the revolution of the earth around the sun. The same cycle of season is repeated year after year. 2.4.2.1 Seasonal Variation of Temperature in Ethiopia Can you identify the temperature differences in Ethiopia between the months of April/May and those of October/November? How do these differences occur? In Ethiopia, temperatures vary from season to season. For example, in most parts of Ethiopia, high temperatures are recorded from March to June. Conversely, low temperatures are recorded from November to February. These variations are primarily due to: Þ the tilting of the earth at 23½º to the normal elliptic, and Þ the distance of the overhead sun and its apparent north-south movement across the equator as the earth revolves around the sun. During the winter season of the northern hemisphere, Ethiopia experiences the “Bega” season. During this season, day have clear skies. Thus, the incoming solar rays are intense. As a result temperature increases in day time and abruptly decreases at night because of clear sky. This, therefore, results in high diurnal range of temperature. Þ The mean maximum temperatures are experienced over the western, north eastern and south eastern lowlands while the lowest temperatures are over the Semein and Arsi-Bale mountains. Þ The highest temperature i.e. over 45oC is recorded in the Danakil Depression - the hottest place of Ethiopia. 2.4.2.2 Seasonal Variation of Rainfall in Ethiopia Do you distinguish the two concepts spatial and temporal? Which of the two terms is very much explanatory in the distribution of rainfall in time series? Rainfall, like temperature is a major element of climate. Ethiopia experiences marked spatial and temporal variations of rainfall. 48  CLIMATE OF ETHIOPIA UNIT TWO A. Spatial Variation of Rainfall in Ethiopia The spatial variation is the result of strength and nature of prevailing weather systems following the oscillation of the Inter Tropical Convergence Zone (ITCZ). NOTE As described earlier, Ethiopia’s weather systems also result from the apparent movement of the overhead sun, prevailing winds and the presence of barrier that checks the moisture arrival into the area Inter-Tropical Convergence Zone (ITCZ) It is a low atmospheric pressure zone formed by the convergence of northeasterly and southeasterly trade winds. It shifts north and south of the equator following the position of the overhead sun. In June, its position is at the Tropic of Cancer. During this time, Ethiopia comesunder the influence of the Equatorial Westerlies and Easterlies. As they originate from water bodies, these winds bring moisture to the highlands, but decrease their magnitude and length of rainy periods northwards. In December, its position shifts to the Tropic of Capricorn leaving the region for the prevalence of the Northeast Trade winds that are non-moisture-laden as they originate from the continental landmass. During this time only lowland areas in Afar region close to the coast receive some amount of rain given that these winds pick up little moisture as they blow passing over the Red Sea. In most of Ethiopia, it becomes dry season. In March and September, the position of the ITCZ is around the equator. Hence,the Equatorial Easterlies provide rain to the Southeastern lowlands, Central and highlands of Ethiopia. B. Temporal Variation of Rainfall in Ethiopia Ethiopia’s rainfall is characterized by seasonal variation. There are two main rainy seasons: Kiremt (summer) that extends from June to August and Belg (spring) that covers the time from March to May. These two rainy seasons contribute more than 90% of the country’s rain supply. There are two other rainy seasons namely the 49  Grade 9| Geography Meher (autumn) rains and the Bega (winter) rains. Compared to the two main rainy seasons, the duration, volume, and aerial coverage of Meher (autumn) rains that takes place from September to November are less. The Bega (winter) is generally the dry season that takes place from December to February. It supplies small amount of rain only to the Afar lowlands. 2.4.3 Rainfall Regions of Ethiopia Based on rainfall distribution, both in space and time, five types of rainfall regions can be identified in Ethiopia. These are: a) Year-round rainfall region (wet in most months) b) Summer rainfall region c) Autumn-and-spring rainfall region d) Winter rainfall region e) Merged spring, summer, and autumn rainfall region Each region is discussed in turn as follows a. Year-round Rainfall Region (wet in most months) In Ethiopia, the area of year-round rainfall includes the southwestern plateau comprising the highlands of Wollega, Kafa, Illubabor and Gamo and Goffa. The reason for the high rainfall and an exceptionally long wet season is due to the dominance of the equatorial Westerlies wind system. They pick up moisture from the Atlantic Ocean. This region can be represented by the following stations, namemely; Gore, Mizan, Metu, Bonga, Gambella, etc. The region has more rainy days than any other part of the country. The average rainfall varies from 1400 mm to 2200 mm. The year-round rainfall region is represented by the letter B on Figure 2.5. b. Summer Rainfall Region The summer rainfall region is the largest in the country. This region consists of the Northwest Highlands and Western Lowlands, and can be represented by the following stations, namely; Debre Markos, Fitche, Gondar, Bahir Dar, etc. Its moisture-bearing winds are the Equatorial Westerlies and Easterlies. The summer rainfall region is represented by the letter A in Figure 2.5. 50  CLIMATE OF ETHIOPIA UNIT TWO c. Autumn-and-Spring Rainfall Region The autumn-and-spring rainfall region covers the southeastern highlands and associated southeastern lowlands. They can be represented by the following stations: Gode, Moyalle, Jigjiga, Yabello. The region’s moisture-bearing winds are the Equatorial Easterlies. They pick up moisture from the Indian Ocean, and they blow over the autumn and spring rainfall region when the Northeasterlies and Equatorial Westerlies are weak. The region’s average rainfall varies from less than 500 to 1000 mm. The autumn-and-spring rainfall region is represented by E in Figure 2.5. NOTE In Ethiopia, highland rainfall is more dependable than lowland rainfall. However, highland dependability decreases from the southwestern highlands in all directions. In short, rainfall variability (deviation from the expected amount and time) decreases from areas of heavy rains to areas of low rainfall. d. Winter Rainfall Region The winter rainfall region consists of the eastern escarpment of the western highlands, the middle Rift Valley section and the Afar subdivision. The winter rainfall region can be represented by the Assaita station (Afar Region). The region’s moisture-bearing winds are, for the most part, the North Easterlies. The air mass is continental (dry) and has only a short sea trajectory (that is the Red Sea). It is represented by letter D in Figure 2.5. The region’s total annual moisture is very low and of short duration. e. Merged Spring, Summer, and Autumn Rainfall Region The merged spring, summer and autumn rainfall region is the smallest in the country. It consists mainly of the western foothills of the Southeastern Highlands. The region’s total annual rainfall varies from 1500 mm to 1000 mm. It covers a corridor that stretches from the Sidama Highlands to the Hararge Plateau. The merged spring, summer, and autumn rainfall region is represented by the letter C in Figure 2.5. It can be represened by the following stations namely, Assaita, Awash, and etc. 51  Grade 9| Geography Figure 2.5: Rainfall Regions of Ethiopia Activity 2.4 Answer the following questions 1. What do we mean by spatial and temporal in the context of Geography? 2. Identify your own agro-climatic zone by referring to your area’s altitude. You might be able to obtain the meters above sea level value of your altitude from your area’s kebele offices or from those of other agencies in your area. Your teacher may help you as you try to get that information so that you can use it to identify your agro-climatic zone. 3. Identify all the characteristics of your agro-climatic zone. 4. State the dominant wind systems over Ethiopia during the “Bega” and “kiremt” seasons. 5. Identify your locality, based on its rainfall seasons. In which seasons do you experience rain? 6. What moisture-bearing winds prevail over your area? 7. What is the attractive factor for the moisture coming as rain to your locality? 52  CLIMATE OF ETHIOPIA UNIT TWO 2.5 MEASUREMENTS OF WEATHER AND CLIMATE At the end of this section, you will be able to: ✅ measure the temperature variation from the thermometer; ✅ read the amount of rainfall receipt from a rainguage; ✅ measure air pressure with a barometer; and ✅ detect wind direction with the help of a wind vane. 🔑 Anemometer 🔒 KEY TERMS 🔑 Thermometer 🔑 Barometer 🔑 Wind vane 🔑 Rain gauges A. Measuring and Recording Air Temperature Temperature is a very important element of climate and weather. The instrument for measuring temperature is the thermometer, which is a narrow glass tube filled with mercury or alcohol. It works on the principle that mercury expands when heated and contracts when cooled. On thermometers, temperatures are marked in one of two ways. In °F. (Fahrenheit) the freezing-point is 32°F. and the boiling-point is 212°F. For most scientific purposes the Centigrade °C. scale is preferred. Its freezing-point is 0°C. and its boiling-point is 100°C. These two scales are interconvertible. Look at the following formula: Focus Mean daily temperature: it is calculated by adding the maximum and minimum temperature of the day and dividing the sum by 2. Daily (diurnal) range of temperature: it is the difference between the daily maximum and daily minimum temperature. 53  Grade 9| Geography Mean monthly temperature: is determined by adding together the daily averages and the dividing the number of days in a month. Mean annual temperature: it is calculated by adding the mean monthly temperatures and dividing the sum by 12. Annual range of temperature: it is the difference between the temperatures of the hottest and coldest months. b. Measuring and Recording Rainfall Rainfall is measured using a rain gauge. The rain gauge is usually anchored in the ground with the top of the gauge around 30cm above the ground surface to ensure that rain splash does not affect the results. The depth of the rain in millimeters can be read from the side of the container at least once a day (usually at 9:00a.m). A records is kept of the amount of rain (if any) which has fallen during the past 24 hours. At the end of a month the daily amount rainfall records are added together and this gives, of course, the total amount of rainfall for that month. Focus Mean monthly rainfall:it is calculated by adding all the amounts of rainfall on daily basis for the month and dividing the sum by the number of days of the month. Total annual rainfall: it is calculated by adding the amounts rainfall of the 12 months. Mean annual rainfall: it is calculated by adding the annual amounts of rainfall for 30-35 years and dividing the sum by the number of those years. C. Measuring and Recording Air Pressure Air is made up of a number of mixed gases and has weight. It therefore exerts a pressure on the earth’s surface which varies from place to place and from time to time. This force that presses on the surface of any object can be fairly accurately measured. The instrument for measuring pressure is a barometer. The unit more commonly used for measuring pressure is called millibar and millimeter. At sea level, the mercury column is 1013.25 millibars, or 760 mm. 54  CLIMATE OF ETHIOPIA UNIT TWO d. Measuring and Recording Wind Speed Wind speed can be measured using an anemometer. The anemometer should be held at arm’s length, above the head so that the cups can rotate without any interference. e. Measuring and Recording Wind Direction Wind direction is reported by the direction it is blowing from, according to the compass. Wind blowing from the west is travelling eastwards so is called a westerly wind, not an easterly wind. Wind direction is often observed using a wind vane. Activity 2.5 1. Convert a) 70o F to oC b) 25oC to oF c) 15oC to oF Table 2.3: Average Temperature of Addis Ababa (1991-2020) Months J F M A M J J A A O N D Annual Min. 9 10 12 13 13 12 12 12 12 10 9 8 Temperature ( C) o Annual Max. 24 25 25 25 25 23 21 20 21 23 23 23 Temperature ( C) o Source: NASA Climate Data Service 2. By referring to Table 2.3; a) Calculate annual range of temperature. b) Calculate annual mean temperature. Table 2.4: Average Rainfall of Addis Ababa, 2020 Months J F M A M J J A A O N D Rainfall 13 30 60 80 85 140 280 290 150 25 7 7 (mm) Source: NASA Climate Data Service 3. By referring to Table 2.4; a) Calculate the total annual rainfall b) Identify the wettest and driest seasons. 55  Grade 9 | Geography UNIT SUMMARY 🌍 Climate is the average conditions of the atmosphere over a long period of time in a given area. Climatic elements include precipitation, temperature, humidity, air pressure, winds, etc. The spatial and temporal distribution of the climatic elements in Ethiopia is determined by various physical factors which are generally known as controls of climate. The most important are latitude, latitude, mountain barriers and evolution of the earth and the inclination of the earth’s axis. 🌍 The apparent spatial variation of altitude, in Ethiopia has resulted in agro- ecological zonation of climate ranging from ”Bereha” to “Wurch”. Especially in the highlands, Ethiopia experiences four seasons, namely ‘Kiremt’, Meher’, ‘Bega’ and ‘Belg’. Laterally, due to the altitude effect we see spatial variation of temperature, rainfall, vegetation and population density. 🌍 Based on the areal and seasonal variation of the spread of rainfall, Ethiopia is divided into five main rainfall regions, namely year-round rainfall region, summer rainfall region, autumn-and-spring rainfall region, winter rainfall region and merged spring, summer, and autumn rainfall region. UNIT TWO 56  CLIMATE OF ETHIOPIA REVIEW EXERCISES PART I: TRUE OR FALSE ITEMS Dection: Write "True" if the statement is correct and false if it is incorrect 1. Weather and climate both mean the same thing. 2. The majority of Ethiopia's agricultural land is located in the Dega agro- climatic zone. 3. A climate is a pattern of weather conditions experienced in an area over a long period of time. 4. The eastern escarpment of the western highlands, the middle Rift Valley section, and the Afar subdivision experience mostly summer rains. 5. The side of the mountain facing the wind laden with moisture is called the windward side. PART II: MULTIPLE CHOICE ITEMS Direction: Choose the correct word or phrase from the given alternatives. 6. Temperature variations in Ethiopia are mainly the result of A. altitude. C. ocean current. B. latitude. D. mountain barriers. 7. As summer rainfall is to the Northwest Highlands and Western Lowlands, _______________ is to the Southeastern Highlands and Southeastern lowlands. A. Winter Rainfall C. Year-round Rainfall B. Merged Spring, Summer, and D. Autumn and Spring Rainfall Autumn Rainfall 8. With regard to the traditional temperature zones of Ethiopia, which of the following matches the Tropical Climate? A. Bereha C. Wurch/Kur B. Qolla D. Woina Dega Unit Summary and Review Exercises 57  Grade 9 | Geography 9. Which of the following regions of Ethiopia receives year-round rainfall and is least likely to be affected by droughts? A. Eastern lowlands. C. Southwestern highlands. B. Western lowlands. D. North eastern highlands. 10. The short term state of the atmosphere, including, temperature, humidity, precipitation, wind, and visibility. A. Humidity C. Precipitation B. Climate D. Weather PART III: COMPLETION ITEMS Directions: Complete each of the following sentences with the correct word or phrase. 11. The year-round rainfall region corresponds to __________. 12. The two areas in Ethiopia with high rainfall variability are _____________ and __________________. 13. The two areas in Ethiopia with very low rainfall variability are ________ and ___________________. 14. ___________ is known as the strongest of all the controls of climate in Ethiopia. 15. ___________ is the instrument used to measure air pressure. PART III: SHORT ANSWER ITEMS Direction: Give a short Answer for the following questions. 16. What are the elements of weather and climate? 17. What are the factors controlling the distribution of climate in Ethiopia? 18. Which rainfall season, in Ethiopia, constitutes the highest contribution to livelihood of the farmers living on the highlands? 19. State the dominant wind systems over Ethiopia during the ‘Bega’ and ‘Kiremt’ seasons. 20. List the main instruments for measuring elements of weather and climate UNIT TWO 58  NATURAL RESOURCE BASE OF ETHIOPIA UNIT THREE UNIT THREE 3. NATURAL RESOURCE BASE OF ETHIOPIA INTRODUCTION As it is indicated in the unit title, now you are going to deal with the natural resource base of Ethiopia that is concerned on those major natural resources such as soils, water, natural vegetation, and wildlife that are foundation of any economic development, food security and other basic necessities for the Ethiopian population. Unit Outcomes After completing this unit, you will be able to: ✅ recognize the concept of natural resources; ✅ elaborate on the major drainage systems of Ethiopia; ✅ explain the distribution of the major water resources in Ethiopia; ?