Terrain, Vegetation, and Drainage
Physio-graphically, Somalia is a land of limited contrast. In the north, a maritime semidesert plain parallels the Gulf of Aden coast, varying in width from roughly twelve kilometers in the west to as little as two kilometers in the east. Scrub-covered and generally drab, this plain, known as the Guban (scrub land), is crossed by broad, shallow watercourses that are beds of dry sand except in the rainy seasons. When the rains arrive, the vegetation, which is a combination of low bushes and grass clumps, is quickly renewed, and for a time the guban provides some grazing for nomad livestock. This coastal strip is part of the Ethiopian xeric grasslands and shrublands ecoregion.
Inland from the gulf coast, the plain rises to the precipitous northward-facing cliffs of the dissected highlands. These form the rugged Karkaar mountain ranges that extend from the northwestern border with Ethiopia eastward to the tip of the Horn of Africa, where they end in sheer cliffs at Caseyr. The general elevation along the crest of these mountains averages about 1,800 meters above sea level south of the port town of Berbera, and eastward from that area it continues at 1,800 to 2,100 meters almost to Caseyr. The country's highest point, Shimber Berris, which rises to 2,407 meters, is located near the town of Erigavo.
Southward the mountains descend, often in scarped ledges, to an elevated plateau devoid of perennial rivers. This region of broken mountain terrain, shallow plateau valleys, and usually dry watercourses is known to the Somalis as the Ogo.
In the Ogo's especially arid eastern part, the plateau—broken by several isolated mountain ranges—gradually slopes toward the Indian Ocean and in central Somalia constitutes the Mudug Plain. A major feature of this eastern section is the long and broad Nugaal Valley, with its extensive network of intermittent seasonal watercourses. The Nugaal river enters the Indian Ocean at Eyl. The eastern area's population consists mainly of pastoral nomads eking a living in a zone of low and erratic rainfall.
The western part of the Ogo plateau region is crossed by numerous shallow valleys and dry watercourses. Annual rainfall is greater than in the east, and there are flat areas of arable land that provide a home for dryland cultivators. Most important, the western area has permanent wells to which the predominantly nomadic population returns during the dry seasons. The western plateau slopes gently southward and merges imperceptibly into an area known as the Haud, a broad, undulating terrain that constitutes some of the best grazing lands for Somali nomads, despite the lack of appreciable rainfall more than half the year. Enhancing the value of the Haud are the natural depressions that during periods of rain become temporary lakes and ponds.
The Haud zone continues for more than sixty kilometers into Ethiopia, and the vast Somali Plateau, which lies between the northern Somali mountains and the highlands of southeast Ethiopia, extends south and eastward through Ethiopia into central and southwest Somalia. The portion of the Haud lying within Ethiopia was the subject of an agreement made during the colonial era. In 1948, under pressure from their World War II allies and to the dismay of the Somalis, the British "returned" the Haud (an important Somali grazing area that was presumably 'protected' by British treaties with the Somalis in 1884 and 1886) and the Ogaden to Ethiopia, based on an 1897 treaty in which the British ceded Somali territory to the Ethiopian Emperor Menelik in exchange for his help against plundering by Somali clans. Britain included the proviso that the Somali nomads would retain their autonomy, but Ethiopia immediately claimed sovereignty over them. This prompted an unsuccessful bid by Britain in 1956 to buy back the Somali lands it had turned over. The stretch of land has since been a considerable source of regional strife.
Southwestern Somalia is dominated by the country's only two permanent rivers, the Jubba and the Shabeelle. With their sources in the Ethiopian highlands, these rivers flow in a generally southerly direction, cutting wide valleys in the Somali Plateau as it descends toward the sea; the plateau's elevation falls off rapidly in this area. The adjacent coastal zone, which includes the lower reaches of the rivers and extends from the Mudug Plain to the Kenyan border, averages 180 meters above sea level.
The Jubba River enters the Indian Ocean at Kismaayo. Although the Shabeelle River at one time apparently also reached the sea near Merca, its course is thought to have changed in prehistoric times. The Shabeelle now turns southwestward near Balcad (about thirty kilometers north of Mogadishu) and parallels the coast for more than eighty-five kilometers. The river is perennial only to a point southwest of Mogadishu; thereafter it consists of swampy areas and dry reaches and is finally lost in the sand east of Jilib, not far from the Jubba River. During the flood seasons, the Shabeelle River may fill its bed to a point near Jilib and occasionally may even break through to the Jubba River farther south. Favorable rainfall and soil conditions make the entire riverine region a fertile agricultural area and the center of the country's largest sedentary population.
In most of northern, northeastern, and north-central Somalia, where rainfall is low, the vegetation consists of scattered low trees, including various acacias, and widely scattered patches of grass. This vegetation gives way to a combination of low bushes and grass clumps in the highly arid areas of the northeast and along the Gulf of Aden.
As elevations and rainfall increase in the maritime ranges of the north, the vegetation becomes denser. Aloes are common, and on the higher plateau areas of the Ogo are woodlands. At a few places above 1,500 meters, the remnants of juniper forests (protected by the state) and areas of Euphorbia candelabrum (a chandelier-type spiny plant) occur. In the more arid highlands of the northeast, Boswellia and Commiphora trees are sources, respectively, of the frankincense and myrrh for which Somalia has been known since ancient times.
A broad plateau encompassing the northern city of Hargeysa, which receives comparatively heavy rainfall, is covered naturally by woodland (much of which has been degraded by overgrazing) and in places by extensive grasslands. Parts of this area have been under cultivation since the 1930s, producing sorghum and maize; in the 1990s it constituted the only significant region of sedentary cultivation outside southwestern Somalia.
The Haud south of Hargeysa is covered mostly by a semiarid woodland of scattered trees, mainly acacias, underlain by grasses that include species especially favored by livestock as forage. There vegetation forms spatially periodic patterns reminiscent of a tiger skin when viewed from above and therefore knowns as "Tiger bush". As the Haud merges into the Mudug Plain in central Somalia, the aridity increases and the vegetation takes on a subdesert character. Farther southward the terrain gradually changes to semiarid woodlands and grasslands as the annual precipitation increases.
The region encompassing the Shabeelle and Jubba rivers is relatively well watered and constitutes the country's most arable zone. The lowland between the rivers supports rich pasturage. It features arid to subarid savanna, open woodland, and thickets that include frequently abundant underlying grasses. There are areas of grassland, and in the far southwest, near the Kenyan border, some dry evergreen forests are found.
Along the Indian Ocean from Hobyo southwestward to near Mogadishu lies a stretch of dry coastal sand dunes, the Hobyo grasslands and shrublands ecoregion. This area is covered with scattered scrub and grass clumps where rainfall is sufficient although unpredictable. Much of this coast is thinly populated but overgrazing, particularly south of Mogadishu, has resulted in the destruction of the protective vegetation cover and the gradual movement of the once-stationary dunes inland. The original flora of this coast contains a number of endemic species and beginning in the early 1970s, efforts were made to stabilize these dunes by replanting. Endemic mammals are the Silver Dik-dik (Madoqua piacentinii), one of the world's smallest antelopes, and the Somali golden mole (Calcochloris tytonis). Other endemic species include two reptiles, a skink Haackgreerius miopus and a lizard Latastia cherchii and two birds, Ash's Lark (Mirafra ashi) and the Obbia Lark (Spizocorys obbiensis). The long-term political strife in Somalia has meant the coast is poorly studied and the state of the habitat unknown.
Other vegetation includes plants and grasses found in the swamps into which the Shabeelle River empties most of the year and in other large swamps in the course of the lower Jubba River. Swamps of East African mangroves are found at points along the coast, particularly from Kismaayo to near the Kenyan border. Uncontrolled exploitation appears to have caused some damage to forests in that area. Other mangroves are located near Mogadishu and at a number of places along the northeastern and northern coasts.
Read more about this topic: Geography Of Somalia