The Great Rift Valley

Africa, the second largest continent on Earth, is connected to Asia through the isthmus of Suez.  Both the highest and lowest points are located in the eastern half:  Mt. Kibo, a peak in Tanzania at 19,340 feet is the highest, and the Qattarah Depression in Egypt, at 436 feet below sea level, is the lowest point.  The most spectacular feature of the continent, however, is the Great Rift Valley.

 The Great Rift Valley is a geologic depression extending about 3,000 miles from southwest Asia through eastern Africa, from the Jordan River valley to Mozambique. The valley, which is marked by a series of faults caused by volcanic action, is currently thought to be the product of plate tectonics.  At its lowest point it is ~1,300 feet below sea level at the Dead Sea and ~ 6,000 feet high in south Kenya.

In Asia, the historic region of Palestine, on the Levant shore of the eastern Mediterranean, is the northern anchor of the Rift Valley.  Al Biqa is an upland valley in Lebanon, between the Lebanon and anti-Lebanon mountain ranges, drained by two rivers: the Orontes, flowing north into Syria and the Litani flowing south through Lebanon where it empties into the Mediterranean Sea north of Tyre.  It is the northern end of the Rift Valley, which then continues through the valley of the Jordan River.  The headwaters of the Jordan River converge in northern Israel and flow south between Israel and the Golan Heights and through the Sea of Galilee (Lake Tiberias) into a below-sea-level valley called the Ghor, where it forms the boundary between Israel and the West Bank on the west, and Jordan on the east, before emptying into the Dead Sea, a salt lake in the arid Jordan trough of the Rift Valley on the Israel-Jordan border.  It is 1,292 feet below sea level, the lowest point on earth.  

The Rift Valley continues to and through the Gulf of Aqaba, the northern arm of the Red Sea, which separates Egypt’s Sinai Peninsula from Jordan and Saudi Arabia, into the Red Sea, which separates northeast Africa from the Arabian Peninsula.  The Red Sea, as part of the Rift Valley, includes the area from the Gulf of Aqaba and the Straits of Tiran, at the northern end, to the Bab el Mandeb at Djibouti, at the southern end, where it meets the Gulf of Aden. 

The Rift Valley returns to land at Danakil, a desert region in northeast Ethiopia and northern Djibouti, adjacent to the Bab el Mandeb, and continues southwest into Ethiopia, from the direction of Djibouti, toward a string of lakes starting southeast of Addis Ababa and running southwest.  The series of lakes include an unnamed lake followed by Lakes Ziway, Langano, Abiyata and Shala.  Then there is a small lake near Awasi, with Lakes Abaya and Ch’amo following, ending at the Ethiopia / Kenya border, with Lake Ch’ew Bahir.  The Rift Valley continues in northeast Kenya with Lake Turkana and then separates into the East Rift and the West Rift.

The East Rift Valley moves from Lake Turkana toward Lake Tanganyika east of Lake Victoria and west of Nairobi through the Olduvai Gorge in Tanzania, a ravine ~295 feet deep, forming the eastern edge of the Great Rift Valley.  The gorge is at the southern edge of the Serengeti National Park, southeast of Lake Victoria, north of Lake Eyasi, and southwest of Lake Natron.  The East Rift then continues to Lake Malawi (Nyasa) through a number of secondary lakes in Tanzania. 

 The West Rift Valley continues from Lake Turkana, west of Lake Victoria to Lakes Albert and Edward on the Uganda / Zaire border, south to Lake Kivu on the Zaire/Rwanda border.   Lake Kivu has the distinction of being Africa’s highest lake at 4,790 feet.  From Lake Kivu the rift goes through Lake Tanganyika to Lake Malawi (Nyasa).  Lake Tanganyika is a large freshwater lake, considered the second deepest lake in the world, having a maximum depth of


~ 4,700 feet.  Lake Malawi is also a large freshwater lake, but bounded by steep mountains.  It is drained by the Shire River into the Zambezi River and empties into the Indian Ocean through Mozambique.~ 4,700 feet.  Lake Malawi is also a large freshwater lake, but bounded by steep mountains.  It is drained by the Shire River into the Zambezi River and empties into the Indian Ocean through Mozambique.  At Lake Malawi, the eastern and western arms of the Great Rift Valley join and end in Mozambique, the southern anchor.

                         THE PROBLEM                 

                                                                                                                            
During the last 10-15 years, and possibly longer, studies of the Rift Valley in the Kenya / Tanzania regions have determined that an increasing flow of water, probably from an aquifer, deep well, underground river or other such water source, has been infiltrating parts of the Rift Valley in Africa.  While the local and short-term irrigation benefits of such flows are obvious, there is some concern of the long-term effects.  

 If the valley is traced on a map of eastern Africa, it will be seen from a physical map that the part of the rift from Djibouti to the lake region below Addis Ababa flows through a mountainous “funnel,” then enters the east and west arms of the rift, and thence through Lakes Tanganyika and Malawi and the Shire and Zambezi rivers to the Indian Ocean, forms an arc encompassing a land mass including all of Tanzania, Rwanda, Somalia and Burundi, major areas of Uganda and Kenya, and lesser areas of Mozambique and Malawi.  

Other considerations:  The rift is replete with faults and the area within the arc has suffered environmental stress due to deforestation and human-induced desertification.

POTENTIAL RISKS

The infiltration of water, while not an immediate problem, could in geological time cause major problems to the land mass within the arc:

• By the formation of a number of additional lakes which will in time (geological time) join to form an inland sea;

• By lubricating the faults, permitting them to temporarily relieve built-up stresses, but in the long-term cause more severe earthquakes when they do occur; 

• By adding substantial weight to the fault areas and causing the land mass included in the arc to partially or completely breakaway from the African continent.  This may occur in any one or more of three areas:

          Area 1.  Djibouti through the “funnel” to Lake Turkana, to the rift east arm, to the Olduvai         Gorge, to a point on the coast of Tanzania near Dar es Salaam, including the horn of Africa, all of Somalia, and major parts of Djibouti, Ethiopia, Kenya and Tanzania;

         Area 2.   Lake Turkana to the rift east arm, to the Olduvai Gorge, to a point on the coast  of         Tanzania near Dar es Salaam, south to the mouth of the Zambezi River, to Lakes Malawi    Malawi and Tanganyika, to the rift west arm, to Lake Turkana, including all of Uganda, Rwanda and Burundi, and major parts of Kenya, Tanzania, and Mozambique; or

              
          Area 3    All of Areas 1 and 2 from Djibouti to the mouth of the Zambezi River.

POSSIBLE SOLUTIONS

Despite the obvious dangers and the current risks, no solutions have been or are proposed.  In fact, few scientists or politicians are willing to acknowledge that problems exist and are willing to let nature take its destructive course, evidenced by the recent prolonged killer floods.

           2001
           LFC