Final Assessment

     The Okavango Delta is one of earth's most unique and exciting places. The area features plant and animal life that for most of the world can only be found in books and zoos. Out of the Angola Highlands flows the Okavango River which spills out into the Kalahari sands creating the vast waterways of the delta. This inland delta is made possible by a few unique geological features. The delta is a low lying plane between two fault areas on its southern and northern edge. This is what causes the delta to both fan out and to stay within its southern boundary, never reaching the sea. These faults are caused by the Great African Rift Valley found northeast of Botswana in Ethiopia. This rift valley and its plate tectonics may hold the secrets of the future for the Okavango.

10,000 Years in the Future:
     Speculations for the future of the Okavango Delta must include the impact of humans on the delta area. This impact was studied in 2010 by a non-profit group Elephants Without Borders (EWB). EWB conducted and aerial study of the delta that produced some shocking results. The numbers of large mammal species were decreasing rapidly. 11 of the large mammal species had declined in the delta by, on average, 61%. Some species like the wildebeest had declined by around 90%. These startling numbers along with the conflicts faced upstream over the usage of the water that will eventually make up the delta lead to one dismal hypothesis. The now lush fertile lowlands could become a desolate desert much like the Kalahari below. The difference however between this area and the Kalahari is the seismic activity in the delta.

Here you can see the path the rift valley will take as it tears Africa apart.

1,000,000 Years in the Future
     The African Rift Valley to the northeast in Ethiopia holds all of the secrets to the Okavango's future. The African Rift Valley is an area where the African and Somali plates are tearing apart creating a massive tear, or rift. Due to recent seismographic findings in the Okavango we can assume that the rift valley takes a westerly angle and cuts right through the delta. This means that as the rift continues to separate, the faults that create the Okavango will also continue to separate and create a large valley out of the current delta. We can hypothesize from this that in the future the delta will look much like the rift valley of today and the current rift valley will be a massive bay area as the Indian Ocean begins to flood into Africa. The current rift valley is characterized by jagged hills and large volcanoes, this is the future of the Okavango as well.

This map shows the frequencies of earthquakes in the Okavango. It is estimated they receive one significant quake a day.

This image shows the large jagged peaks on the edge of the large open valley that characterize the East African Rift Valley. This will eventually be flooded to form the boundary between the two new continents.

100,000,000 Years in the Future
     By this time in the future the Okavango Delta will be but a distant memory. In its place will lie a vast sea. This sea will separate Africa from a new continent that will split from the mainland of Africa. The Rift Valley will have torn the continent apart directly across the former Okavango Delta. Home once to the great mammals of land it will now house the great animals of the sea.

Sources: http://www.nytimes.com/books/first/e/eldredge-life.html

Fluvial Landscapes

The Delta begins in the panhandle where the Angola River dumps water and sediment into the wetlands. This sediment has become of particular concern in recent years as more and more discussion of building dams has arisen. The need for water in this geographic region cannot be understated. The Okavango sits atop the arid Kalahari Desert.

This image shows the massive Kalahari Desert directly below the Okavango Delta.

Due to this need for water in the surrounding areas many groups would like to dam the Angola River in an effort to keep that water from ever reaching the Okavango. The Institute of Environmental Engineering recently monitored the flow of water and sediment in an attempt to understand how damming the river could effect the delta. They found that the channels flow through a thick papyrus belt which helps to filter out the sediment. Flow velocities are decreased and aggradation of the channels are caused. Most of the sediment is a fine sand and is deposited onto the bottoms of the channels in a ripple like pattern.

This image displays the pattern in which the sand forms on channel bottoms.

This causes the channel bottoms to rise above the surrounding land. The water is held in the channel by vegetation until there is a gap. When the vegetation gives way a new channel will form and more sediment will be deposited. This is what creates the alluvial fan shape of the Delta. Should the Delta be dammed upstream this shape could be in jeopardy. If when dammed up, sediment is lost the Delta could become one large channel or an end-lagoon system. The sediment carried by the waters is really what creates this vast wetland and without it the Delta could be lost. 

Work Cited: http://www.northsouth.ethz.ch/news/past_events/past_events_zil/annualconference06/posterexhibition/Milzow.pdf

Hydrology

The hydrology of the Okavango Delta is of upmost importance due to the economic and ecological significance of area. We will attempt to overview the key hydrological aspects of the delta and how they in turn affect both native and global communities.

Tourists in the Okavango Delta

The delta is an alluvial fan covering nearly 12000 km squared. The climate in Botswana is semi-arid receiving only about 450 mm of rain per year. Due to the alluvial fan dispersing the water across the desert surface, and the dry climate nearly 95% of the water is lost into the atmosphere via evaporation. 

The delta only floods seasonally and varies greatly from year to year. The flood peaks in April at the northern point. The waters then disperse over the next 3-4 months traveling about 250km. During this 3-4 months the water floods into the entire alluvial fan by overland flow and various channels that connect the delta to its northernmost source. There are a few indicators of how much flooding will occur for any particular year. The best indicator is a high discharge at Maun, the source of the Okavango. This indicator can have major impacts on the economy of Botswana. It helps predict the number of tourists the region will be able to accommodate and how wide the flooding will take place. It can also have tremendous environmental repercussions as scientists and conservationists can determine the needs of the animal and plant populations in the region in order to preserve the delta and its biodiversity. This biodiversity can be attributed to the hydrological factors that have contributed so greatly to the formation of the delta every year. Many flora and fauna are unique to the Okavango region as well as the delta serving as a major junction for animal migration highways.

Animal life of the Delta

Sources:

Regional review: the hydrology of the Okavango Delta, Botswana—processes, data and modelling

Formation and Tectonics of the Okavango Delta.
     The Okavango Delta is one of the most peculiar places on earth. The delta is 18,000 square kilometers of waterways, reed beds and oasis forests in the middle of the desert. The Okavango, instead of emptying into the ocean as most deltas do, empties itself into the largest continuous stretch of sand in the world, the Kalahari Desert. This unique clashing of seemingly opposite worlds creates one of the most beautiful locations on earth as well as a thriving epicenter for African wildlife. But the secret to this mysterious desert oasis is not found on the surface but much deeper in the faults and pulling apart of tectonic plates which effect the surface here in mighty ways. It may shock you too learn that the Delta has, on average, one significant earth quake per day. Although never felt at the surface this activity alludes to the great forces that created this natural wonder.

     The waters that will eventually become the Delta originate in the Angola Highlands in the Cubango River. As it flows southeast into Namibia it becomes the Kavango River. 1000 miles later as it enters Botswana it becomes the Okavango River. A series of fault lines then cause the river to split into its fan-like form. The first is the Gomare fault. At this point the Okavango river splits into many different waterways. It then flows over many other parallel faults until it is finally stopped by the Kunyere and Thamalakane faults. These faults act to block the water from progressing into the desert and so the water, as if by magic, comes to an abrupt halt. 

     This faulting can be seen as a continuance of the African Rift Valley found to the northeast. Here the Nubian and Somali plates are pulling Africa apart. The faulting that has formed the Okavango owes its origin to this rift system that is so far away.

Sources:
http://www.nytimes.com/books/first/e/eldredge-life.html

http://www.eyesonafrica.net/african-safari-botswana/okavango-info.htm

http://education.nationalgeographic.com/education/encyclopedia/rift-valley/?ar_a=1

Introduction

This blog is a survey highlighting the geographic intrigues of the Okavango Delta located in Botswana.

  Created by Tyler Gautier for Physical Geography 1202. The Okavango Delta is a place often highlighted by nature programs on the National Geographic Channel. Thus many rainy days of my childhood were spent gasping at the size and strength of Africa's most dangerous beasts alongside the flocks and herds of the more fragile animals as they all clashed amidst the life bringing waters of the Okavango.

 Due to this childhood intrigue the Okavango Delta has long been a dream destination for future adventures. I look forward to learning and sharing more about this wild oasis of the African plains.