Travels with Olga: African Safari -- The Okavango Delta Meets Ecological Challenges

The Okavango Delta, one of the largest inland deltas in the world, began forming 60 million years ago during a time of great tectonic activity that resulted in depressions and uplifts on the plateau. Then, 20,000 years ago the land in between the two fault lines sank and filled with water, which formed the inland delta.

The headwaters of the Okavango River originate in Angola and flow across the Caprivi Strip (Namibia) to northwest Botswana where an alluvial fan forms into what is today known as the Okavango Delta. The southern part of the delta empties into Lake Ngami while the northern part bifurcates on the Cuando River, a tributary to the Zambezi River that flows into the Indian Ocean.

The total size of the delta is almost 6,200 square miles, about the size of Texas. The length of the rivers from Angola to the furthest tip of the alluvial fan is 932 miles.

Sustaining the delta requires rain from Angola, which gets three times more rain than Botswana does. The rainy season lasts three to four months from December to March. Unfortunately, the rain is not as plentiful these days as it was in the past. Our safari group was traveling in the delta in late December, and we experienced only one day of rain in two weeks.

The delta sports several dry lands that are like islands formed around minor rivers. There are also permanent and seasonal swamps depending on the amount of rain.

The delta's natural beauty and ecological importance has earned it several romantic nicknames including the "Jewel of the Kalahari", "the Louvre of the desert", and "Africa’s Last Eden". This natural phenomenon was created by a unique combination of geographic, climatic, and biological conditions where the natural fauna and flora have adapted to an ever-changing ecosystem, according to Africa Geographic (AG), an organization that focuses on safari travel and conservation. AG points out several threats to the delta that are changing it.

Animals like zebras and wildebeest have migrated from the areas where the rivers have dried up. They prefer the more permanent swamps because there are water and grazing areas.

One of the major challenges of the delta is the free movement of the animals. Since beef cattle were threatened by wild animals, a fence was built in 1980 to separate the wildlife in the east and cattle in the southwest. Cattle are an important part of Botswana's economy. In 2022, beef was the country's fourth largest export ($96 million) after diamonds and gems ($7.2 billion), minerals ($322.4 million), and electrical machinery and equipment ($166.7 million).

Human encroachment has created another threat to the delta in the form of hoof and mouth disease in cattle. This infectious and viral disease can cause high fever followed by blisters inside the mouth as well as lameness.

Invasive plants like the Kariba weed (a.k.a. salvinia weed) and water lettuce are suffocating fish and shooing away crocodiles, according to Dr. C. Naidu Kurugundla who wrote a paper on the subject. Since 1972 the government has been trying to get rid of this free-floating fern that inhabits still and flowing fresh water bodies. It has tried herbicides, manual elimination, and now uses an Australian weevil that feeds on these plants, which has proved successful.

Water lettuce is a minor weed in Botswana because of its limited distribution. The weed reproduces primarily through a seed bank, said Dr. Kurugundla. To arrest further additions to the seed bank in infested areas, the weed had been physically removed from 1999 to 2003 before the flower formation.

The negative impacts of the Kariba weed and water lettuce, he said, include blocking streams and channels, choking back water bodies, affecting navigation and recreational activities such as fishing and tourism, eliminating indigenous vegetation, and causing an eye sore to the tourists who visit the wild life areas of the wetland systems.

Game driver/guide Gulley of Camp Santawani talked to us about the delta's geography and ecological challenges. He said that climate change is having a great effect on the delta. Rivers used to be much bigger and there was more rain; now the rivers are more often dry as the intense heat evaporates the water. Trees are also dying. They provide interesting sculptures, but unfortunately signal that something is wrong.

The Okavango Delta is a UNESCO World Heritage site that is managed by UNESCO. There are no dams on the waterways although at one time Namibia wanted dams for hydroelectric power. The other countries in the Delta all agreed not to build any dams lest the ecological balance of the region be upset.

The delta is very important economically to the region. It supports tourism, which is Botswana's second largest revenue-producing industry. Tourism, in turn, provides employment. It is a source of water for plants, animals, and people as well as a source of food--plants and fish. Certain plants are used for basket weaving, which is another source of income for women who make the baskets.