The Okavango Delta is a large, remote, and ecologically significant wetland located in northwestern Botswana. The Okavango Delta receives a strong annual flood pulse. But what is a flood pulse? The flood pulse is the annual rise and fall of the water levels in a river channel or river channels.
This is important for our river systems because it allows the floodplains to collect and channel water through and bring nutrients into the ecosystem. In this regard, the flood pulse helps maintain genetic and species diversity in the floodplain ecosystem such as the Okavango delta. Flood pulse brings in oxygen to help fauna and decomposition. The flood pulse also increases yields by increasing the surface area of water and showers the land with river biota.
The Okavango River Delta is one such river channel (s) in Botswana experiencing flood pulses making it the largest and most beautiful oasis in Africa, The Okavango Delta is thus this paradise with some of the richest wildlife in the world. But what causes the annual Okavango Delta flood and when does it happen? The water supply of the Okavango Delta comes from two sources, namely:
i) Most of the water in the Okavango Delta comes from the Cubango and Cuito rivers in Angola. That is, the source of the Okavango Delta lies in the Planalto highlands in Angola, 1,100 km away from Botswana. Several small tributaries form the Cuito River which flows south to Namibia and joins the Cubango River where it gains considerable momentum and breadth to become the Okavango River in Botswana.
ii) The source in the Angola highlands lies at 1200 metres above sea level and flows towards the Okavango which has an altitude of 1,000 metres above sea level at the top of the panhandle to 930m in the basin. This shows that the summer rain season in Angola leads to a dramatic swelling of the Cuito and Cubango Rivers which flows south, through Namibia until it finally reaches Botswana at Mohembo, where the river becomes known as the Okavango River. This water reaches the delta between March and June and peaks in July annually.
iii) the second significant amount of water in the Okavango Delta is from local rainfall in the Okavango area from November to February/March (about 450mm a year). Currently, there are rains in Botswana and in the Okavango Delta. These rains are adding a significant amount of water in the Okavango River Delta.
The Okavango River Delta consists of a multitude of main channels, smaller tributaries, and lagoons as well as floodplains, islands, and mainland areas. The watercourses are always changing due to annual flooding as well as a combination of sediment transport, seismic activity, the construction of termite mounds, the continual opening up of new channels by feeding hippopotami and the closing of others by new vegetation growth.
The Okavango Delta is the largest inland delta in the world. The Okavango Delta is thus a watery paradise in what is known for Kalahari sands transforming the desert natural environment into an ideal breeding ground for an incredible diversity of wildlife. The Okavango Delta is thus a rich wildlife ecosystem that supports international wildlife-based tourism industry.