Omuramba

The Oshana system or Cuvelai wetland is an extensive network of low gradient, shallow running in a north-south direction gutters and valleys, the so-called Oshanas in North Central Namibia. It extends across much of the eponymous region Oshana - from Cuvelai in the highlands of Bié in the north to the north bank of the Etosha Pan and Ruacana in the west to the east Ondangwa and is the dominant landform in North Central Namibia. The origin take the Oshanas some 100 km north of the Angolan border, from where they run off to the south, unite to Ekuma and finally result in the Etosha Pan. The water flow is limited to the rainy season in the summer. After massive rainfall in the Greater Region northern Namibia / southern Angola occur even larger floods, the so-called Efundja on. Because of the wide branch and to the low gradient of the Oshanas then large areas of North Central Namibia are under water.

The Cuvelai system is a particular wetland based on the Ramsar Convention.

The Oshanas and your summer flood are essential for the Ovamboland. The predominant in the region, sandy soils and the Kalahari sandstones are extremely low in nutrients and provide little water retention capacity. Only the flood waters makes for a replenishment of groundwater reserves and a dense growth of grass, which is used for grazing. In addition, can be found in the flooded ponds and channels the summer months a lot of fish that are caught by the residents and used fresh or dried as food. However, the ponds and swamps also provide ideal breeding grounds for mosquitoes, so that, among other malaria is prevalent.

Since a larger Efundja was the last time occurred in the 50s of the 20th century, and has since been a massive increase in population, many settlements and grazing areas were also extended to actually rarely flooded depressions and Oshanas. In the dry season undermine the sustainability of the country is increasingly being exceeded and the groundwater reserves are depleted faster. At higher tides or even a large Efundja as in 2008 and 2011, this causes great damage and loss of property and livestock.

The Oshanas form open, grassy, but otherwise free of vegetation sinks ( " pans " ) in the dry state. Only the margins and higher areas are covered with mopane ( mopane Colophospermum ) and Makalani ( Hyphaene petersiana ). During the rainy season, fill the channels and valleys and it comes to the so-called ' Efundja ' or flood. While Western Oshanas be filled by running rainfall in the Angolan highlands, the waters of the eastern Oshanas usually only comes from local rainfall. Covering an area of over 30,000 square kilometers, the Oshana system then forms temporarily the most important wetland in Namibia.

Even after the rainfall the Oshanas remain longer time than shallow lakes filled slowly evaporate as water impermeable soil layers prevent rapid water seepage. During the Efundja the Oshana region is home to 260 species of birds including 90 species specific to wetlands ( flamingos, pelicans, saddle storks, etc.) and the channels are full of fish that are caught by the locals with bare hands or simple traps.

The sufficient availability of water and the entry of nutrient-rich sediments allowed a profitable agriculture, but is operated exclusively as a subsistence economy. Industrial agriculture hardly takes place despite the suitability of the country. Are grown mostly melons, pumpkins, corn, millet and beans. In addition, there is livestock.

Given the right conditions, the Oshana region to a high population density and is therefore correspondingly strong urban sprawl. The still mentioned in reports from the last century extended dry forests have disappeared and have been felled to meet the high demand for wood fire.