Omaruru (river)

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Omaruru
ǂEseb
River bed of the Omaruru, on the right the trickle of a spring

River bed of the Omaruru, on the right the trickle of a spring

Data
location Namibia
River system Omaruru
source on Mount Etjo
muzzle at Henties Bay in the Atlantic Coordinates: 22 ° 5 ′ 40 ″  S , 14 ° 15 ′ 25 ″  E 22 ° 5 ′ 40 ″  S , 14 ° 15 ′ 25 ″  E

length 330 km
Catchment area 11,579.603 km²
Omaruru Rivier (2018)

The Omaruru ( khoekhoegowab ǂEseb ) is one of 12 ephemeral dry rivers ( Rivier ) in western Namibia and part of the Namib water region . It extends over 330 km from Mount Etjo in the east via the villages of Omaruru and Okombahe to Henties Bay on the Atlantic. The name Omaruru is derived from Otjiherero omaere omaruro for 'bitter milk' and refers to a bush ( stink bush ) that can be found in the Omaruru river bed and which makes the milk of grazing cattle bitter when consumed .

Hydrology

The catchment area of the Omaruru lies in the Erongo region and extends from the foot of Mount Etjo in an approximately 50 kilometers wide corridor to Henties Bay over 11,579.603 km². In the south, the catchment area includes parts of the northern Erongo massif and the Spitzkoppen complex. The highest point of the catchment area is around 2000 meters in the Erongo massif. The precipitation falls only sporadically and varies from 0 mm / a to 375 mm / a on Mount Etjo, about 20 percent of the catchment area receives an annual precipitation over 300 millimeters, 80 percent is below 100 mm / a. In Okombahe groundwater escapes and thus forms the basis for agriculture and grazing. The relatively high rainfall in the upper catchment area ensures that the Omaruru “deviates” most frequently from all dry rivers in Namibia (“Agreement” is a German-Namibian expression for the water flow of a river).

Due to the more intensive agricultural use in the area of ​​the Etjo mountain, silt is increasingly transported when the river enters , which seals the river bed in the lower reaches and thus reduces the formation of new groundwater . To hold back the clay loads, the Omdel Dam was built a few years ago 40 kilometers above Henties Bay , which is intended to increase the formation of new groundwater in the lower reaches.

Vegetation and fauna

The majority of the catchment area (62%) falls in the semi-desert area or the savanna transition zone, 31% are in the thorn bush savanna and around 6% are in the central Namib . In the central reaches of Okombahe, the upstream or near-surface groundwater forms the basis for extensive gallery forests with ana tree ( Faidherbia albida ), tamarisk ( Tamarix ), camel thorn ( Acacia erioloba ), salvadora , leadwood ( Combretum imberbe ), euclea and fig species . In addition, invasive species such as thorn apple ( Datura spec. ), Tobacco ( Nicotiana ) and fenugreek occur, which are increasingly spreading but are not eaten by cattle and game. The dense vegetation is the basis for a relatively intensive pasture management. Apart from the game and guest farms, there is hardly any game population in the wild.

Use and settlement

The population in the catchment area is relatively small at 13,000, settlement centers are Omaruru and Okombahe . 46% of the catchment area is owned by 102 private farms, 52% is communal land, and 2% is in the West Coast Recreational Area . The relatively high rainfall in the upper catchment area and the near-surface groundwater in the middle reaches near Okombahe offer the possibility of intensive agriculture and grazing. Around 38 kilometers east of Henties Bay, the river is dammed by the Omaruru Delta Dam to supply water to the coastal towns. Commercial farms also grow wheat, corn, and other crops. In the lower reaches, the Rössing mine is one of the largest consumers of water. The abstraction of groundwater from the Omaruru aquifer is greater than that of Swakopmund . Increasing tourism and population growth are also contributing to increasing water consumption and endangering groundwater reservoirs.

annotation

  1. ↑ Note: This article contains characters from the alphabet of the Khoisan languages spoken in southern Africa . The display contains characters of the click letters ǀ , ǁ , ǂ and ǃ . For more information on the pronunciation of long or nasal vowels or certain clicks , see e.g. B. under Khoekhoegowab .

literature

  • Mary Seely, Kathryn M. Jacobson, Peter J. Jacobson: Ephemeral Rivers and Their Catchments - Sustaining People and Development in Western Namibia . Desert Research Foundation of Namibia, 1995, ISBN 978-99916-709-4-2
  • HW Stengel: The rivers of the Namib and their inlet to the Atantik - Part II Omaruru and Ugab. Namib Desert Research Foundation, 1966, No. 30. ( available online )
  • Desert Research Foundation of Namibia (Ed.): Omaruru Integrated River Basin Management Project (ORBMP). Windhoek 2005. ( available online )

Web links

Commons : Omaruru-Rivier  - collection of images, videos and audio files

Individual evidence

  1. ↑ Mapping the Major Cathments of Namibia. Ben Ben J. Strohbach, National Botanical Research Institute.