The Potential of Rainwater Harvesting: A Case of the City of Windhoek, Namibia
Journal of Water Resources and Ocean Science
Volume 2, Issue 6, December 2013, Pages: 170-174
Received: Nov. 20, 2013;
Published: Dec. 10, 2013
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Festus Panduleni Nashima, University of Namibia, Private Bag 13301, Windhoek, Namibia
Martin Hipondoka, University of Namibia, Private Bag 13301, Windhoek, Namibia
Inekela Iiyambo, Rossing Uranium of Namibia, Private Bag 5005, Swakopmund, Namibia
Johannes Hambia, University of Namibia, Ogongo Campus, Private Bag 5520, Oshakati, Namibia
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Windhoek, Namibia’s capital has experience for more than 25 years of novel approaches in integrated water management largely driven by the scarcity of water in the area. Notably absent in their approaches however, is the rooftop rainwater harvesting which is regarded as one of the viable alternative sources of water for domestic use. This paper assesses the potential economic benefits for rooftop rainwater harvesting for the City of Windhoek. The rooftop areas from four representative formal suburbs of Okuryangava (low income) in the north, Academia (middle income) in the south-central, Pioneers Park (middle income) in the south-west and Ludwigsdorf (high income) in the east, were estimated from high resolution satellite images captured from Google Earth. These estimates were used to extrapolate for the potential amount of rainwater that can be harvested in an average rainy season (i.e. December to April) in the study area. The estimated harvestable amount for each residential area was developed using a simple model that incorporates total rooftop area and estimated rainwater. The derived figure was then expressed in terms of cost per unit prices charged by the City of Windhoek. Pioneers Park attests to have the highest (134 m3) potential harvestable rainwater per household, while Okuryangava is estimated to harvest the least amount of 36 m3 per raining period. Given the high density of erven, however, Okuryangava has a potential to harvest approximately 920484 m3 of water per hectare, ranking this suburb second after Academia, which stands at 1120716 m3. This is a significant amount of water effectively taken from rainwater rooftop that could also provide justifiable saving to residents if used instead of tap water. It is therefore recommended that the City of Windhoek actively promotes rooftop rainwater harvesting for the benefit of residents and also as a measure to reduce storm-water runoff due to urban development.
City of Windhoek, Rooftop Area, Rainwater Harvesting, Water Saving Cost
To cite this article
Festus Panduleni Nashima,
The Potential of Rainwater Harvesting: A Case of the City of Windhoek, Namibia, Journal of Water Resources and Ocean Science.
Vol. 2, No. 6,
2013, pp. 170-174.
S. Baker, E. Grygorcewicz, G. Opperman and V. Ward. "Rainwater Harvesting in the Informal Settlements of Windhoek, Namibia". Retrieved 31 March 2011, from website: http://www.wpi.edu/Pubs/E-project/Available/E-project-051207-152911/unrestricted/report.pdf, 2007.
B.B. Bhandari. "What is happening to our Freshwater Resources? Institute for Global Strategies. Environmental Education project". Tokyo, 2003.
City of Windhoek. "City Development and Planning". Retrieved 7 April 2010, from website: http://www.windhoekcc.org.na/default.aspx?page=42, 2010.
VV. Berlag. "Rainwater harvesting facilities part 1: design, construction, operation, and maintenance". Berlin, Deutsches Institut für Normunge (DIN), 2002.
Habitat Research & Development Centre (HRDC). "Rainwater Harvesting in Namibia". Newsletter of the Namibia National habitat committee Vol. 3, No. 3, 2007.
D. Louw. ‘’The Windhoek Aquifer: An important source in the water supply to the City of Windhoek’’. Namibia Scientific Society. Windhoek. 2013. (Presentation).
B.S. Mapani and U. Schreiber. "Management of city aquifers from anthropogenic activities: Example of the Windhoek aquifer, Namibia". Journal of Physics and Chemistry of the Earth, volume 33, 674-686, 2008.
E.C. Murray and G. Tredoux. "Planning Water Resource Management: The Case for Managing Aquifer Recharge". Proceedings of the 2004 Water Institute of Southern Africa (WISA) Biennial Conference, 2 – 5 May 2004. Cape Town. 430-437, 2004.
J. MwengeKahinda, A.E. Taigbenu and R.J. Boroto. "Domestic rainwater harvesting to improve water supply in rural South Africa". Physics and Chemistry of the Earth, 32: 1050-1057, 2007.
New Era. "Harvesting rainwater in Windhoek a cheaper option". Retrieved 10 November 2012, from website: http://www.infrastructurene.ws/2012/07/03/harvesting-rainwater- in-windhoek-a-cheaper-option/, 2012.
NORIT. "New Goreagab Water Reclamation Plant". Retrieved 7 April 2010, from website: http://www.norit.com/import/assetmanager/5/5565/02- CASE_HISTORY_GoreangabB.pdf\, 2002.
Romsey. "Rainfall harvesting calculator". Retrieved 12 February 2011, from website: http://home.iprimus.com.au/foo7/tank2.html, 2010.
T. Uhlendahl, D. Ziegelmayer, A. Wienecke, L. Mawisa and P. du Pisani. "Water consumption Windhoek 2010". Institute of Cultural Geography, Berlin: Albert-Ludwigs University of Freiburg, 2010.
United Nations Food and Agriculture Organization (UNFAO). "Coping With Global Water Scarcity". Rome, FAO, 2007.