Wetlands Ecology and Management

, Volume 20, Issue 5, pp 389–398 | Cite as

The role of vegetation in the water budget of the Usangu wetlands, Tanzania

  • E. KihweleEmail author
  • B. Mnaya
  • G. Meng’ataki
  • C. Birkett
  • E. Wolanski
Original Paper


The Usangu wetlands were severely degraded over the last twenty years by cattle and the shortage of water due to rice irrigation upstream. The eastern Usangu wetlands that were previously perennial dried out in 2000 and 2002 in the dry season. Following the removal of cattle in 2006 from the eastern Usangu wetlands, perennial wetlands has re-established itself and in 2011 the vegetation had recovered and covered about 95 % of the wetted surface mainly as floating vegetation. These wetlands are the source of water of the Great Ruaha River and the volume of water entering the river has nearly doubled after cattle removal. We suggest that this may be due to the shading effect of the floating vegetation reducing the loss of water through net evaporation to about 0.5 cm day−1 as opposed to about 1 cm day−1 for open water evaporation in this tropical climate. This suggests the important role of the biology in controlling the water budget. By contrast cattle and rice farms have not been removed from the western Usangu wetlands, located upstream, where the wetlands are now reduced to small areas fringing the rivers. We suggest that the western Usangu wetlands should also be restored in order to further increase flows in the Great Ruaha River. At the same time water governance in the catchments and irrigation areas upstream of Usangu wetlands is also urgently required because present water yields are insufficient to meet the hydroelectric needs of Tanzania, the water users all along the river, as well as the important coastal wetlands associated with the Rufiji Delta during a drought year.


Water budget Vegetation cover Radar altimetry Surface water height Irrigation Cattle Evaporation 



This study was supported by Tanzania National Parks and by the NASA grants NNX08AT88G and NNX08AM72G.


  1. Bauer P, Thabeng G, Stauffer F, Kinzelbach W (2004) Estimation of the evapotranspiration rate from diurnal groundwater level fluctuations in the Okavango Delta, Botswana. J Hydrol 288:344–355CrossRefGoogle Scholar
  2. Birkett CM (1998) Contribution of the TOPEX NASA radar altimeter to the global monitoring of large rivers and wetlands. Water Resour Res 34:1223–1239CrossRefGoogle Scholar
  3. Canisius F, Turral H, Mbilinyi BP (2011) Analysis of seasonal land use in Usangu wetlands, Tanzania: an object-oriented technique for multi-temporal analysis with high resolution data. Int J Remote Sens 32:1885–1900CrossRefGoogle Scholar
  4. Crisman TL, Chapman LJ, Chapman CA, Kaufman LS (2003) Conservation, ecology, and management of African fresh waters. University Press of Florida, Gainesville, p 514Google Scholar
  5. de Villiers M (2000) Water: the fate of our most precious resource. Houghton Mifflin Company, Boston, p 352Google Scholar
  6. Elisa M, Gara JI, Wolanski E (2010) A review of the water crisis in Tanzania’s protected areas, with emphasis on the Katuma River–Lake Rukwa ecosystem. Ecohydrol Hydrobiol 10:153–166CrossRefGoogle Scholar
  7. Kashaigili JJ, McCartney MP, Mahoo HF, Lankford BA, Mbilinyi BP, Yawson DK, Tumbo SD (2006) Use of a hydrological model for environmental management of the Usangu Wetlands, Tanzania. IWMI Research Report 104, IWMI, p 41Google Scholar
  8. Lankford B, van Koppen B, Franks T, Mahoo H (2004) Entrenched views or insufficient science? Contested causes and solutions of water allocation; insights from the Great Ruaha River Basin, Tanzania. Agric Water Manag 69:135–153CrossRefGoogle Scholar
  9. Mnaya B, Kiwango Y, Gereta E, Wolanski E (2011) Ecohydrology-based planning as a solution to address an emerging water crisis in the Serengeti ecosystem and Lake Victoria. In: Elliot HS, Martin LE (eds) River ecosystems: dynamics, management and conservation, NOVA Science Publishers, pp 233–258. ISBN:978-1-61209-145-7Google Scholar
  10. Mohamed YA, Savenije HHG, Bastiaanssen WGM, van den Hurk BJJM (2005) New lessons on the Sudd hydrology learned from remote sensing and climate modelling. Hydrol Earth Syst Sci Discuss 2:1503–1535CrossRefGoogle Scholar
  11. Mtahiko MGG, Gereta E, Kajuni AR, Chiombola EAT, Ng’umbi GZ, Coppolillo P, Wolanski E (2006) Towards an ecohydrology-based restoration of the Usangu wetlands and the Great Ruaha River, Tanzania. Wetl Ecol Manag 14:489–503CrossRefGoogle Scholar
  12. Mwakalika S (2011) Assessing the hydrological conditions of the Usangu wetlands in Tanzania. J Water Resour Prot 3:876–882CrossRefGoogle Scholar
  13. Postel S, Richter B (2003) Rivers for life: managing water for people and nature. Island Press, Washington DC, p 220Google Scholar
  14. Saunders M, Lewis P, Thornhill A (2007) Research methods for business students, 4th edn. Prentice Hall, LondonGoogle Scholar
  15. SMUWC (2002) Usangu water resources. Technical reports, final draft reportGoogle Scholar
  16. WWF (2010) Assessing environmental flows for the Great Ruaha River and Usangu Wetland, Tanzania. WWF Tanzania Country Office (WWF-TCO), pp 274Google Scholar
  17. Yawson DK, Kachroo RK, Kashaigili JJ (2004) Failure of the Mtera–Kidatu reservoir system in the early 1990s. IWMI Research Report, IWMI, pp 12Google Scholar

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • E. Kihwele
    • 1
    Email author
  • B. Mnaya
    • 2
  • G. Meng’ataki
    • 3
  • C. Birkett
    • 4
  • E. Wolanski
    • 5
  1. 1.Serengeti National ParkTANAPAArushaTanzania
  2. 2.TANAPAArushaTanzania
  3. 3.Ruaha National ParkTANAPAIringaTanzania
  4. 4.ESSICUniversity of MarylandCollege ParkUSA
  5. 5.School of Marine and Tropical BiologyJames Cook UniversityTownsvilleAustralia

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