Assessment of surface water resources in Great Ruaha River sub-basin Tanzania: Application of WEAP model for water allocation and utilization impacts analysis

Rose Gervas, Deogratias M.M. Mulungu, Joel K. Nobert


The Great Ruaha River (GRR) sub-basin is one of the most important waterways in Tanzania as it supports important economic activities. The sub-basin is progressively faced with an inevitable situation of increasing water demand among competing users while the quantity and quality of water is diminishing. The focus of this study was to assess allocation of existing (2012) and future (up to 2025) quantities of surface water in the GRR sub-basin with consideration of priorities given in the Tanzania Water Resources Management Act, 2009 in the order: domestic, environment, agriculture, livestock and non-domestic. Simulation of water allocation scenarios of irrigation expansion (IE) and implementation of environmental flow requirements (EWD) and their impacts on met demands was done by using WEAP model. Results showed that under current and future conditions, available streamflows are sufficient for the first two water use priorities. Implementation of EWD and IE scenarios will change demands in comparison with reference scenario by 80%, -38% and 45% and shortages by 147%, 123% and 13% in Little Ruaha, Ndembera and Kisigo catchments respectively. To eliminate water shortages, construction of reservoirs, use of alternative supply sources (especially in agriculture) and water demand management measures are recommended.

Keywords: Great Ruaha River, Rufiji basin, scenarios, water allocation, water shortage, WEAP model.

Full Text:



Arranz R. and McCartney M. (2007). Application of the Water Evaluation and Planning (WEAP) model to assess future water demands and resources in the Olifants catchment, South Africa,

Colombo, Sri Lanka. IWMI working paper 116: International Water

Management Institute.

Chanzi G. (2017). Assessment of Water Availability and Uses at Kilombero Basin Using SWAT and WEAP Models. MSc Dissertation in Water Resources Engineering, Department of Water Resources Engineering, University of Dar es Salaam, Tanzania.

DHI Water and Environment (2006). MIKE Basin Simulation Model: A Versatile Decision Support Tool for Integrated Water Resources Management and Planning Horshelm, Denmark. Retrieved on 29th July 2013.

Gervas R. (2013). Analysis of water resources allocation in the Great Ruaha River sub-basin, Tanzania. Master of Integrated Water Resources Management, Department of Water Resources Engineering, University of Dar es Salaam, Tanzania.

Kadigi R.M.J., Kashaigili J.J. and Mdoe N.S. (2004). The economics of irrigated paddy in Usangu Basin in Tanzania: Water utilization, productivity, income and livelihood implications. Physics and Chemistry of the Earth, 29(15-18): 1091-1100.

Kashaigili J.J., Kadigi R.M.J., Lankford B.A., Mahoo H.F. and Mashauri D.A. (2005). Environmental flows allocation in river basins, Exploring allocation challenges and options in the GRR

catchment in Tanzania, Physics and Chemistry of the Earth, Parts A/B/C, 30(11-16): 689-697.

Kashaigili J.J., Mc Cartney M.P., Mahoo H.F, Lankford B.A., Mbilinyi B.P., Yawson D.K. and Tumbo S.D. (2006). Use of a hydrological model for environmental management of the Usangu Wetlands, Tanzania. Research Report 104, Colombo Sri Lanka: International Water Management Institute, 48 p. Doi:

Kishiwa P., Nobert J., Kongo V. and Ndomba P. (2018). Assessment of impacts of climate change on surface water availability using coupled SWAT and WEAP models: Case of Upper Pangani River Basin, Tanzania. Proceedings of the International Association of Hydrological Sciences 378: 23-27.

Lankford B. (2002). Irrigation, livelihoods and river basins, LADDER Working Paper No. 14. ODG, Norwich, UK.

Lankford B.A., van Koppen B., Franks T. and Mahoo H.F. (2004). Entrenched views or insufficient science? Contested causes and solutions of water allocation; insights from the Great Ruaha River Basin, Tanzania. Agricultural Water Management 69(2): 135-153.

McCartney M.P., Yawson D.K. and Huber-Lee A. (2005). Simulating water resources development in the Olifants catchment, South Africa. IWMI Theme 1, Working Paper (Draft). International Water Management Institute (IWMI).

Mbungu W.B. and Kashaigili J.J. (2017). Assessing the hydrology of a data- scarce tropical watershed using the Soil and Water Assessment Tool: Case of the Little Ruaha River Watershed in

Iringa, Tanzania. Open Journal of Modern Hydrology, 7: 65-89.

Mulungu D.M.M. and Taipe C.L.R. (2012). Chapter 2: Water evaluation and planning in the Wami River Basin: Application of the WEAP model in Bioenergy and Food Security, the BEFS Analysis for Tanzania. Edited by E. Beall, FAO 54, ISSN 2226 – 6062.

Munkyala D. (2017). Assessment of surface water resources potential and its allocation in Ndembera catchment, Rufiji basin. Master of Integrated Water Resources Management, Department of Water Resources Engineering,

University of Dar es Salaam, Tanzania. Mwakalila S. (2005). Water Resources Management Guidelines in Ruaha Basin, Tanzania, Conference paper h041160, International Water Management Institute, 18p..

Perera B.J.C, James B. and Kularathna M.D.U. (2005). Computer software tool REALM for sustainable water allocation and management, Journal of Environmental Management, 77: 291- 300.

Pyrce R. (2004). Hydrological low flow indices and their uses. WSC Report No. 04-2004, Watershed Science Centre (WSC), Trent University, Peterborough, Canada, 50p.

Sieber J., Huber-Lee A. and Raskin P. (2002). WEAP: Water Evaluation and Planning System User Guide (for WEAP 21), Stockholm Environmental Institute-Boston, and Tellus Institute.

Sieber J., Yates D., Huber Lee A. and Purkey D. (2005). WEAP: a demand priority and preference driven water planning model: Part 1, model characteristics. Water International, 30(4): 487–500.

SMUWC (2001). Sustainable Management of the Usangu Wetland and its Catchment. Supporting Report 12: Groundwater. A report to the Ministry of Water and Livestock.


  • There are currently no refbacks.