Estimation of Safe Yield of a Multipurpose Reservoir Using Weap: A Case Study of Thwake Reservoir, Makueni and Kitui Counties, Kenya
Journal of Water Resources and Ocean Science
Volume 7, Issue 4, August 2018, Pages: 60-69
Received: Aug. 13, 2018;
Accepted: Aug. 24, 2018;
Published: Oct. 29, 2018
Views 631 Downloads 56
Christine Nyanchoka Ochengo, Department of Environmental and Biosystems Engineering, University of Nairobi, Nairobi, Kenya
Stephen Conrad Ondieki, Department of Environmental and Biosystems Engineering, University of Nairobi, Nairobi, Kenya
John Paul Obiero, Department of Environmental and Biosystems Engineering, University of Nairobi, Nairobi, Kenya
Follow on us
WEAP (Water Evaluation And Planning) is an integrated water resources planning model developed for more than 25 years by the Stockholm Environment Institute (SEI). In the WEAP model, dam and the water demands (upstream and downstream) are all schematized as an interconnected system ruled by allocation priorities (e.g., dam operation rules, priority for competing demands such as water supply, irrigation, hydropower, environmental flow, water storage in the reservoir). Thwake Reservoir is a multipurpose reservoir for hydropower generation, water supply and irrigation development in Kitui and Makueni Counties. The counties are well known as semi-arid hence the key objective of the study is to estimate the safe yield of the reservoir to enhance effective allocation of the water for different competing demands. Safe yield is based on projected future conditions that include a repeat of the most severe drought of record. Because the definition refers to projected future conditions, safe yield is inherently an estimated characteristic of future conditions that cannot currently be observed or measured. Thus any safe yield is only theoretically available at the time of the estimate. However, the reference to a repeat of the most severe drought of record indicates that past conditions are to be used to project future conditions. In this regard, 1000 years’ synthetic flows were generated using SWAT Model. In the model, 61 years (1952-2012) historical flows were used and the projected flows input into the WEAP model. The monthly reservoir balance for the base scenario and upstream dams development scenario were simulated. The performance of the Thwake Reservoir under different scenarios was assessed. Different sets of scenarios were explored for the Base Case and upstream development dams. These sets were tuned to the operational rules of the Thwake reservoir. Eventually, the dependable yield of the reservoir under different operating rules was estimated for both the base case and the upstream dam development scenarios. Thwake reservoir has an estimated dependable yield when it will be in operation before and after the development of the upstream dams.
Model, Reservoir, WEAP, SWAT
To cite this article
Christine Nyanchoka Ochengo,
Stephen Conrad Ondieki,
John Paul Obiero,
Estimation of Safe Yield of a Multipurpose Reservoir Using Weap: A Case Study of Thwake Reservoir, Makueni and Kitui Counties, Kenya, Journal of Water Resources and Ocean Science.
Vol. 7, No. 4,
2018, pp. 60-69.
Copyright © 2018 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/
) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
S. Saxena and D. S. M. Yadav, “Application of Water Evaluation and Planning Model to Assess Future Water Demands of Surat City,” p. 7, 2016.
O. G. M. Metobwa, K. A. Mourad, and L. Ribbe, “Water Demand Simulation Using WEAP 21: A Case Study of the Mara River Basin, Kenya,” Int. J. Nat. Resour. Ecol. Manag., pp. 9–18, 2018.
J. M. Nyika, G. N. Karuku, and R. N. Onwonga, “Water Balance for Mbagathi Sub-Catchment,” J. Water Sustain., vol. 7, no. 3, pp. 193–203, 2017.
SEI US, “Protecting tropical forest carbon stocks may not prevent large-scale species loss.” Stockholm Environment Institute, 2009.
A. T. Silva and M. M. Portela, “Generation of monthly synthetic streamflow series based on the method of fragments,” 2011, pp. 237–247.
D. C. A. Arselan, “Stream flow Simulation and Synthetic Flow Calculation by Modified Thomas Fiering Model,” no. 4, p. 10, 2012.
J. Jeong, N. Kannan, J. Arnold, R. Glick, L. Gosselink, and R. Srinivasan, “Development and Integration of Sub-hourly Rainfall–Runoff Modeling Capability Within a Watershed Model,” Water Resour. Manag., vol. 24, no. 15, pp. 4505–4527, Dec. 2010.
CASSH, “Annex IV: Water and Sanitation Final design Report.” Oct-2014.
CASSH, “Annex V: Hydropower Design Report.,” Dec-2013.
Amiran, “Draft Pre-feasibility study Report,” 2014.
CASSH, “Component final design Report: Annex VI,” 2013.