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Technical Analysis Of Hydrologic Issues For Dadin Kowa Dam Safety Evaluation
[Full Text]
AUTHOR(S)
Salau, O. B. E., Salaudeen, A.
KEYWORDS
Dadin Kowa dam, hydrologic issues, spillway, safety evaluation, flood routing, attenuate, probable maximum flood, flood frequency analysis, reservoir, penstock, inflow, outflow.
ABSTRACT
A technical analysis of hydrologic issues of the safety evaluation of existing dam (SEED) was performed on Dadin Kowa dam, involving review of initial design basis, flood frequency analysis of new data and flood routing studies with approved probable maximum flood (PMF) through the spillway and outlet works under large discharges. A comparison of the design and new PMF based on data from the gauging station and reservoir inflow data showed the latter to be 2.4 times the former at 2841 and 6879 m3/s respectively. This obviated a review of the hydrologic bases of the design of the spillway and routing of the new PMF through the reservoir. It was found that the reservoir has the capacity to attenuate the new PMF to achieve a peak outflow of 1556 m3/s compared to the design spillway discharge of 1100 m3/s. Operating the spillway, penstock and irrigation release facility simultaneously during the new PMF has no advantage in reducing the peak outflow discharge. A laboratory model of the spillway and chute channel was earlier tested for a maximum outflow of 2000 m3/s and found to be capable. It was therefore concluded that the safety of Dadin Kowa dam with regard to hydrologic issues is satisfactory.
REFERENCES
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[8] Shawmont Ltd (1981) Dadin Kowa Dam project, Comment on UNILAG HRU Spillway Model Study and Flood Hydrology, SMN Site Draft Report, Upper Benue River Basin Development Authority, Yola.
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