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Journal of Environmental Hydrology
ISSN 1058-3912 |
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The Open Access Electronic Journal of the
International Association for Environmental Hydrology JEH Volume 21 (2013), Paper 2 Posted March 16, 2013 LOW FLOW ANALYSIS OF THE BLACK VOLTA RIVER AT LAWRA IN GHANA
K. Kankam-Yeboah1 2Pacific Institute, Oakland, California, USA ABSTRACT A flow duration curve was developed and the minimum flow determined for the Black Volta Basin using mean daily streamflow at Lawra. The result showed that streamflows of 1.24 m³/s and 0.368 m³/s were equaled or exceeded 95% and 99% of the time, respectively at Lawra. Groundwater contribution to streamflows in the basin was very low with estimated baseflow index of 0.01. This may be attributed to the basin being underlain by low permeable aquifers with low storage capacities. The result also showed with 100% probability that streamflow of 0.19 m³/s is expected to occur in the basin at least once every year at Lawra. Various distribution functions including Normal, Lognormal, Weibull, Gumbel and Gamma distributions were fitted to the mean daily low streamflows. The Normal distribution was found to produce the best fit to the low streamflows with NSE equaled to 98.43%. Low streamflow in the basin had a small tendency to produce unusual extreme low flow. The probability of occurrence of low streamflows in the basin was low and daily water abstraction below 1.24 m³/s is considered reliable and sustainable in terms of water supply for domestic, industrial and agricultural uses. Reference: Kankam-Yeboah, K., F.Y. Logah, B. Amisigo, E.O. Bekoe, D. Ofori, and J.A. Akudago. 2013. Low flow analysis of the Black Volta River at Lawra in Ghana. Journal of Environmental Hydrology, Vol. 21, Paper 2. CONTACT: Kwabena Kankam-Yeboa CSIR Water Research Institute P.O. Box M. 32 Accra, Ghana E-mail: kyeb59@yahoo.com |
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