Assessment of impact of climate variability/change on inflows to Gaborone dam

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University of Dar es Salaam
The semi-arid Notwane sub-catchment is located in the highly variable climate area affected by Southern Enso-oscillations, and its downstream Gaborone dam reached unprecedented low levels of 5% in the year 2014 since its inception due to low inflows. The main objective of this study was to understand how climate change/variability affect inflows into the dam. Data collected for the study included observed flow, temperature, rainfall, dam levels and abstractions for the period (1966-2014). To fill the missing flow and rainfall data mass balance and correlation methods were used. Data analysis was done as well as the quality and consistency of the data series. Rainfall and flow data series were taken through statistical tests to detect trends and shifts. In an assessment of climate change data of the study area, 9 GCMs were correlated with the observed precipitation to select the best model to extract BSCD downscaled data from. Hydrological modelling was done using HBV and NAM, which were calibrated using observed data. The best performing model HBV was validated and used to generate future flows. The flow data series showed a decreasing trend which is not statistically significant and strong shifts, rainfall displayed statistically insignificant trend with weak shifts. The impact of climate change in flow is that it will decrease by 20%-23% causing water shortage and stress in future.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QC981.8.C5M64)
Climatic changes, River flows, Gaborone dam, Botswana
Molefi, P.N. (2015) Assessment of impact of climate variability/change on inflows to Gaborone dam, Master dissertation, University of Dar es Salaam, Dar es Salaam