Assessment of Potential Changes in Hydrologically Relevant Rainfall Statistics over the Sondu River Basin in Kenya Under a Changing Climate
Volume 9:1
Rwigi, Stephen Kibe, Nzioka John Muthama, Alfred Owour Opere and Franklin Joseph Opijah
Department of Meteorology, University of Nairobi, Nairobi, Kenya
Corresponding Author
Rwigi, Stephen Kibe,
Department of Meteorology, University of Nairobi,
email: This email address is being protected from spambots. You need JavaScript enabled to view it.; phone: 0722693046
(Received 1 April 2016, in revised form 9 May 2016, Accepted 31 May 2016)

Scenarios of past, present and intermediate future climates for Sondu River basin were analysed in this study to evaluate the potential changes in hydrologically relevant rainfall statistics that are likely to be observed by the middle of this century as a result of climate change. These climate scenarios were developed by applying dynamical downscaling of the relatively course resolution climate scenarios simulated by the fourth generation coupled Ocean-Atmosphere European Community Hamburg Model (ECHAM4) using the Providing Regional Climates for Impacts Studies (PRECIS) modelling system. The regional climate scenarios, which were available at a daily time-step and a spatial grid resolution of 0.5˚ over the Eastern Africa region, were matched to the Sondu river basin in the western region of Kenya. The possible hydrological impacts of climate change were assessed by applying the scenarios in a daily time-step hydrological model. The analysis of hydrologically relevant rainfall statistics focussed on determining changes in rainfall patterns and the likely hydrological implications to the basin. The results indicated that more rainfall is projected for the region in the immediate and intermediate future in form of increased seasonal rainfall during the December-January-February (DJF), March-April-May (MAM) and September-October-November (SON) seasons resulting from increased number of days of rainfall and higher probabilities of a wet day following a dry day in a month. Based on these scenarios, the combination of the wetter antecedent conditions and the more rain days in a month will result in more surface runoff being generated which will not only have implications on the water balance but also the water quality in the basin.
Key Words: climate change, climate scenarios, climate modelling, climate downscaling, Sondu Basin, Kenya

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