Title : Predicting impact of climate change on water requirements for directly sown rain-fed sweet potato in the semi-arid katumani region, Kenya
In the wake of changing climate, the present water crisis seems to tighten its hold on mankind, hence estimation is an integral part of planning, development and management of water resources of the country based on several hydrological and meteorological parameters. Methodology: The study aimed at predicting the implications of climate change on crop water requirements from 2019 to 2039 in Katumani with the aid of the CROPWAT 8.0 model. CWR were predicted in two scenarios: i) current rainfall and temperature in 2019, ii) rainfall and temperature in 2039 based on Relative Concentration Pathways (RCP); 8.5 and 2.6 scenarios, adopting the global circulation models (GCM) of IPSL-CM5A-MR and GFDL-CM3 for predicting monthly rainfall and temperature, respectively. To achieve effective water allocation and planning, data on sweet potato water requirements, irrigation withdrawals, soil types and climate conditions were gathered in the study area. Assumptions: The study assumed no change in the conditions relating to irrigation and crop production in the future. Results: Sweet potato water requirement in 2019 were modelled at 598.1mm whereas predicted in 2039 under RCP 2.6 and 8.5 to be 634.1 and 639.3mm, respectively. Averagely, an 8.6% decrease in effective rainfall may increase the overall sweet potato WR by 6.9%. This may be due to increased temperature and reduced rainfall. Implication: Short rain season is the most appropriate for production of rain fed crops in Katumani. Conclusion: This study might be useful in explaining the negative effects of climate change on sweet potato water needs in Katumani and aid in planning and management of water resources for many other crops in arid areas.