Assessing impacts of future climate on the crop water requirement and growth period. A case of Lake Hawassa watershed, Ethiopia

Background: Assessing the influence of climate change on the crop growth period, water requirement, and drought conditions is important for the integrated planning of the production system. This study assessed the impact of climate models from the Coupled Model Inter-comparison Product (CMIP5) on Crop Water Requirement (CWR), Length of Growth Period (LGP), and drought conditions. This study applied two regional climate models that have shown better performance for the evaluation criteria during the historical period. Drought analysis was conducted for different classes of drought index using standardized anomalies of rainfall (S-index) from climate models. Results The future growing season of the area on average for all the years is between April 15 and May 1. The period between April 15 and May 1 marks the onset time and the end of September is the cessation time having LGP ranging from 150–160 days. Crop water requirement was projected to increase on average from the base period on both RCP 4.5 and RCP 8.5 scenarios. Analysis of drought prediction shows a few cases of extreme drought during the 2050s and 2080s under RCP 8.5. Furthermore, the 2050s has registered the lowest number of years with a positive S-index value indicating the projected scarcity of precipitation during these periods under RCP 8.5. Conclusion This study provides information on the impacts of climate change on crop growth periods, water requirements, and drought conditions. Therefore, understanding their future changes will enable the preparation of a better plan for the adaptation and mitigation of impacts.