Projected changes in extreme precipitation indices from CORDEX simulations over Ethiopia, East Africa

Abstract

The projection of precipitation extremes is of significant importance for the reliable management of regional water resources. Thus, this study explores the potential response of the popularly used precipitation extreme indices to the global warming for near future (2011–2040), middle future (2041–2070) and far future (2071–2100) periods, based on the COordinated Regional climate Downscaling EXperiment (CORDEX) Africa experiment outputs over Ethiopia. The results show that the wet (dry) spells were projected to significantly decrease (increase) over most parts of Ethiopia, with relatively longer (shorter) dry (wet) spells projected over the northern parts of Ethiopia. Conversely, the projected changes in extreme precipitation amount above the 95th percentile showed a substantial increase over most parts of Ethiopia, with higher values projected to be in the southern region. The result implies that extreme and heavy precipitation events are likely to be more intense, and could amplify the probability of flood risks, particularly over the southern region. The total and extreme precipitations generally show a strong positive correlation, indicating the increase in extreme precipitation is responsible for the increase in total wet-day precipitation amount in Ethiopia. In general, climate change will have high negative impacts on the dynamics of precipitation patterns over Ethiopia, which could result in more long dry seasons and shorter rainy seasons over most parts of Ethiopia. Thus, the food and water security situation in the region is highly vulnerable due to the projected changes in the intensity and frequency of climate extremes (droughts and floods). However, the increase in precipitation extremes could have the potential to enhance the dry season agricultural productivity of most of the regions in Ethiopia using efficient irrigation systems through excess water harvesting in the rainy season. This can also reduce flood occurrences and hence economic damages. In general, it is of great importance to discuss the socio-economic impacts that could result if increasing precipitation extremes, as well as the increasing (decreasing) trend of maximum length of the dry (wet) spells, continue in the future.