Assessment of the Past and Future Meteorological Drought Characteristics in the Eastern Province of Rwanda Under a Changing Climate

Abstract

The Eastern province of Rwanda faces frequent droughts in its low-lying areas, which may lead to severe negative effects on agriculture and livestock production during extreme climate conditions. This study aims at assessing the past and future drought characteristics in the Eastern Province of Rwanda under a changing climate. The monthly gridded rainfall dataset known as ENACTS dataset for a period of 39 years (1981 to 2019) and monthly rainfall dataset from CORDEX-Africa-22 Domain for the period starting from 1981 – 2100 from the Earth System Grid Federation (ESGF) portal were used. The data were analyzed using Standardized Precipitation Index (SPI) in order to characterize the past drought over the Eastern Province of Rwanda based on the seven locations. Furthermore, the analysis of the temporal and spatial variability of rainfall amount, frequency and duration were carried out over the study region. Later, Future drought characteristics were analyzed based on the CORDEX-Africa-22 projection of the validated models on two Representative Concentration Pathways (RCPs) namely RCP2.6 and RCP8.5. Finally, a comparative study between the past and future drought was done in order to understand changes in frequency and severity of the drought over the Eastern Rwanda. Based on the historical data, the results indicated that Nyagatare station faced 22 years out of 39 of no droughts from 1981 – 2019. Again, Nyagahanga and Nyamata did not experience droughts in 21 years out of the 39 years. Kawangire station in Kayonza district and Rwamagana experienced drier years than any other location, which are 22 out of 39 years based on 12 months-SPI. The most severe drought was recently experienced during the year of 2017 and it was drier across all the seven locations with mild to extreme droughts. Based on Projected data, Nyarubuye followed by Kibungo Kazo will be the driest locations with only 8 and 9 years out of 26, respectively experiencing no drought while the rest of the years reported mild to extreme droughts under RCP2.6 from 2022-2047. Further, regarding the drought frequency from 2048 - 2073 over each location in the Eastern Province under RCP2.6, the study concludes that Kawangire and Rwamagana will experience drier seasons with only 14 years out of the 26 year-period exhibiting no droughts. Moreover, on the drought frequency from 2074 - 2099 under RCP2.6, Kibungo Kazo will only have 12 no drought years out of 26 years.