Occurrence and magnitude of extreme climatic events in lake hawassa catchment, Ethiopia

Abstract

Africa is the most vulnerable continent in the world; which recurrent droughts, extreme temperature and rainfall affects agriculture and food security. This study examined the frequency and intensity of extreme climatic events in the Lake Hawassa catchment in Ethiopia from 1981 to 2022. The gridded data were analyzed using SPEI index, Mann-Kendall test, and R-climax packages to detect frequency, trend changes, and intensity. The Wondo Genet station experienced severe drought with SPEI3 and SPEI12 values of -2.8 and -3.02, respectively. Yirba Duwancho station showed the highest extreme rainfall with SPEI3 and SPEI12 values of 2.8 and 2.58, respectively. The extreme temperature indices (TXx, TNx, TNn, TX90p, and WSDI) exhibited statistically significant (α=0.05) increasing trends at each station. The Yirba Duwancho station showed a statistically significant (α=0.05) increase in the majority extreme rainfall indices. Hawassa and Shashemene stations exhibited significant (α=0.05) increases in TNn, TX90p, and WSDI. Wondo Genet station experienced substantial increases in the TX90p and WSDI. Increasing trend in several extreme rainfall indices of RX1day, RX5day, SDII, R10, and R20 was observed at Hawassa station. Hence, our findings underline the urgent necessity of climate smart agriculture, better weather forecasting instruments, and eco-hydrological monitoring programs to build resilience to extreme drought events in the catchment and impelementing soil and water conservation activities, agroforestry, buffer zone around lake Hawassa to mitigate siltation problem in the Lake Hawassa.