Rainfall variability and trends in western Amhara: implication for sustainable water management and agricultural productivity

ABSTRACT Currently, climate change is one of the major challenges facing the global population. Rainfall variability and its unpredictable trends pose significant challenges to water resource management and agricultural productivity in western Amhara, Ethiopia. This study investigated the spatial distribution and temporal trends of rainfall using time-series rainfall data from the Enhancing National Climate Services (ENACTS) from 1991 to 2020. Rainfall variability was assessed using the coefficient of variation, precipitation concentration index (PCI), and standardized anomaly index (SAI). Mann-Kendall and Sen's slope estimator tests were also employed for rainfall trend analysis. The results show that high annual rainfall occurred during the Kiremt (wet) season, and high rainfall variability occurred during the Bega (dry) season in all rainfall grid points over the study area. SAI also witnessed the presence of inter-annual variability of rainfall with negative and positive anomalies in 46.7 and 53.3% of the reference years, respectively. Trend analysis results showed an overall non-significant increasing trend in the annual and seasonal rainfall (except Bega) during the study period. Hence, this study provides information about the spatial distribution of rainfall at different timescales, and it is crucial for water resource planners and design professionals in urban drainage, bridges, dams, and agricultural sectors.