Authors : Adimasu Woldesenbet Worako, Alemseged Tamiru Haile, Meron Teferi Taye
DOI : 10.1016/j.ejrh.2021.100817
Volume : 35
Issue : 1
Year : 2021
Page No : 100817
Study Region: The Ethiopian Rift Valley Lakes basin is found in the main Ethiopian Rift Valley system. Study Focus: Understanding the hydrological impact of El Nino-Southern ˜ Oscillation (ENSO) is of a paramount importance for society since it substantially affects the environmental and socioeconomic conditions. The relation between ENSO indicators (SOI, MEI and Nino3.4) ˜ and streamflow magnitude was statistically evaluated with partial correlation, cross correlation, extreme streamflow indices and streamflow deficits to provide empirical evidence on how ENSO phases (La Nina ˜ and El Nino) ˜ affect streamflow variability. Trends of streamflow and ENSO indicators were tested using the non-parametric Mann-Kendall test. New Hydrological Insights for the Region: Our findings indicate that the partial correlation between the catchment area and ENSO effect on streamflow were not statistically significant at p < 0.05 after removing the south-north gradient. The direction of the ENSO effect is spatially inconsistent since El Nino ˜ (La Nina) ˜ causes positive deviation in some catchments and negative deviation for other catchments. Though statistically insignificant, reduced flow is detected for many catchments during El Nino ˜ years. For most catchment, the extreme high flow has a larger magnitude during La Nina ˜ than El Nino ˜ whereas the extreme low flow has a larger magnitude during El Nino ˜ than La Nina ˜ years. Overall, the relationship between ENSO and streamflow of the study area is found spatially inconsistent and statistically insignificant for most catchments.