“Multivariate analysis of baseflow index in complex rift margin catchments: The case of Abaya-Chamo lakes basin, southern Ethiopia”

Abstract

In developing countries, there is high limitation and irregularity in river flow data recording, and a significant number of hydrologic basins are ungauged. Despite the fact that the estimation of surface and groundwater asset assumes the measurements as a basic concern in resource management and planning. Understanding baseflow forms specifically as a piece of the total flow of river basins can be utilized as a demonstrative tool to portray hydrologic frameworks and turns into a basic issue of water balance contemplates. Hence, this work seeks to compare baseflow estimates in the Abaya-Chamo Lakes Basin using baseflow separation algorithms (such as River Analysis Package (RAP), Time Plot (TP) and Kille (K)). The assessments are then utilized to set up and establish further the associations with multivariate factors (such as climate, geomorphometric, land use cover and aquifer properties). Indeed, an accessible 16 daily river discharge records were therefore used to estimate the value of the Baseflow Index (BFI). The estimates from both River Analysis Package and Time Plot algorisms are more hydrologically plausible and compared well to each other with a linear correlation coefficient of 0.96. In any case, the graphical Kille method is somehow underestimated the baseflow yield. The estimated value over whole ranges between 0.29 and 0.62, which suggests about 42% of the long-term total river flow, is a contribution of groundwater discharge. Furthermore, this index was gathered with multivariate's to have a consistent causal explanations as a descriptor of the hydrological framework, and have a significant positive coefficient of correlation with slope, elevation, forest land use cover hypsometric integral, rock age and plateau physiographic sub-section with its prevailing climatic conditions, and while, negative correlation with grassland use cover and escarpment physiographic sub-section. This study, therefore, explicitly revealed that the evolution of geomorphological features in the plateau (physiographic subsection with associated elevation, hypsometric integral, drainage density, and climatic features were found to be the dominant control of the baseflow yield over other multivariate's (such as land cover and aquifer properties). The stepwise regression equation for lakes basin based on multivariate attributes is used as proxy knowledge to ungauged basins to estimate baseflow yield with considerable caution because of the heterogeneity in various variables.