Comparative analysis of flood and rainfall frequency in the ungauged sub-watersheds of Kakia and Esamburumbur in Narok town, Kenya, using the EBA4SUB rainfall-runoff model

Abstract

Knowledge of design peak flow is crucial in various applications related to hydrology, hydraulics and water resources management. However, obtaining design peak flow is challenging especially in ungauged basins lacking of discharge observations, a circumstance that does not allow the calibration of advanced hydrological models. Recently, a new method called EBA4SUB (Event-Based Approach for Small and Ungauged Basins) was introduced to estimate the design peak flow and hydrograph in ungauged basins. The current study used the EBA4SUB model to evaluate the design peak flow in the Kakia and Esamburumbur sub-watersheds, Narok town, Kenya. The study investigated the link between rainfall frequency analysis and flood frequency analysis, showing the reliability of this approach to model at event scale the selected watersheds. The coefficient of determination between the rainfall-based return period and the flow-based return period in both the Kakia and Esamburumbur sub-watersheds highlighted the strong dependency between design rainfall and design peak flow.