Rainfall-runoff modeling: A modification of the EBA4SUB framework for ungauged and highly impervious urban catchments

Abstract

There are no doubts that prediction of runoff is one of the crucial hydrological research topics when dealing with catchments. It is noteworthy that the rapid land use change in catchments due to urbanization strongly modifies runoff formation, and the use of many common rainfall-runoff models often is not appropriate in such situations. Moreover, in small catchments with a high percentage of impervious areas, highly detailed hydrometeorological data are needed to calibrate the parameters of advanced rainfall-runoff models. Facing the new challenges of urban catchment runoff, this work presents a modification of the EBA4SUB (Event-Based Approach for Small and Ungauged Basins) rainfall-runoff model to improve its applicability in urban areas. The proposed approach is a combination of the original model with a newly formulated excess rainfall calculation (named P4URB) that considers pervious and impervious areas. Indeed the original EBA4SUB model does not consider impervious areas as a separate form of land use. Based on results, we can conclude that EBA4SUNURB (Event-Based Approach for Small and UNgauged Urban Basins) is better suited for urban catchments because it includes a more rational depiction of how impervious areas influence runoff formation. The shape of the design hydrograph and related peak flow are significantly different from those generated from the commonly used Nash model. The main advantage of EBA4SUNURB model is that it can be used in ungauged catchments because all parameters are calculated based on catchment characteristics as opposed to being estimated through a calibration process.