Sensitivity of Empirical Equation Parameters for the Calculation of Time of Concentration in Urbanized Watersheds

Abstract

settingsOrder Article Reprints Open AccessArticle Sensitivity of Empirical Equation Parameters for the Calculation of Time of Concentration in Urbanized Watersheds by Jamilton Echeverri-Díaz 1,Óscar E. Coronado-Hernández 2,*ORCID,Gustavo Gatica 3ORCID,Rodrigo Linfati 4ORCID,Rafael D. Méndez-Anillo 2 andJairo R. Coronado-Hernández 5ORCID 1 Departamento de Recursos Hídricos, Sertet SAS, Montería 230002, Colombia 2 Facultad de Ingeniería, Universidad Tecnológica de Bolívar, Cartagena 131001, Colombia 3 Faculty of Engineering—CIS, Universidad Andres Bello, Santiago de Chile 7500971, Chile 4 Department of Industrial Engineering, Universidad del Bío-Bío, Concepción 4030000, Chile 5 Departamento de Productividad e Innovación, Universidad de la Costa, Barranquilla 080001, Colombia * Author to whom correspondence should be addressed. Water 2022, 14(18), 2847; https://doi.org/10.3390/w14182847 Received: 17 August 2022 / Revised: 5 September 2022 / Accepted: 9 September 2022 / Published: 13 September 2022 (This article belongs to the Section Urban Water Management) Download Browse Figures Review Reports Versions Notes Abstract The time of concentration is the time it takes a drop of water in a basin to travel from the most distant point to the outlet, and is one of the most important parameters, along with the morphometric characteristics, for determining the design flow rate in rainfall-runoff models. This study aims to determine the sensitivity of the parameters included in different equations for the calculation of the time of concentration. A case study was conducted on small, urbanized watersheds in the city of Montería, Colombia. The study uses information obtained through field work using GPS equipment and electronic total station, supplemented by geographic information contained in the city drawings of the local sewage company, which includes data on elevations above sea level with sub-metric precision. The time of concentration determined by the 12 empirical equations was compared to the results obtained from the equation proposed by the Natural Resources Conservation Service (NRCS), which was considered as a baseline formulation for the intricacy of calculation. Based on this comparison, it was found that the Carter equation is the one that best fits the results obtained from the NRCS equation because it displayed highly significant goodness of fit values. Even though the equations by Kirpich, Ventura, California Culvert Practice, Simas-Hawkins and TxDOT provide a relatively good fit compared to other empirical equations, they tend to over-estimate time of concentration values, which could lead to the under-estimation of the design flow rates. For this reason, sensitivity analysis of the parameters of these equations represents an alternative for improving the calculation of the time of concentration. The current research analyses deepen the influence of some parameters in the estimation of time of concentration. The research can also be used by designers and engineers in the city of Montería, Colombia, as an important reference to compute time of concentrations in urbanized watersheds.