Importance of adequate appropriation of physiographic information for concentration times determination

Importância de adequada apropriaçãode informações fisiográficas para definição de tempos de concentração

Abstract

Concentration time is an important parameter for drainage systems design and is closely related to the physiographic characteristics of a given hydrographic basin. Information from cartographic bases or images obtained by remote sensing, which present certain scales/resolutions, are often employed for the appropriation of concentration times. The present study sought to investigate the influence that the combination of different physiographic information, in different scales, and different calculation methods can produce in concentration times’ values. The applied methodology included a concentration times appropriation methods survey, identification of methods compatible with the study area characteristics, physiographic variables appropriation from information plans at different scales and concentration times determination for different regions. The results show that there is an equivalence between Tulsa District and US Corps of Engineers methods, and that these methods produce higher concentration times estimates than those produced by the George Ribeiro method. For the study area, the maximum calculated relative error was 52%.

Keywords:
concentration time; drainage; hydrology; scale; watershed.