Davi De Carvalho Diniz Melo,Cristiano das Neves Almeida,Uiara Talitta Martins de Araújo,Victor Hugo Rabelo Coelho,Alain Marie Bernard Passerat de Silans, Universidade Federal da Paraíba, Dep. de Eng. Civil e Ambiental, almeida74br@yahoo.com.br
ABSTRACT
Due to several factors, rating curves have been used for estimating flow in river channels. Although it consists of a simple method and frequently gives good results, some cares must be considered before making use of the calculated discharges. In this study, discharges calculated by conventional rating curves and by the Manning`s equation were compared as well as the possible errors caused by using those approximations. The study was carried out in a discharge gauge installed in Mamuaba river, in Paraíba State, since the beginning of project BEER (Experimental and Representative Watersheds in Semi-Arid). Results show that, for the study area, both methods had equivalents results for the most part of the analyzed period. On another analysis, concerning the modifications occurred at the monitored river cross section, it was observed that, due to a destabilization of the cross section geometry, the quality of the results estimated by the rating curves were negatively affected. Finally, the influence of rainfall events over the geometric stability of the studied river cross section is analyzed.
PALAVRAS CHAVE: curva-chave, medições de vazão, equação de Manning.