HYDROLOGICAL (DIS)CONNECTIVITY ALONG THE LONGITUDINAL PROFILE OF THE DUAS BOCAS RIVER (ES)

Abstract

Hydrological connectivity is a theoretical approach to investigating energy and matter flows in river basins. This study aims to analyze the hydrological (dis)connectivity concerning the different land uses and land covers, as well as the effect of the Duas Bocas dam and its water supply reservoir along the longitudinal profile of the Duas Bocas River (Great Vitória, ES, Brazil). Between august 2016 and 2017, monthly fluvial water samples for the analysis of total nitrogen, phosphorus, and suspended solids (SS), in addition to flow measurements, were taken at four sampling sites along the fluvial network (82,8 km²). The land use and land cover of the effective drainage areas were obtained from the orthophoto mosaic of 2012/2015 (1:10,000). The results show that forest cover is essential to reducing the contents of nutrients and SS in the DB01 site upstream of the reservoir. The Duas Bocas dam fragments the longitudinal hydrology, mainly affecting the DB02 sampling site located downstream. The highest contents of suspended sediments and nutrients indicate longitudinal hydrological connectivity of the river with the land use of pasture and agricultural land. Hydrological connectivity highlights the importance of analyzing energy and matter flows in catchments.