Analysis of hydrological connectivity in the Tietê-Jacaré hydrographic basin – São Paulo state, Brazil

Abstract

The connectivity study is essential for the comprehension of various ecological processes, but it is poorly studied in aquatic environments, where hydrological connectivity is understood as the transfer of water, energy, and organisms from one part of the landscape to another. This work aims to analyze the hydrological connectivity present in the territory of the Tietê-Jacaré Hydrographic Basin - SP, through the application of the Hydrological Connectivity Index, to evaluate the dynamic and temporal process of these structures in 2007 and 2017. Geographic Information Systems (GIS) techniques were applied with the application of integration theory to investigate which rivers, wetlands, lakes, dams are connected. From 2007 to 2017, a reduction of 8,686.42 to 8,686.42 km was observed, totaling 208.35 km of the drainage network. There was also a loss of 163.77 km of springs (24.10%) and a reduction in the number of interactions between the hydrological network from 7,214 to 5,303. The updating of the information on the water resources extension complemented by the application of the indices, by expressing the state of landscape configuration, were important tools in the diagnosis of ecosystem conservation, enabling accurate analysis of the elements that compose them. The hydrographic basin showed a reduction in the drainage network in all regions, which consequently resulted in changes in the patterns of hydrological connectivity, reducing the number of connections by almost half. These factors must be analyzed in detail concerning the planning of the hydrographic basin, mainly related to the future of the quantity and quality of water resources.