Relevance of field data in the assessment of structural and functional sediment connectivity in a small catchment of southern Brazilian plateau

Abstract

Hydrological and sedimentological dynamics are controlled by hillslope‐channel (de)coupling, which is influenced by several natural and anthropogenic factors. However, studies on sediment connectivity are recent and present numerous challenges to be overcome. Furthermore, there is a need to explore and identify sediment connectivity governing processes and phenomena. In this study, hydrological monitoring and indices application were used to access aspects of sediment connectivity in a small catchment (0.89 km2), located on a plateau in southern Brazil. The indices are a combination of variables conceptually known as controllers of the spatial and temporal organization of sediment flows in the system. The application of these tools proved to be relevant for the characterization of structural and functional connectivity of the study area. The tools applied were structural index of connectivity (IC); index of hydrosedimentological connectivity (IHC), based on observed events; field connectivity index (FIC). The characterization of structural connectivity highlighted natural sinks and blankets zones as the main elements of disconnection in the catchment. The functional connectivity was evaluated for five distinct magnitude events, the results showed a higher influence of sediment availability and antecedent moisture conditions than the other structural factors. The FIC validated the theoretical indices in the study area and highlighted the importance of coupling thresholds between the numerous sediment sources in a known event.