Effects of Human-Induced Land Use Changes on Hydrosedimentological Connectivity in a Small Catchment

Hydrosedimentological connectivity refers to the transfer of water and sediment between landscape compartments, originating from any possible source and reaching a specific control point within a system where water serves as the transport vector. Assessing connectivity is a crucial step in comprehending the system’s behavior, enabling the prediction of its response to precipitation events and land-use changes that may arise within the catchment. Changes in land use within a catchment have a significant effect on connectivity, thereby affecting water and sediment dynamics. In this study, an analysis was conducted to examine the influence of human-induced land use changes on hydrosedimentological connectivity in a small catchment located in Campos de Cima da Serra, Rio Grande do Sul. The IHC (Index of Hydrosedimentological Connectivity) was applied to five precipitation events with varying hydrological characteristics, including rainfall magnitude, available sediments, and antecedent soil moisture. Four different scenarios were considered, maintaining the land use classes of the region but modifying their coverage. The analysis of these scenarios revealed the influence of land use on the catchment, leading to variations in the pattern of hydrosedimentological connectivity. The highest IHC values were observed in areas characterized by exposed soil (agricultural preparation) and agricultural activities. Conversely, the lowest connectivity points in the catchment were found in regions with native forest and Pinnus forest. These areas possess a significant potential for sediment retention due to the presence of plant litter. Additionally, the analysis of different precipitation events demonstrated that antecedent events and soil moisture conditions play a crucial role in estimating the hydrosedimentological connectivity of the catchment. These factors were shown to be determinants in understanding how connectivity varies over time. The findings highlight the influence of different land use scenarios on connectivity patterns and provide insights into the potential for sediment retention in specific landscape elements. Additionally, the study demonstrates the significance of considering antecedent events and soil moisture conditions when evaluating hydrosedimentological connectivity within a catchment.