Structural and sedimentological connectivity on a rilled hillslope

Understanding sediment transport dynamics remains a key challenge in geomorphology. While basin-scale connectivity has been widely studied, hillslope-scale processes remain less understood. Prior research has shown that sedimentological connectivity depends on the balance between sediment load and transport capacity. However, the specific influence of within-channel features, such as depressions and confluences, is not fully resolved. This gap motivated the need for detailed spatial and temporal analysis of sediment movement at smaller scales. No prior work had resolved how rill confluences and depressions specifically alter erosion and deposition patterns. The lack of high-resolution topographic data at the hillslope level has limited progress in this area. This paper addresses the uncertainty by using lidar-derived elevation models to track sediment redistribution over time. The study contributes a novel approach to quantifying connectivity at the rill network level.

The aim of this study was to investigate structural and sedimentological connectivity within a rill network on a hillslope. The researchers sought to determine how within-channel barriers and confluences influence sediment redistribution. They focused on the spatial and temporal dynamics of erosion and deposition over two years. The study aimed to quantify the role of rill confluences and depressions in shaping sediment patterns. It also aimed to compare observed patterns with a GIS-based index of connectivity. The researchers wanted to assess whether this index accurately captures the influence of structural connectivity. They also sought to identify the spatial extent of these influences. The study contributes a new method for analyzing hillslope-scale sediment dynamics.

The researchers used lidar-generated digital elevation models (DEMs) to track changes in topography over six periods. They calculated the DEM of Difference (DoD) to quantify erosion and deposition. The study area was a rilled hillslope in Loudon, Tennessee, USA. The time series of DEMs spanned from December 2014 to December 2016. They compared the observed sediment redistribution to a GIS-based index of connectivity (IC). The IC was used to assess structural connectivity features like confluences and depressions. The researchers examined how these features influenced sedimentological patterns over time. The study combined spatial analysis with temporal tracking to evaluate connectivity dynamics.

Later periods showed the highest erosion and net sediment loss, averaging 0.59 ± 17 m³. The study found a consistent spatial relationship between the IC and observed erosion/deposition patterns. Rill confluences were associated with increased erosion in both upslope and downslope areas. Depressions led to upslope deposition and downslope erosion. The IC captured structural connectivity but missed gravitational sidewall failures. These failures contributed to sediment detachment not reflected in the IC. The study confirmed that confluences and depressions significantly influence sediment redistribution. The observed patterns supported the role of structural connectivity in shaping sedimentological processes.

The study found that structural connectivity features like confluences and depressions strongly influence sedimentological patterns. The IC effectively captured these relationships but did not account for gravitational sidewall failures. The researchers propose that sediment redistribution is shaped by both structural and gravitational processes. The observed patterns suggest that confluences and depressions act as key points of sediment redistribution. The study supports the idea that connectivity is spatially consistent at the hillslope scale. The findings suggest that structural features can be used to predict sedimentological outcomes. The authors state that future work should integrate gravitational processes into connectivity models. The study contributes a new method for analyzing hillslope-scale sediment dynamics.