Addressing the challenge of sediment connectivity analysis in areas with low topodiversity: proposing new insights

Since sediments in water bodies adsorb and retain contaminants, they can cause serious impacts on public health. Although sediment dynamics is a long-established concept and is increasingly adopted as a practical paradigm in environmental process studies, significant challenges remain for its application in topographically homogeneous areas. This study presents a novel framework for sediment connectivity mapping in low-roughness regions characterized by distinctive watershed configurations, where geo-environmental attributes play a more prominent role than topography in governing erosion and sedimentation cycles at the watershed scale. The conventional roughness-based connectivity approach (IC_r) was compared against three alternative scenarios incorporating: (1) lithological erodibility (IC_l), (2) vegetation status (IC_v), and (3) an ensemble of multiple factors (IC_e). The validity of these proposed methods was evaluated using field sediment connectivity data from multiple sites, employing both graphical and numerical assessments. Results indicate that the generated sediment connectivity maps are broadly consistent, yet exhibit appreciable spatial differences in sediment dynamics patterns. Correlation analyses between field data and the four map products revealed that IC_e yielded the strongest performance (R² = 0.831), followed by IC_v (R² = 0.725) and IC_l (R² = 0.686), while the roughness-based formula (IC_r) ranked lowest (R² = 0.548). Notably, our findings demonstrate that the ensemble integration of geo-environmental and topographical factors does not necessarily enhance map accuracy, underscoring the need for a context-sensitive configuration in sediment connectivity simulation to better represent complex watershed conditions. This study further provides practical guidance for geoscientists seeking to simulate spatial sediment connectivity in low-roughness, low-vegetation landscapes, thereby supporting the design of sediment control measures and the improvement of environmental management strategies.