Response of Sediment Connectivity to Altered Convergence Processes Induced by Forest Roads in Mountainous Watershed

Abstract

Forest roads significantly affect sediment connectivity in mountainous catchments by contributing to the production of and disturbing the confluence of sediment-loaded runoff. This study considered forest roads as pathways and sinks of sediment-loaded runoff to understand the effects of forest roads on the confluence characteristics and sediment connectivity in mountainous a catchment using a scenario simulation. In order to determine the contribution and spatial relationship between sediment connectivity and influencing factors, this study utilized buffer analysis, an extremely randomized tree model, and multiscale geographically weighted regression. The results show that the presence of forest roads significantly changes the transport process and connectivity of runoff and sediment in the mountainous catchment. Specifically, flow length increases, but flow accumulation, upslope contributing area, and topographic index decrease with increasing distance from roads and streams. Meanwhile, the effects of roads on convergence characteristics and sediment connectivity are mainly manifested within a certain threshold that varies with different confluence characteristics. Moreover, sediment connectivity increases when considering roads as pathways and sinks of sediment-loaded runoff, especially on the upper hillslopes intercepted by roads and at the road–stream crossings. In addition, the closer the distance to the roads, the greater the impact of road on the confluence characteristics and sediment connectivity. Change in flow length is the most important factor affecting the sediment connectivity among all of the other convergence, terrain, and spatial distance characteristics. The longer the flow length, the lower the sediment connectivity. In conclusion, this study demonstrates that the altered confluence processes by roads increases the possibility that sediment-loaded runoff will be transported to the catchment outlet, which is of significance for the proper management of forest roads in mountainous catchments.

A Review of the Sediment Production and Transport Processes of Forest Road Erosion

“…This understanding allows for the identification of key road segments as sediment sources and priority areas for soil and water conservation, facilitating the prevention and control of sediment transport from roads to streams and the maintenance of watershed ecological security [24]. Therefore, comprehending the mechanisms of sediment connectivity between roads and streams is pivotal for mitigating the off-site effects of road erosion [90,91].…”

Elucidating the response mechanisms of hydrological and sediment connectivity to the river network structure, vegetation, and topographic features in the Jinghe River Basin

“…According to Jing et al (2022), the influences of river and road network structure on sediment connectivity were found to be significant and effective. Zhao et al (2022) considered the response variables such as river network structure and topography, revealing that changes in flow length significantly affected sediment connectivity, thereby offering an advantage in identifying sediment transport paths. The spatial dynamics of connectivity under the context of river network alteration can deepen our comprehension of watersheds (Wu et al, 2023).…”

Soil erosion associated with roads—A global review and statistical analysis

“…Recognizing the detrimental consequences, scholars have devoted considerable effort to studying road erosion. Research in this field has predominantly focused on erosion characteristics such as soil stripping and deposition on road surfaces (Khandouzi et al, 2020; Safari et al, 2016), sediment transport from roads to streams (Hearn, 2016; Saad et al, 2021; Zhao, Jing, et al, 2022), as well as erosion modeling and management strategies (Liu, Wang, et al, 2016; Ramos‐Scharrón, 2021; Zhao, Wang, et al, 2022). These studies collectively provide a comprehensive understanding of road erosion, offering valuable theoretical and practical insights.…”