Optimizing Management Practices to Reduce Sediment Connectivity between Forest Roads and Streams in a Mountainous Watershed

Abstract

Forest roads often increase runoff and sediment loss, thus greatly impacting hydrological processes in mountainous watersheds. While there has been previous investigation on best management practices (BMPs) to reduce soil erosion from forest roads, few studies have attempted to optimize BMPs based on how much they can decrease sediment connectivity between forest roads and streams. To close this gap in knowledge, we analyzed the spatial relationship between forest roads and streams, presented the spatial distribution of sediment connectivity by integrating the forest roads into the calculation of the index of connectivity (IC), determined how sediment connectivity would respond to additional BMPs through simulating scenarios, and used these data to optimize the BMPs so they would intercept the greatest sediment loads. We found that forest roads and streams in the Xiangchagou watershed in the Dabie Mountain area of China tend to occur within 180 m of each other; however, within the same buffer zones, streams are more often accompanied by forest roads. IC was greatest near road–stream crossings but smaller near streams and forest roads, and it tended to decrease as the buffer distance increased. Furthermore, we found that sediment connectivity was decreased through running a variety of scenarios that used sediment basin and riparian buffers as BMPs between forest roads and streams. Specifically, within this watershed, riparian buffers should be 64 m wide, and there should be 30 sediment basins with a minimum upslope drainage area of 2 ha. At these quantities, the BMPs in this watershed would significantly affect sediment connectivity. By contrast, beyond these thresholds, increasing the width of riparian buffers or the number of sediment basins does not lead to meaningful sediment reductions. In this way, we were able to use the mean change point method to determine the optimal sediment basin quantity (30 with corresponding minimum upslope drainage area of 2 ha) and the optimal riparian buffer width (64 m) for the Xiangchagou watershed. While these results are a first approximation in a novel research area, they can guide forest managers and stakeholders to design and optimize BMPs that control the delivery of eroded sediments associated with forest roads.

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

“…and physical and chemical restoration (consolidation, soil washing, etc.) (Higgs, 2005; Zhao, Wang, et al, 2022). The complexity of ecological restoration technology is noteworthy as it requires the integration of factors such as vegetation, soil characteristics, and topography.…”

“…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.…”

A hot-spot analysis of forest roads based on soil erosion and sediment in Zagros forest lands, Iran

“…Road width is an important factor that can signi cantly affect soil erosion and road destruction (Cao, Wang, et al 2021;Zhao et al 2022). Narrow roads can cause concentrated ow and erosion, leading to gully formation, while wide roads can increase the surface area of the road and reduce the velocity of water, which can reduce soil erosion (Amiri et al 2019; Wang et al 2022).…”

“…It can also enter waterways and rivers and cause sedimentation in the reservoirs of dams, wetlands, lakes, seas, and even change the landscape morphology. Additionally, road construction is a factor in providing the basis for other erosion types (Prendes et al 2019; Zhao et al 2022). The amount of environmental destruction and the area of forests and pastures resulting from road construction depend on various factors such as the type of road, the topography of the area, the sensitivity of the soils, and the geological formations of the road route (Brown et al 2015;Youse et al 2016).…”

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

“…Road erosion encompasses various erosion processes occurring within the road prism, involving sediment detachment and deposition on cut slopes, road surfaces, side ditches, and fill slopes [15]. Substantial research efforts have been devoted to comprehending the mechanisms of sediment production through forest road erosion, the processes and mechanisms of sediment transport, and management measures for erosion control aimed at protecting soil resources and mitigating forest road erosion [16,17].…”