Effects of Soil Conservation Practices on Sediment Yield from Forest Road Ditches in Northern Iran

Abstract

<jats:p>The fine-textured soil in forest road ditches is very susceptible to water erosion especially in rainy seasons in Hyrcanian forest. This study examined the yield of ditch segment-scale sediment after releasing two flow rates of 5 l s-1 and 10 l s-1 in segments treated by riprap (RR), grass cover by Festuca arundinacea L. (GC), compacted cotton geotextile (CG) and wooden wattle by local slash (WW). Sediment sampling from the runoff was carried out at the end of each segment every minute. Runoff flow velocity in different treatments was measured using an electromagnetic flow meter. Sediment concentration and runoff velocity in treatments of RR, GC, CG, WW was significantly lower than that of the control plot (Ctl). Increasing flow rate from 5 l s-1 to 10 l s-1 caused no significant change in sediment concentration (except for Ctl and RR) and runoff velocity (except for Ctl and CG), which means that some water might have penetrated into treated soil by RR, GC and WW and this is not acceptable in forest road maintenance practices. Sediment yield from RR (0.36 g l-1) and Ctl (0.50 g l-1) under the flow rate of 10 l s-1 was significantly higher than that of 5 l s-1 with values of 0.21 g l-1 and 0.38 g l-1, respectively. Minimum amount of sediment concentration was observed for CG (0.20 g l-1) with compacted ditch bed. Moreover, runoff velocity in CG and Ctl under the flow rate of 10 l s-1 was significantly higher than that of 5 l s-1. For a forest road with dimension 30×50 cm, slope of 5%, and clay soil with porosity of 57%, treatments of compacted CG can be used in ditch with low flow rates (5 l s-1) and high flow rate (10 l s-1) because of their high efficiency in reducing sediment yield.</jats:p>

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.…”

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

“…Strategies such as adopting low-impact road construction techniques, implementing erosion control measures, and minimizing tra c volume and speed can help reduce the negative impacts of road construction and maintenance on land degradation in forest lands.During the early years of construction, forest roads experience the highest levels of runoff production and soil erosion due to the destruction of vegetation, soil compaction, and disturbance of geomorphological connectivity(Arnáez et al 2004;Mahdavi 2012;Safari et al 2016). However, over time, as vegetation and the forest ecosystem recover, the impact on the roadside environment gradually diminishes, leading to more stable conditions for vegetation and soil(Khandouzi et al 2020). Therefore, protecting the edge of forest roads during the early years of construction is critical.…”