Relative Importance of Dust, Splash, and Sheet/Rill Transport Processes on Off-Highway Vehicle Trails in the Ouachita Mountains

Abstract:

Sheet/rill erosion, dust displacement, and vehicle induced splash are the primary sediment transport processes on off-highway vehicle (OHV) trails in the Ouachita Mountains of the central United States. The relative importance of these three processes is assessed by comparing the area affected and the sediment connectivity of each process to affected streams using field data from the Wolf Pen Gap Trail Complex. The occurrence and areal extent of erosion processes were assessed using systematic transect measurements, feature inventories, and visual observation over representative trail segments.

<span"> Sheet/rill erosion affects the entire denunded surface of the trail system, an area of 2,820 m² km^-1 of trail. Distinct erosion features created by sheet/rill erosion occur 16.3 times per km. Dust transport extends a mean travel distance of 3.7 m off-trail. Dust transport affects both the entire trail area and an additional 6,640 m² km^-1 of off-trail area. In contrast, splash transport was restricted to trail dips, and extends 1.6 m off-trail. Splash transport affects 60 m² km^-1of off-trail area.

<span">The impact of trail erosion increases where sediment sources are connected to drainageways. Of 480 sheet/rill erosion features rated, 69.4% had high to very high connectivity to channels. All sampled dips were directly connected to drainage ways. Dust transport affected 99% of dips on one trail side and 90% on both sides. About 80% of the dips had splash transport on one trail side and 42% on both sides.

<span">Sheet/rill, dust, and splash transport processes are all important in the Trail Complex, but for different reasons. Sheet/rill erosion affects the entire trail surface, is well connected to area drainageways, but only occurs after rainfall. Dust transport affects the largest area and occurs most often throughout the year, but the sediment is deposited diffusely, and the ratio delivered to the drainage network is relatively low. Splash affects the smallest area and is limited to short periods following rainfall, but is highly connected to the drainage network and the sediment delivery ratio is relatively high.