The erosion
model therefore only takes CAL-101 manufacturer non-channelized flow (rill and inter-rill processes) into consideration. As the USLE is widely used across the globe for assessing entire watershed sediment contributions (Erdogan et al., 2007, Pandey et al., 2007, Dabral et al., 2008, Ozcan et al., 2008, Hui et al., 2010 and Pradhan et al., 2012) its straightforward design should provide a platform for regional and global data comparisons. The USLE estimates mean annual soil loss in tons per acre per year (t/acre/yr) from a set of empirically constrained, unit-less variables of climatic, topographic, sedimentologic, and anthropogenic nature: equation(1) A=RKLSCP,A=RKLSCP,where A = mean annual soil loss in t/acre/yr, R = a rainfall erosivity factor, K = a soil erodibility factor, LS = a topography factor representing slope length and steepness, C = a cover-management factor (i.e. land-cover factor), and P = a MI-773 ic50 support-practice factor based on erosion-control measures. The study region is assigned a constant R-factor of 111 based on work by Wischmeier and Smith (1978). As the studied watershed is small (∼0.063 km2), the spatial distribution of the R-factor is assumed uniform as the effects of short-lived, high-energy rainfall events on sediment yield should be normalized against the long-term averaged mean over the 38-year
period of investigation. The P-factor, which lowers the soil-erosion estimate
(i.e. A-value in the USLE) by accounting for human soil-conservation measures, is non-applicable to the focus area. The foot path around Lily Pond, which represents the only actively maintained feature in the watershed, borders the pond directly, has no effect on slope erosion, L-NAME HCl and does not inhibit sediment flux to the pond. As neither slope-modification structures are visible and slope vegetation is not managed a P-factor value of 1 is used to reflect an absence of active soil-conservation measures since 1974 ( Wischmeier and Smith, 1978). The LS-factor, a combined metric that takes slope steepness and length into account, is calculated using a GIS-method devised by Moore and Burch, 1986a and Moore and Burch, 1986b. The LS-factor is based on a 3 m USGS DEM derived from the 1/9″ National Elevation Dataset. The USLE estimates contributions from rill and inter-rill erosion; erosion attributed to channel processes, which include erosion and deposition in gullies, must be accounted for and omitted from the model analysis. A necessary step to evaluate the LS-factor therefore includes the identification of gullies within the Lily Pond watershed and an establishment of a cap value in the flow accumulation model of the watershed to exclude erosional/depositional processes relating to channelized flow. One such gully is shown in Fig. 2C, which represents one of the largest of ∼10 encountered within watershed (Fig. 4C).