Influence of storm characteristics on soil erosion and storm runoff
Unpaved forest roads can be major sources of sediment from forested watersheds. Storm runoff from forest roads are a concern due to their potential delivery of sediments and nutrients to stream systems resulting in degraded water quality. The volume and sediment concentrations of stormwater runoff emanating from forest roads can be greatly influenced by storm characteristics, road management practices, and/or the interaction of management practices and subsequent storm events. In an attempt to gain a better understanding of storm runoff characteristics and erosion losses from forest roads, an investigation was initiated to quantify the influence of storm characteristics on runoff concentrations, runoff volumes, and soil erosion using data from three field experiments in Alabama and Georgia. Collected field data included a total of 54, 156, and 24 observations for field experiments 1(Appalachian Highlands of NW Alabama), 2 (Coastal Plain of SE Alabama), and 3 (Blue Ridge Mountains of NE Georgia), respectively. Mean event precipitation for the field experiments ranged from 33.5 to 62.5 mm and average storm intensities were 8.7, 3.8, and 3.5 mm hr-1 for field experiments 1, 2, and 3, respectively. Storm characteristics explained as much as 40 percent of the variability in runoff concentrations and soil erosion losses from the field experiments. Total precipitation, average rainfall intensity, and maximum 30-minute rainfall intensity were detected as the most influential storm characteristics in determining soil erosion based on the field experimental data from Coastal Plain and Appalachian forest roads.