Comparing hydrologic impacts on recreational trails to remotely sensed data

Trails systems have impacts on the surrounding hydrology and vegetation health. Trails not only remove and disturb vegetation but also compact the soil. This may result in water pooling and flowing along the trail which may result in changes to the watershed. This paper explores whether readily available remotely sensed data can be used to detect hydrologic and geomorphic changes on the ground. We collected data about areas of deposition and paths of transportation along the trails. Two 3-m resolution aerial images were acquired from Planet Labs and Normalized Difference Vegetation Index (NDVI), and Soil Adjusted Vegetation Index (SAVI) band combinations were calculated. We also acquired the most recent lidar data from the United States Geological Survey (USGS). This lidar data was used to construct a Digital Elevation Model (DEM) of the trail system followed by a flow accumulation, slope, and curvature raster. Statistical analysis was used to determine a relationship between the intensity of on the ground observa- tions of hydrologic change and the remote sensing raster using box plots and nominal logistic regression. Results varied depending on the raster layer evaluated and the inclusion of a buffer around the deposition areas and transportation paths.