Modeling and mapping soil resistance to penetration and rutting using LiDAR-derived digital elevation data

Soil resistances to penetration were probed with a hand-held soil cone penetrometer across ridge-to-depression transects for two contrasting study areas in Alberta, Canada: one in the foothills west of Calgary, and one in the boreal plain north of Peace River. The resulting cone index values (CI) were related to plot-measured values for soil moisture, density, texture, organic matter content, soil depth, elevation, slope, and a cartographic depth-to-water index (DTW) by way of multiple regression analysis. Elevation, slope, DTW, and the associated flow accumulation pattern were all derived from a light detection and ranging (LiDAR)-generated bare ground digital elevation model (DEM), at 1 m (3 ft) resolution. The field-determined CI values conformed to a previous formulation that related CI to soil texture, density, and water-filled pore space. In terms of topographic position, CI increased with increasing DTW, in parallel with decreasing soil moisture content and increasing soil density. The resulting best-fitted regression between CI, log(10)(DTW), and elevation (or study area) was used to map CI and expected all-terrain recreational vehicle-specific rutting depths across the landscape. The maps so generated were in general agreement with the results of a 40 km (25 mi) long soil disturbance survey along a recreational vehicle trail section within the foothill area.