Estimating badland denudation with pin measurements and high resolution Digital Elevation Models derived from UAV image analysis

<p>The denudation of soil or soft rock surfaces by non-concentrated flow is mostly estimated by relating the&#160;sediment discharge observed at the outlet of a plot or natural micro-catchment to their respective surface&#160;areas. This approach generates an average denudation rate, but ignores spatial patterns of erosion and&#160;deposition. A well established approach to capture such spatial differences are pins, which deliver a highly&#160;precise point measurement of surface elevation change. Advances in the development of Unmanned Aerial&#160;Vehicles (UAVs) and imagine processing in the past decades offer an additional tool for mapping erosion&#160;and deposition at millimetre scale for continuous surfaces. In this study, pin and UAV-derived erosion data&#160;for a badland area in the Karoo rangelands, South Africa, are compared. The results show that typical annual&#160;erosion rates in the study area are lower than the differences between two DEMs generated a year apart.&#160;This illustrates that in situations where erosion rates are low, pins still offer the faster and more reliable&#160;results. For their extrapolation, on the other hand, UAV-derived DEMs provide suitable topographic data.</p>