Accuracy assessment of LiDAR‐derived DEMs of bedrock river channels: Holtwood Gorge, Susquehanna River

Abstract

We evaluate the accuracy of 1 m, LiDAR‐derived DEMs of an exposed bedrock channel, and use these high‐resolution terrain models to calculate erosional fluxes between four levels of strath terraces dated previously with 10Be. Recent investigations into the timing, rates, and processes by which rivers incise their bedrock channels have greatly enhanced our understanding of landscape evolution. However, measuring channel geometries in 3 dimensions is difficult; thus, volumes of bedrock eroded during incision events are rarely considered. Although our analysis successfully demonstrates the proportionality between incision rates and erosional fluxes for terraces high above the channel floor in this gorge, unusually high river flows on the date of acquisition inundated lower bedrock surfaces, preventing accurate volume estimates. To ensure optimal low‐flow LiDAR coverage for fluvial environments, we discuss methods to improve the scheduling of data acquisition by using archived discharge records and predictive models based on real‐time data.