Terrestrial Laser Scanning Data from Malakoff Diggins State Historic Park, Nevada County, California, 2014-17.

High-resolution, terrestrial laser scanning (TLS), was used to quantify the volume of sediment eroded from outcrops at Malakoff Diggins State Historic Park, located about 17 kilometers (km) northeast of Grass Valley, California. TLS was used to create centimeter-scale, three-dimensional (3-D) maps of the complex outcrop surfaces, which could not be mapped non-destructively or in sufficient detail with traditional surveying techniques. To develop a comprehensive sediment budget for the Malakoff Diggins mine pit that will help identify sources of sediment and metals within the pit that comprise the suspended sediment discharged from the pit into Humbug Creek, the USGS used TLS technology to quantify the eroded volumes and erosion rates of sedimentary units exposed in the pit walls. Eroded volumes from nineteen sedimentary units at four study sites located throughout the pit were calculated for the period December 2014 to August 2017. (Note that the monitoring sites were numbered 1, 2, 4, and 5.) Each survey at all four study sites was comprised of multiple lidar scans collected from different vantages that were combined into a composite 3-D point cloud. At all four study sites, the sequential surveys were co-registered or 'aligned' into a common and site-specific reference frame so that volumetric comparisons between surveys could be made. At each study site, sedimentary units were differentiated based on grain size, color, compaction, cementation, and slope angle. The various sedimentary units were mapped on the lidar point clouds and individually isolated for volumetric change analysis. The volumetric differences between surveys quantify the erosional and/or depositional volume change of each sedimentary unit.