1992 digital surface model and orthomosaic of Malakoff Diggins State Historic Park, California

One of the largest hydraulic mines (1.6 km2) is located in Californias Sierra Nevada within the Humbug Creek watershed and Malakoff Diggins State Historic Park (MDSHP). MDSHPs denuded and dissected landscape is composed of weathered Eocene auriferous sediments susceptible to chronic rill and gully erosion whereas block failures and debris flows occur in more cohesive terrain. This data release includes a 1992 digital surface model (DSM), 1992 orthophoto mosaic, masked orthophoto of the study area, 1992 ground cover classification, and 1992 pruned DSM with the vegetation bias removed. Stereo-photogrammetry was used to create a 1992 digital surface model (DSM) and orthophoto mosaic from archived 1992 aerial photographs. These datasets can be used to map vegetation and topographic change and to quantify volumetric differences and estimate erosion rates by co-referencing and differencing the 1992 DSM from more recent bare earth digital elevation models. Any direct volumetric comparison using these datasets should consider the horizontal and vertical minimum thresholds of significance as well as vegetation bias. The original DSM was derived using stereo photogrammetry and includes all vegetation components. To facilitate topographic change analysis a pruned DSM was created. The vegetation bias was removed from the pruned DSM using a ground cover classification. It is recommended that the pruned DSM be used for any topographic or volumetric change analysis.