1992 digital surface model Malakoff Diggins State Historic Park, California

One of the largest hydraulic mines (1.6 km2) is located in California’s Sierra Nevada within the Humbug Creek watershed and Malakoff Diggins State Historic Park (MDSHP). MDSHP’s 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 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.全球范围内规模较大的水力采矿场之一，占地面积达1.6平方千米，坐落于加利福尼亚州内华达山脉的洪堡溪流域以及马拉科夫迪金斯州立历史公园（Malakoff Diggins State Historic Park，简称MDSHP）境内。该公园内剥蚀破碎的地表由风化的始新世含金沉积物构成，易遭受持续性细沟与沟谷侵蚀；而在黏结性更强的地形区域，则易发生块体崩塌与泥石流灾害。本次数据发布包含1992年数字地表模型（Digital Surface Model，DSM）、1992年正射影像镶嵌图、研究区掩膜正射影像、1992年地表覆盖分类数据，以及已去除植被偏差的1992年修剪版数字地表模型。研究团队利用立体摄影测量技术，基于存档航空影像制作了1992年数字地表模型与正射影像镶嵌图。通过将1992年数字地表模型与最新的裸土数字高程模型（Digital Elevation Model，DEM）进行配准并差分，可利用本次发布的数据集绘制植被与地形变化图、量化体积差异并估算侵蚀速率。任何基于本数据集开展的直接体积对比分析，均需考虑水平与垂直方向的显著性最小阈值，同时也应纳入植被偏差的影响。原始数字地表模型通过立体摄影测量技术生成，包含所有植被覆盖的高程信息。为便于开展地形变化分析，研究人员制作了修剪版数字地表模型，并基于地表覆盖分类数据剔除了该模型中的植被偏差。建议在开展地形或体积变化分析时，优先使用该修剪版数字地表模型。