DOCUMENTING ROCKFALLS IN YOSEMITE NATIONAL PARK WITH A NEW SPATIALLY ENABLED GEODATABASE AND INTERACTIVE WEB-BASED MAP

Yosemite National Park in northern California experiences frequent rock falls and other mass wasting events, posing hazard to the 4-5 million visitors annually. These events are recorded in an inventory database that extends back to 1857. The database includes detailed information about each event, including date, time, location, event type, volume, triggering conditions, infrastructure impacts, and injuries and fatalities. Three version of the database have been published, with the most recent released as a US Geological Survey Data Series report (Stock et al., 2013) containing event data through 2011. Since then, we have updated the database through 2020 and expanded it to include additional spatial data. The database now documents 1489 events, predominantly rock falls but also rock slides, debris flows, debris slides and other slope movement types. Earlier versions of the inventory database included only general rock fall locations in text format. We converted the old database to a spatially enabled geodatabase by reporting NAD83 UTM coordinates and NAVD88 elevations, along with inferred precision, for all database records. The precision of location data in the updated geodatabase varies from relatively low, when inferred from written descriptions of early events, to very high, when determined by lidar or structure-from-motion photogrammetry. Digital database records allow for GIS analyses of rock fall dependence on variables such as slope, aspect, elevation, rock type, and glacial extent. By coupling spatial and nonspatial attribute data in this new geodatabase, we created a robust single interface for interacting with rock fall data. Visualization capabilities within the web-based GIS application provide tools to symbolize rockfalls by attribute selection and configure maps with customized pop-up content that includes written narratives, select photos or videos if available, and links to additional sources of information such as scientific publications and media. The shift from a spreadsheet-based inventory database to a spatially enabled geodatabase and interactive web-based map increases access to the data, allows for new analysis of spatial factors influencing rock fall, and enhances the data viewing experience for scientific researchers and the general public alike.