A Geospatial Analysis of +50,000 Citizen-Science collected GPS Flood Extents and Street-Level Hydrodynamic Model Forecasts during the 2017 King Tide in Hampton Roads, VA

`Catch the King' Tide was the world's largest simultaneous citizen-science GPS data collection effort. Heavily promoted by the local news media, citizen engagement during the inundation event was high, resulting in an average of 572 GPS-reported high water marks per minute during hour surrounding the king tide's peak. Time-stamped GPS flood extent measurements and photographic evidence were reported via the `Sea Level Rise' Mobile App, coinciding with king tide, observed at 9:32 am (EST) on November 5, 2017, in Hampton Roads, VA. Over 700 volunteers mapped the king tide's maximum flood extent to validate and improve predictive models and future forecasting of increasingly pervasive nuisance flooding. 59,006 high water marks and 1200+ geotagged pictures of inundation were captured using the `Sea Level Rise' mobile app to trace the shape of the floodwaters using GPS location services.