Using Elevation Data to Produce an Updated Hydrography Dataset for the State of Pennsylvania

Ellen Fehrs


Department of Conservation and Natural Resources, Bureau of Geological Survey


The Pennsylvania Department of Conservation and Natural Resources (DCNR) Bureau of Geological Survey (BGS) has compiled a comprehensive workflow that will be used to generate hydrography data for the new elevation-derived Pennsylvania Hydrography Dataset (PAHD). This workflow relies primarily on geomorphon classification of (QL Level 2) lidar-derived elevation data as a means of identifying potential flowpath geometries which are subsequently winnowed to remove artifacts and other irrelevant features. The geomorphon areas that remain are further processed to create a vector flowpath network. Final steps in the workflow assign attributes, some from the NHD, others by running specific tools. The end goal is a scale-equivalent and dynamic hydrography dataset for the state of Pennsylvania, created using derivatives created from quality level (QL) 2 Light Detection and Ranging (Lidar) elevation data. For the purposes of this project, “scale-equivalent” is defined as horizontal accuracy to one meter and vertical accuracy to half a meter at a 1:2,400 scale with reference to the most current elevation data. This presentation briefly examines the major components of the most current methodology for producing flowpath geometries.