Division of Science & Resource Management, Glacier National Park
Funded by the Glacier National Park Conservancy and working in cooperation with the Montana State Library, Glacier National Park personnel contributed local knowledge to improve Montana’s National Hydrography Dataset (NHD). The previous NHD was based on 1960s-vintage topographic mapping. The update process relied heavily on a time series of high-resolution orthophoto datasets that include 2005-2013 true color and color infrared National Agriculture Image Program (NAIP) images at 1-m resolution, 2009 Department of Homeland Security Border imagery at 6-inch resolution, and Esri’s World imagery at 1-m or better resolution. The imagery provided the information needed to map hydrographic features that have changed over time. The average level of many park water bodies has dropped, while ice masses have retreated substantially. The time series of images showed high/low water levels and residual snowpack/ice areas to allow accurate delineation of current extents. The edits made to the NHD make a major leap forward in depicting current ground conditions while also capturing the effects of climate and other landscape disturbances (i.e., floods, avalanche, fire) that have changed the extent and location of hydrographic features. The technical cooperation and workflow established through this project serves as a model for other Federal, State, and local organizations engaged in hydrography stewardship efforts.
Updated NHD features in the Two Medicine HUC (hydrologic unit code). The orange lines represent the “artificial path” needed to connect the lakes to the NHD stream network. The white polygon represents a revised ice mass boundary.