Hydrospatial Framework for the Laurentian Great Lakes

This data release provides the georeferenced boundaries that delimit each spatial unit of the Great Lakes Regional Aquatic Gap Analysis Project (GLGap) Coastal Hydrospatial Framework at each spatial scale from the local 90m cell to the entire Laurentian Great Lakes system and from the shoreline to the deepest offshore waters. The U.S. Geological Survey and the U.S. Fish and Wildlife Service collaborated to design a universal framework of spatial areas that encompass all space of the Laurentian Great Lakes proper. Agglomeration of the finest units (90m cells) form coarser, broader scale units. Finer units are nested within the coarser units at six spatial scales, labeled as Local Cells, Aquatic Habitat Areas, Coastal or Openwater Zones, Aquatic Lake Units, Basins, and System. The georeferenced location of each local cell provides a point in space where biotic and/or abotic characteristics of that area may be attributed. A few basic attributes are associated with units at each spatial scale. The finest spatial units are represented as a raster grid of squares 90m long with inherent geographic location of each centroid. A set of rules uses the Great Lakes shoreline and four variables that describe physical conditions of aquatic habitat (effective fetch, distance to nearest large river mouth, presence of submerged aquatic vegetation, and water depth) to define each spatial unit boundary. These data provide an objective, standardized, multi-scale, hierarchical framework from which multiple classifications of spatial areas within the Great Lakes may be generated to address a multitude of problems, based on a common set of spatial components that can be examined and related within and across spatial scale within the hierarchy. This framework is built upon clear, unit-defining rules that are extendable to marine coasts and other large water bodies.