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.

本数据集发布内容包含圣劳伦斯五大湖区域水生间隙分析项目（Great Lakes Regional Aquatic Gap Analysis Project, GLGap）海岸水空间框架（Coastal Hydrospatial Framework）下各级空间单元的地理参考边界，其覆盖的空间尺度范围从本地90米栅格单元延伸至整个圣劳伦斯五大湖系统，空间覆盖范围则从岸线直至远海最深水域。
美国地质调查局（U.S. Geological Survey）与美国鱼类及野生动物管理局（U.S. Fish and Wildlife Service）合作构建了覆盖圣劳伦斯五大湖全域的通用空间区域框架。
最精细的空间单元（90米栅格）经聚合可形成粒度更粗、范围更广的空间单元。六级空间尺度下，精细单元嵌套于粗粒度单元之中，六个尺度分别为：本地栅格单元（Local Cells）、水生栖息地单元（Aquatic Habitat Areas）、海岸或敞水区（Coastal or Openwater Zones）、湖泊水体单元（Aquatic Lake Units）、湖盆（Basins）以及全域系统（System）。
每个本地栅格单元的地理参考位置可作为空间点位，用于关联对应区域的生物与非生物属性。
各级空间单元均关联若干基础属性。最精细的空间单元以边长90米的正方形栅格网格形式呈现，每个栅格均自带其质心的地理坐标信息。
本数据集依托一套规则定义所有空间单元的边界，该规则以五大湖岸线与四项描述水生栖息地物理状态的变量为基础，四项变量分别为：有效风区（effective fetch）、至最近大型河口的距离、沉水植被分布情况以及水深。
本数据集提供了一套客观、标准化、多尺度的分级空间框架，依托统一的空间组分体系，可在分级体系内部及跨空间尺度开展分析与关联研究，进而生成五大湖区域内多种空间区域分类方案，以解决各类相关问题。
该框架基于明确的单元定义规则构建，可扩展应用于海洋岸线与其他大型水体的空间划分工作。