Montgomery County Watersheds - Minor

This layers shows major watershed boundaries in Montgomery County, Pennsylvania. This USGS map layer displays the National Watershed Boundary Dataset (WBD) for HUC12 boundaries. The intent of defining hydrologic units (HU) for the WBD is to establish a base-line drainage boundary framework, accounting for all land and surface areas. The WBD is a comprehensive aggregated collection of HU data consistent with the national criteria for delineation and resolution. Each HU is identified by a unique hydrologic unit code (HUC).本图层展示了宾夕法尼亚州蒙哥马利县的主要流域边界。该美国地质调查局（United States Geological Survey，简称USGS）地图图层展示了适用于HUC12级边界的国家流域边界数据集（National Watershed Boundary Dataset，简称WBD）。为WBD定义水文单元（hydrologic units，简称HU）的核心目标，是构建一套基准排水边界框架，覆盖全部陆地与地表区域。WBD是一套全面整合的水文单元数据集合，符合国家统一的划定标准与分辨率要求。每个水文单元均通过唯一的水文单元代码（hydrologic unit code，简称HUC）进行标识。