Watershed Boundary HUC12

Each drainage area is considered a Hydrologic Unit (HU) and is given a Hydrologic Unit Code (HUC) which serves as the unique identifier for the area. HUC 2s, 6s, 8s, 10s, & 12s, define the drainage Regions, Subregions, Basins, Subbasins, Watersheds and Subwatersheds, respectively, across the United States. Their boundaries are defined by hydrologic and topographic criteria that delineate an area of land upstream from a specific point on a river and are determined solely upon science based hydrologic principles, not favoring any administrative boundaries, special projects, or a particular program or agency. The Watershed Boundary Dataset is delineated and georeferenced to the USGS 1:24,000 scale topographic basemap. Hydrologic Units are delineated to nest in a multi-level, hierarchical drainage system with corresponding HUCs, so that as you move from small scale to large scale the HUC digits increase in increments of two. For example, the very largest HUCs have 2 digits, and thus are referred to as HUC 2s, and the very smallest HUCs have 12 digits, and thus are referred to as HUC 12s. Dataset Summary Phenomenon Mapped: Watersheds in the United States, as delineated by the Watershed Boundary Dataset (WBD) Geographic Extent: Contiguous United States, Alaska, Hawaii, Puerto Rico, Guam, US Virgin Islands, Northern Marianas Islands and American Samoa Projection: Web Mercator Update Frequency: Annual Visible Scale: Visible at all scales, however USGS recommends this dataset should not be used for scales of 1:24,000 or larger. Source: United States Geological Survey (WBD) Data Vintage: January 7, 2025 Data Accessed: April 7, 2026 Publication Date: April 11, 2026 What can you do with this layer? This layer is suitable for both visualization and analysis acrossthe ArcGIS system. This layer can be combined with your data and other layers from the ArcGIS Living Atlas of the World in ArcGIS Online and ArcGIS Pro to create powerful web maps that can be used alone or in a story map or other application. Read the Earth Day Celebration at Machicomoco blog for an example of how to use the WBD layers. Because this layer is part of the ArcGIS Living Atlas of the World it is easy to add to your map: In ArcGIS Online, you can add this layer to a map by selecting Add then Browse Living Atlas Layers. A window will open. Type "Watershed Boundary Dataset" in the search box and browse to the layer. Select the layer then click Add to Map. In ArcGIS Pro, open a map and select Add Data from the Map Tab. Select Data at the top of the drop down menu. The Add Data dialog box will open on the left side of the box, expand Portal if necessary, then select Living Atlas. Type "Watershed Boundary Dataset" in the search box, browse to the layer then click OK. Questions? Please leave a comment below if you have a question about this layer, and we will get back to you as soon as possible.每个汇水区均被视为水文单元（Hydrologic Unit, HU），并分配有水文单元编码（Hydrologic Unit Code, HUC）作为该区域的唯一标识符。HUC 2级、6级、8级、10级及12级编码依次对应美国全境的汇水大区、次级汇水区、流域、子流域、水体集水区与次级小流域。其边界依据水文与地形学标准划定，用于勾勒河流特定点位上游的陆地区域，且完全基于科学水文原理确定，不偏向任何行政边界、专项工程、特定项目或机构。 本流域边界数据集（Watershed Boundary Dataset, WBD）按照美国地质调查局1:24000比例尺地形底图进行划定与地理配准。水文单元按照多级层级化汇水系统进行嵌套划定，并匹配对应的HUC编码，因此当从较小比例尺（大范围）切换至较大比例尺（小范围）时，HUC编码的位数以2位为增量递增。例如，级别最高的HUC编码为2位，即HUC 2级；级别最低的HUC编码为12位，即HUC 12级。 ## 数据集概况 制图对象：由流域边界数据集（WBD）划定的美国境内流域 地理覆盖范围：美国本土、阿拉斯加州、夏威夷州、波多黎各、关岛、美属维尔京群岛、北马里亚纳群岛和美属萨摩亚 投影坐标系：Web墨卡托投影 更新频率：每年一次 可见比例尺：全比例尺下均可显示，但美国地质调查局建议本数据集勿用于1:24000及更大比例尺的应用场景 数据来源：美国地质调查局（WBD） 数据版本时间：2025年1月7日 数据获取时间：2026年4月7日 发布日期：2026年4月11日 ## 该图层可实现的应用场景 本图层适用于ArcGIS生态系统内的可视化与分析工作。您可将本图层与自有数据及ArcGIS在线世界活图集（ArcGIS Living Atlas of the World）中的其他图层在ArcGIS Online或ArcGIS Pro中进行整合，以制作功能强大的网络地图，该地图可单独使用，也可嵌入故事地图或其他应用程序中。可参阅《Machicomoco地球日庆祝活动》博客文章，了解WBD图层的使用示例。 由于本图层属于ArcGIS在线世界活图集的一部分，因此可轻松添加至您的地图中： 1. 在ArcGIS Online中，依次选择「添加」→「浏览活图集图层」，此时将弹出窗口；在搜索框中输入“流域边界数据集”，浏览并找到目标图层；选中该图层后点击「添加至地图」即可。 2. 在ArcGIS Pro中，打开地图后选择「地图」选项卡中的「添加数据」；在下拉菜单顶部选择「数据」，此时左侧将弹出「添加数据」对话框；若需展开门户（Portal）目录，则点击展开，随后选择「活图集」；在搜索框中输入“流域边界数据集”，浏览并找到目标图层后点击「确定」即可。 如有疑问？若您对本图层有任何问题，请在下方留言，我们将尽快回复您。