Watershed Boundary HUC6

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. 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.

每个流域均被视为水文单元（Hydrologic Unit, HU），并被分配水文单元代码（Hydrologic Unit Code, HUC）作为该区域的唯一标识符。HUC 2级、6级、8级、10级与12级代码依次对应美国境内的流域大区、次级大区、流域、次级流域、小流域与次级小流域。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则确定，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（United States Geological Survey, USGS）1:24000比例尺地形底图进行边界划定与地理配准。水文单元按照多级层级化流域系统进行嵌套式划定，并匹配对应的HUC代码，因此当从大尺度区域转向小尺度区域时，HUC代码的位数会以两位为增量递增。例如，代表最大尺度区域的HUC代码为2位，故称为HUC 2级代码；代表最小尺度区域的HUC代码为12位，故称为HUC 12级代码。

数据集概览
映射对象：美国境内由流域边界数据集（WBD）划定的流域。
地理覆盖范围：美国本土、阿拉斯加、夏威夷、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：Web Mercator（网络墨卡托投影）。
更新频率：年度更新。
可见比例尺：全比例尺均可显示，但美国地质调查局建议该数据集勿用于1:24000及更大比例尺的场景。
数据来源：美国地质调查局（USGS）。
数据时效：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。

图层应用场景
本图层适配ArcGIS全体系的可视化与分析工作。可将本图层与自有数据及ArcGIS全球生活地图集（ArcGIS Living Atlas of the World）中的其他图层在ArcGIS Online与ArcGIS Pro中进行融合，以制作功能强大的网页地图，该地图可单独使用，亦可嵌入故事地图或其他应用程序中。由于本图层隶属于ArcGIS全球生活地图集，因此可轻松添加至您的地图中：
1. 在ArcGIS Online中：依次选择「添加」→「浏览生活地图集图层」，弹出搜索窗口后，在搜索框中输入"Watershed Boundary Dataset"，浏览至目标图层并选中后，点击「添加至地图」即可完成添加。
2. 在ArcGIS Pro中：打开地图后，在「地图」选项卡中选择「添加数据」；在下拉菜单顶部选择「数据」，左侧将弹出「添加数据」对话框，按需展开「门户」选项并选择「生活地图集」；在搜索框中输入"Watershed Boundary Dataset"，浏览至目标图层后点击「确定」即可完成添加。

如有任何疑问，请在下方留言，我们将尽快为您回复。