Watershed Boundary HUC10

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），并被分配唯一标识符——水文单元代码（Hydrologic Unit Code, HUC）。在美国境内，2位HUC、6位HUC、8位HUC、10位HUC及12位HUC分别对应定义流域大区、亚大区、流域、亚流域、集水区与亚集水区。其边界依据水文与地形标准划定，勾勒出河流特定点位上游的陆地区域，完全遵循科学水文原则确定，不偏向任何行政边界、特殊项目、特定方案或机构。本流域边界数据集（Watershed Boundary Dataset, WBD）已完成数字化描边与地理配准，适配美国地质调查局（USGS）1:24000比例尺地形底图。水文单元采用多层级分级排水系统架构，配套对应HUC编码，因此从低尺度到高尺度时，HUC的位数以2位为增量递增。例如，级别最高的HUC为2位，即HUC 2级；级别最低的HUC为12位，即HUC 12级。

### 数据集摘要
**映射现象**：由流域边界数据集（Watershed Boundary Dataset, WBD）划定的美国境内集水区
**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
**投影方式**：Web墨卡托投影（Web Mercator）
**更新频率**：年度更新
**可见比例尺**：全比例尺下均可显示，但美国地质调查局建议该数据集不适用于1:24000或更大比例尺的应用场景
**数据来源**：美国地质调查局（United States Geological Survey, USGS）
**数据基准日期**：2025年1月7日
**数据获取日期**：2026年4月7日
**发布日期**：2026年4月11日

### 本图层应用方向
本图层适用于ArcGIS生态系统内的可视化与分析工作。可在ArcGIS Online与ArcGIS Pro中，将本图层与自有数据及ArcGIS世界生活地图集（ArcGIS Living Atlas of the World）的其他图层结合，制作可独立使用、或集成于故事地图及其他应用中的高性能网络地图。由于本图层属于ArcGIS世界生活地图集的一部分，添加至地图的操作十分便捷：
1. 在ArcGIS Online中：点击「添加」并选择「浏览生活地图集图层」，弹出搜索窗口后在搜索框输入"Watershed Boundary Dataset"，浏览找到目标图层后点击「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」，左侧弹出的「添加数据」对话框中，如有需要请展开「门户」选项并选择「生活地图集」，在搜索框输入"Watershed Boundary Dataset"，浏览找到目标图层后点击「确定」。

### 疑问反馈
如有任何关于本图层的疑问，请在下方留言，我们将尽快为您解答。