HIFLD OPEN Flowline - Small Scale

The USGS National Hydrography Dataset (NHD) service from The National Map is a comprehensive set of digital spatial data that encodes information about naturally occurring and constructed bodies of surface water (lakes, ponds, and reservoirs), paths through which water flows (canals, ditches, streams, and rivers), and related entities such as point features (springs, wells, stream gages, and dams). The information encoded about these features includes classification and other characteristics, delineation, geographic name, position and related measures, a "reach code" through which other information can be related to the NHD, and the direction of water flow. The network of reach codes delineating water and transported material flow allows users to trace movement in upstream and downstream directions. In addition to this geographic information, the dataset contains metadata that supports the exchange of future updates and improvements to the data. The NHD is available nationwide in two seamless datasets, one based on 1:24,000 (or larger) scale and referred to as high resolution NHD, and the other based on 1:100,000 scale and referred to as medium resolution NHD. The NHD from The National Map supports many applications, such as making maps, geocoding observations, flow modeling, data maintenance, and stewardship. The NHD is commonly combined with other data themes, such as boundaries, elevation, structures, and transportation, to produce general reference base maps. The National Map download client allows free downloads of public domain NHD data in either Esri File Geodatabase or Shapefile formats. For additional information on the NHD, go to https://www.usgs.gov/national-hydrography/national-hydrography-dataset. See https://apps.nationalmap.gov/help/ for assistance with The National Map viewer, download client, services, or metadata. Data Refreshed January, 2024.

源自美国地质调查局（USGS）美国国家地图（The National Map）服务的国家水文数据集（National Hydrography Dataset，NHD），是一套覆盖全面的数字空间数据集，对天然与人工地表水体（湖泊、池塘与水库）、水流通道（运河、沟渠、溪流与河流）及相关点要素（泉、水井、水文测站与大坝）的信息进行编码。针对上述要素的编码信息涵盖分类与其他特征、要素轮廓、地理名称、位置及相关量测值、用于关联其他信息与NHD的“河段编码”，以及水流方向。通过河段编码勾勒的水体与输运物质流动网络，支持用户沿上游与下游方向追踪物质运移路径。除上述地理空间信息外，该数据集还包含支撑后续数据更新与优化的元数据。美国国家地图提供的NHD在全美范围内设有两套无缝数据集：一套基于1:24000（或更高）比例尺，被称为高分辨率NHD；另一套基于1:100000比例尺，被称为中分辨率NHD。该数据集可支撑制图、观测地理编码、水流模拟、数据维护与管护等诸多应用场景。NHD通常会与边界、高程、建构筑物、交通等其他专题数据图层结合，用于制作通用参考底图。美国国家地图下载客户端支持以Esri文件地理数据库（File Geodatabase）或形状文件（Shapefile）格式免费下载公有领域的NHD数据。如需了解NHD的更多详细信息，请访问https://www.usgs.gov/national-hydrography/national-hydrography-dataset。如需获取美国国家地图查看器、下载客户端、相关服务或元数据的帮助支持，请访问https://apps.nationalmap.gov/help/。本数据集于2024年1月完成更新。