National Hydrography Dataset Plus Flowlines SCTDD

The National Hydrography Dataset Plus High Resolution (NHDplus High Resolution) maps the lakes, ponds, streams, rivers and other surface waters of the United States. Created by the US Geological Survey, NHDPlus High Resolution provides mean annual flow and velocity estimates for rivers and streams. Additional attributes provide connections between features facilitating complicated analyses. For more information on the NHDPlus High Resolution dataset see the User’s Guide for the National Hydrography Dataset Plus (NHDPlus) High Resolution. Dataset Summary Phenomenon Mapped: Surface waters and related features of the United States and associated territories Geographic Extent: SCTDD Region Projection: NAD 1983 Tennessee State Plane Visible Scale: Scales larger than 1:1,000,000 Source: USGS Data Vintage: February 2025 Publication Date: May 2026 This layer was symbolized in the ArcGIS Map Viewer and while the features will draw in the Classic Map Viewer the advanced symbology will not. Prior to publication, the network and non-network flowline feature classes were combined into a single flowline layer. Similarly, the Area and Waterbody feature classes were merged under a single schema. Attribute fields were added to the flowline and waterbody layers to simplify symbology and enhance the layer's pop-ups. Fields added include Pop-up Title, Pop-up Subtitle, Esri Symbology (waterbodies only), and Feature Code Description. All other attributes are from the original dataset. No data values -9999 and -9998 were converted to Null values.国家水文数据集增强高分辨率版（National Hydrography Dataset Plus High Resolution，以下简称NHDplus高分辨率版）绘制了美国境内的湖泊、池塘、溪流、河流及其他地表水体。该数据集由美国地质调查局（United States Geological Survey，简称USGS）研发，可为河流与溪流提供年均流量及流速估算数据。额外附带的属性字段可建立要素间的关联关系，助力复杂分析工作开展。如需了解该数据集的更多详情，请参阅《国家水文数据集增强高分辨率版用户指南》（National Hydrography Dataset Plus (NHDPlus) High Resolution User’s Guide）。 数据集摘要 制图覆盖对象：美国及相关领地内的地表水体与关联要素 地理覆盖范围：SCTDD区域 投影坐标系：NAD 1983田纳西州平面坐标系（NAD 1983 Tennessee State Plane） 可视比例尺：大于1:1000000的比例尺 数据来源：USGS 数据时效：2025年2月 发布日期：2026年5月 本图层已在ArcGIS地图查看器（ArcGIS Map Viewer）中完成符号化配置；尽管要素可在经典地图查看器（Classic Map Viewer）中加载显示，但高级符号化效果无法正常呈现。在正式发布前，本数据集已将网络流线与非网络流线要素类合并为单一流线图层；同理，面要素与水体要素类也已整合至统一的数据模式下。已为流线图层与水体图层新增属性字段，以简化符号化配置并优化图层的弹窗展示效果。新增字段包括弹窗标题（Pop-up Title）、弹窗副标题（Pop-up Subtitle）、Esri符号化配置（仅适用于水体要素，Esri Symbology）以及要素代码说明（Feature Code Description）。其余所有属性字段均源自原始数据集。已将无数据值-9999与-9998转换为空值（Null）。