Attributes

Average Water Elevation

The general location of the land/water transition of a controlled feature. Should  be noted with the Elevation attribute set and feature level metadata.

Date of Photography

The land/water transition as of the date of photography. Orthoimagery used must  be noted in the feature level metadata.

Elevation

The vertical distance from a given datum.

Ephemeral

Fcode

Ftype

Each NHD Feature Class is broken down by feature type (Ftype) which have a 3-digit coded value and a name.

GCS NAD 83

A Geographic Coordinate System called the North American Datum of 1983. This is the Coordinate system the NHD comes in when you download it.

General Case

A closed feature used to channel flowing water to another site

High Resolution NHD

A feature-based database containting surface water features for the United States at a scale of 1:24,000 and higher.

High Water Elevation

the highest elevation where a waterbody feature and land meet. Normally used when  a feature is controlled by a dam and may not match orthoimagery.

Hydro Net

Intermittent

Local Resolution

A feature-based database containting surface water features for the United States at a scale higher than 1:24,000.

Medium Resolution NHD

A feature-based database containting surface water features for the United States at a scale of 1:100,000.

National Hydrography Dataset

A digital vector dataset representing surface water features for the United States.

NHD GeoEdit Tools

NHD Viewer

N

NID

National Inventory of Dams- the NHD Derives its Dams from this database.

Normal Pool

The general location of the land/water transition uncontrolled feature.

NWIS

National Water Information System. The NHD Derives it's Water Quality Monitoring Stations and Stream Gages from this database.

Partner

Perennial

Resolution

Scale

Scale is the relationship between distance on the map and distance on the ground. For example, if the scale is 1:24,000, 1 map unit would represent 24,000 ground units.

Spillway Elevation

The elevation at which overflow from the feature will exit through the spillway.

Stage

Height of water surface.

Watershed Boundary Dataset

A dataset containing Hydrologic Units that define drainage areas for suraface water.