Watershed & Network Analysis Flashcards
Watershed
The entire land area contributing to the water flow at an outlet or stream junction.
Contributing Watershed
a watershed based upon an arbitrary point of interest (a dam, etc.)
Blue Lines
a cartography term for streams.
NHD: National Hydrography Dataset
A dataset that contains water bodies and streamlines for the United States.
Flowlines
the streamlines contained within NHD
WBD – Watershed Boundary Dataset –
a dataset containing nested watershed boundaries for the United States
NHDPlus
an enhanced version of NHD that adds additional attributes for each streamline, such as contributing area, flow, elevation, WBD, etc. Often used in place of NHD.
HUCs – Hydrologic Unit Codes
the watersheds created by the WBD. Usually designated by their size with the digit length (2,4,6,8,10,12) indicating the scale with 12 being the most specific and refined. HUC8s in CA are likely familiar, and HUC12 are useful for refined scale mapping.
Network Datasets
a specialized data model used to represent networks (roadways, rail networks, trail networks, etc.) in ArcGIS. A network dataset is required input for using the tools in the Network Analyst Extension.
Junctions
The point were two lines/edges of a network meet.
Edges
The lines of a network dataset
Impedance
the travel cost associated with a network edge or junction. This is usually represented as a travel time or travel distance.
Routing
The process of identify the path along a network between two locations
Service Area
The area that can be reached within a specified cost (travel time or travel distance) from a starting location.
