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VHD FAQ Page
Please submit any questions you have that others may benefit from.
Q.1: How do I start to use the VHD?
Q.2: What are the best NHD features to use for making a simple map?
Q.3: What are the differences between the "NHDinARC", "NHDinGEO" and "NHDGEOinARC" data models used to represent the NHD standard?
Q.4: << to be developed >>
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A.1: Ultimately, to save yourself time and headache it
is best to start by reading the following resources even if all you
want to do is make a simple map. Being penny wise and dollar foolish in this regard will come back to haunt you in any number of ways. The VHD is far superior to ANY other
statewide surface water data layer so it's worth learning how to use.
Read the following: 1) "Introducing
the NHDinARC" under the "Technical References" section of the NHD homepage; and 2) the VHD
metadata located on the Vermont Geographic Information System website.
A.2: If you don't want to use the NHDArcView Toolit
extensions to automatically load the VHD (NHDinARC) then decide between
the Route.RCH and Route.DRAIN features for representing "1D" features,
e.g., streams and the Region.Rch and Region.WB features for
representing "2D" features, e.g., lakes, rivers & ponds. The
Route.RCH has reach code and name attributes, whereas, the Route.DRAIN
contains the individual feature "type" attribute. Similiarly, the
Region.RCH has reach code and name attributes and the Region.WB
contains the individual feature "type" attribute.
A.3: The NHDinARC data model is coverage based and
was the first implementation of the NHD. It has been replaced by the
NHDinGEO data model, based on the ESRI GeoDatabase model. NHDGEOinArc
is extracted from NHDinGeo, explaining why there are some fundamental
differences between it and NHDinARC. The difference between these
data models and reasons driving the progression to NHDinGEO are
explained in detail at the NHD Geodatabase page.
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Contact Info
If you have any questions or comments regarding the VHD FAQ page please feel free to
contact Mike Brouillette, surface water data manager, via e-mail , phone (802) 882-3008 or
fax (802) 882-3001.
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