Hydrologic Unit Subdivisions

Date: Fri, 2 Aug 1996 07:17:31 -0500
To: "DC - All District Chiefs"<distribution>
From: "George D Glysson, Hydrologist (Engr), Reston, VA" <gglysson> (Doug Glysson )
X-Sender: gglysson@130.11.51.82
Subject: Hydrologic Unit Subdivisions
Cc: "A  - Division Chief and Staff"<distribution>,
        "B  - Branch Chiefs and Offices"<distribution>


To: All District Chiefs, WRD

From: Doug Glysson, OWDC

Subject: Hydrologic Unit Subdivisions


As you know, there is a considerable amount of interest arising concerning
the further subdivision of the Hydrologic Units (HU's) below the 8 digit
Cataloging unit. Some of you received from me an email message awhile ago
concerning activity in your state in relationship to Natural Resources
Conservation Service (NRCS) work on subdivision of the HU's. I am now
requesting further information concerning this activity from all Districts.
Below are several questions that I would appreciate you taking the time to
answer. Please just answer the best you can, an estimate or guess is fine
if that is what it takes. This information will help us to know the status
of the WRD in this activity and give us some direction as to how to proceed
in our discussions with the other agencies. You can reply on this email and
return it to me. 

We are carrying out this work because we have been requested by NRCS to
facilitate the development of an interagency standard for hydrologic unit
subdivision.  Authority for this work derives from OMB Circular A-16 and
Memorandum M-92.01.

Thanks for you help, Doug


Questions:

1. Has there been any formal activity in your state to subdivide the HU's
below the cataloging unit ( i.e. the 8 digit number)? 

2. If so, what agencies have been involved, include Federal, state and
local if appropriate?

3. Are 11 and 14 digits being used or are 10 and 12 digits being used to
number these subdivisions? If 11 and 14 digits were or are being used,
could they be converted to 10 and 12 with out a large amount of redoing? 

4. What percentage of the state has been subdivided? Have the subdivisions
been placed in an electronic (GIS) file? 

5. Has the subdivision been done on a hydrologic basis or is some other
criteria been used? Have units been divided using streams as division lines
(i.e. different unit on one bank than on the other)? Are there stateline
faults?

6. Was the NRCS proposed national guidelines followed? ( These guidelines
can be found on the internet under the URL
http://www.nhq.nrcs.usda.gov/hu/intro.html.) 

7. Please provide us with a contact in your District for the HU's. Would
that person be willing to help by reviewing criteria and providing
technical input to us on the development of a finial set of criteria for
the delineation of these units.?

8. Any other comments or bits of information you think may be helpful to us. 

Please contact OWDC is you have any questions.

Doug Glysson
M/S 417
703/648-5019
703/648-5644 fax