OSo~o6/.~j
~/ COMMISSIONERS' COURT AGENDA REQUEST
PLEASE FURNISH ONE ORIGINAL AND TEN COPIES OF THIS
REQUEST AND DOCUMENTS TO BE REVIEWED BY THE COURT.
MADE BY: Leonard Odom
MEETING DATE: May 8, 2006
OFFICE: ROAD & BRIDGE
TIME PREFERRED:
SUBJECT: Consider, discuss and take appropriate action to have the 1978
"Simplified Method to Establish Base Flood Elevations" for Kerr County updated
and to consider a Workshop on Floodplain.
EXECUTIVE SESSION REQUESTED: (PLEASE STATE REASON)
NAME OF PERSON ADDRESSING THE COURT: Leonard Odom
ESTIMATED LENGTH OF PRESENTATION: 15 minutes
IF PERSONNEL MATTER -NAME OF EMPLOYEE:
Time for submitting this request for Court to assure that the matter is posted in
accordance with Title 5, Chapter 551 and 552, Government Code, is as follows:
Meeting scheduled for Mondays:
THIS REQUEST RECEIVED BY:
THIS REQUEST RECENED ON:
5:00 P.M. previous Tuesday.

All Agenda Requests will be screened by the County Judge's Office to determine if adequate
information has been prepared for the Court's formal consideration and action at time of Court
Meetings. Your cooperation will be appreciated and contribute towazds you request being
addressed at the earliest opportunity. See Agenda Request Rules Adopted by Commissioners'
Court.
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Kerr County Road & Bridge
4010 San Antonio Hwy
Kemille, Texas 78028
TO: COMMISSIONERS COURT
FROM: LEONARD ODOM
DATE: May 2, 2006
RE: Updating the Simplified Method to Establish Base Flood Elevations
In 1978 Colonel Burnie Bruns had the attached study done by Turner Collie & Braden Inc, to
help determine the Base Flood Elevations in unstudied areas. We aze still using this study today.
We have talked with Turner Collie & Braden, Inc. about the possibility of doing an updated
study. Anew study would not only help our department, surveyors, and engineers determine
BFE's; it would cost the average citizen much less if they are not required to do detailed
engineered studies; it would become the best available information for rural areas at the local
level.
The estimated cost is $17,440.00. Our current budget does not include any funds for floodplain
._, administration, but we do have $9,000 for flood damages. We ask that you consider allowing us
to spend those funds and pay the remainder out of flood reserves.
We would also like for you to consider setting up a workshop with other enfities during the
budget process to find out how the floodplain impacts them and how we might work together not
to duplicate services and have detailed studies done, in Zone A's (unstudied) that have the
greatest potential for development.
Th
cc memo for study
KERR COUNTY FLOODPLAIN ADMINISTRATION
SIMPLIFIED METHOD TO ESTABLISH BASE FLOOD ELEVATIONS
April 18, 2006
• Select streams where chart will be applicable
• Develop representative hydrology
Develop representative stream hydraulics
• Develop graphs and assumptions
• Prepare and issue report
Fee: $17,440
40 working days after notice to proceed
GEORGE 5. HARE
__ Project Director
~llrnerC~llie~r~c~~n Cn~. P.O•Boz13084
Houston, Tezas 77619
5757 Woodway
(7131780-4160
Telex 77-4185
March ~, I978 -~
Colonel B.W. Brune 1`~ /
Upper Guadalupe River Authority `
P.o. Box I278
Kerrville, Texas 78028
Re: Flood Depth Analysis
Approximate I00-Year Flood
Kerr county, Texas
Job No. 2084-030
Dear CoLanel Bruns:
The purpose of this letter is to present the method we have developed
for your use in determining the approximate elevations of 100-year
flood for small ungaged streams in Kerr County having drainage areas
less than 100 square miles where no detailed determination or analysis
has yet been performed. The attached Exhibit 1, brginage Area-Flood
Depth Curve shows the relationship between the total depth of the
I00-year flood above the stream bed and drainage area. The 100-year
flood elevation can be obtained by determining the drainage area and
channel hed elevation for any given locatioa from the U.S. Geological
Survey (USGS} 7~ minute quadrangle maps of the Kerr County area, and
adding the corresponding flood depth to the stream bed elevation.
The basic data used for preparing [he Drainage Area-Flood Depth Curve
were the detailed hydrologic and hydraulic studies of certain•Kerr
County streams perfartned by our firm .for the (load fnsurance studies
of the City of Kerrville and the unincorporated areas of Kerr County.
The streams involved in these detailed studies were Quinlan Creek,
Town Creek, Johnson Creek and the North and South Forks Guadalupe
River. The depth of the I00-year flood profile above the channel
bed was obtained from our detailed analysis at various paints along
the above named streams. The flood depths were plotted against
drainage area, stream slope and combinations of these [wo parameters
to obtain the most satisfactory relationship between stream character-
is[ics and flood depth. The best relationship obtained involved only
drainage area. Other factors, such as channel slope, roughness and
ConsultingEngineers AUSTIN
DALLAS
HOUSTON
Turn~rColli~~l3ra~en Cnc.
March 3, 1479
Cnlnnel B.W. Bruns
Flood Depth Analysis
Page Two
crass-aeetional area undoubtedly have a bearing on the flood depth.
However, for small Kerr County streams the differences in these para-
meters between the streams investigated evidently were too small
to influence the direct relation to the size of the drainage area,
We da not consider these curves applicable to urbanized areas.
Urbanization can be a significant factor in the flood discharge and
therefore, the flood depth, None of the detailed analysis we made
hats significant urbanization, FTowever, such restriction should not
bother you since you will not be considering urban areas.
General guidelines for the use of this curve are listed as follows;
..- 1. The drainage area at the point of interest on a particular stream
should be determined by delineating the contributing area upstream
of that point on the USGS 7~ minute quadrangle map and obtaining
the size of the area in square miles by planimetering or by some
other method of similar accuracy,
2. The stream channel bottom elevation should be obtained by inter-
polating the nearest foot between. the 26 foot interval contour
lines on the T~ minute quadrangle map,
3. The drainage area determined in Etem 1 should be used in the
Drainage Area-Flood Depth curve (Exhibit 1} to obtain the approx-
imate 160-year €lood depth, This flood depth should then be
added to the stream channel bottom elevation determined in Item
2 to obtain the approximate 160-year flood elevation.
4. The application of this curve should be limited to streams in
the Guadalupe River Basin within Kerr County.
5. This methodology should not be used to determine the 100-year
€lood elevation immediately upstream from bridges, culverts, dams
or stream confluences where significant backwater effects may
occur.
YurnerC©llie~h3r~.d~n Cnc.
Ylarch 3, 1978
Colonel B.W. Brune
Flood Depth Analysis
Page Three
Thank you for the opportunity to assist the Autharitq. Lf you have
any questions, please let me know
Very truly yours,
eorg~~e, P.E.
Unit birector
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