FLOOD10000

• County: Bent
• Community: Las Animas
• Stream Name: Arkansas River
• Basin: Arkansas
• Title: Las Animas Local Protection Project Design Memo Number 1 Hydrology
• Date: 9/1/1967
• Prepared For: Las Animas
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Project

solution of the synthetic unit hydrographs are from paragraph 20 of
EM 1110-2-1405. The area delineations and data pertinent to the unit
hydrographs are shown on plate 10. A graphic display of the unit hy-
drographs is shown on plate 11.

4-02. InfiZt~tion Zoss ~te8.- A review of infiltration studies
disclosed that accurate determinations of initial losses and average
loss rates could not be computed because of sparse coverage of precipi-
tation stations, lack of rainfall intensity data, and lack of suffi-
cient streamflow data. Therefore, runoff from rainfall was determined
from data successfully used in previous studies. in the Arkansas River
subbasin. Runoff was determined from the runoff-precipitation curves
displayed on plate 10. The curves have been used for reproduction of
floods in the Arkansas River subbasin and were used for reprojuction
of the 1921 flood at Las Animas. These curves were used and approved
for project document studies.

v - STANDARD PROJECT FLOOD ESTIMATES

5-01. CeneraZ.- A standard project flood is a flood which would
be exceeded only on rare occasions and in many instances defines the
upper limit of flooding against which protection would be sought. For
seasons when snowmelt is not a major consideration, the standard project
flood is the result of a storm which represents the most severe flood-
producing storm considered reasonably characteristic of the region.

5-02. Standard projeat storm.- Numerous storm studies were re-
viewed to determine the storm which would be applicable for use as the
standard project storm over the area under study. Among those examined
were:

Storm Study

Date

SW 2-23
SW 1-23
SW 2-8
MR 3-28A
Sri 2-18
SW 3-6
SW 2-20
SW 2-21
MR 6-15
MR 10-2
MR 3-29

18-19 Oct 1908
2- 6 Jun 1921
15-17 Aug 1932
30-31 May 1935
2- 6 Sep 1940
17-21 Apr 1942
2-12 May 1943
12-20 May 1943
10- 13 Jun 1944
9-13 Jul 1951
30-31 May 1958

Center

May Valley, Colorado
Pueblo, Colorado
Enid, Oklahoma
Cherry Creek, Colorado
Hallet, Oklahoma
Kenton, Ok lahoma
Warner, Oklahoma
Mounds, Oklahoma
Stanton, Nebraska
Council Grove, Kansas
Sharon Springs, Kansas

Appropriate transposition adjustments of precipitation values were esti-
mated for each storm by considering the differences in geographical
location, season, differential in inflow barrier elevation, precipitable
water, temperature contrast, and orographic effects.

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