FLOOD04688

• County: Otero
• Community: La Junta
• Basin: Arkansas
• Title: Flood Preparedness Plan Arkansas River
• Date: 9/1/1993
• Prepared For: Otero County
• Floodplain - Doc Type: Floodplain Report/Masterplan

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2. BASIN CHARACTERISTICS

2. 1 General Hvdroloaic DescriDtion

La Junta is located in the Arkansas River Valley in the
southeastern section of colorado, approximately 64 miles east
of Pueblo. It is the county seat of Otero County and is in the
east-central portion of Otero County.

The climate in the study area of La Junta is semiarid.
Average annual precipitation is 12.31 inches based on 72 years
of record at Rocky Ford, seven miles west of the watershed.
Periods of drought are C01ll\llOn, as a result of the uneven
distribution of precipitation. Variations occur from year to
year as well as within any given year. The greatest daily
precipitation of 6.20 inches occurred on July 8, 1893. The
principal source of precipitation is high intensity, short
duration convection type thunderstorms occurring over limited
areas. Recorded temperature have varied from a low of -40
degrees Fahrenheit to a high of 114 degrees. The mean daily
temperature is 52.5 degrees Fahrenheit.

The Arkansas River above Pueblo is a typical mountain
stream which descends over 6,000 feet in elevation in a
distance of less than 130 miles, at gradients often exceeding
50 feet per mile. Between La Junta and Pueblo, the valley is
generally narrow and the streambed well-defined with a
gradient ranging from 10 to 23 feet per mile. The river
valley widens below Pueblo and varies in width from one to
three miles throughout eastern Colorado. In this reach, the
gradient fluctuates between five and nine feet per mile, with
an average of about 6.7 feet per mile in the study reach of La
Junta. The land immediately adjacent to the river has heavy
growths of trees and brush. The Arkansas drainage area above
River Mile 1,198.1 at La Junta is 12,210 square miles.

In the study area, the flood plains north of the
Arkansas River are approximately one mile in width, very flat
and bordered on the north by low bluffs or hills. The flood
plains south of the river vary from one-fourth to one-half
mile in width. Hills on the south side rise more gradually
than on the north, with an average rate of rise of about 125
feet per mile. Land along the north side of the river is
largely agricultural although for approximately one mile,
through North La Junta and La Junta Gardens, the area is
fairly densely developed as a residential area. The city of
La Junta occupies approximately two miles of the land on the
south side of the river while the land east and west of the
city is used for agricultural purposes, either grazing or
cultivated.

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Arkansas River tributaries in the La Junta area include
Anderson and King Arroyos. Both arroyos are right bank
tributaries and originate south of La Junta, flow through the
edges of the city and enter the Arkansas River about 1.3 miles
apart.

Anderson Arroyo on the west side of La Junta runs
parallel to King Arroyo on the east side of the city.
Anderson Arroyo has been shaped to some extent in the lower

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