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<br />Within the study limits, the north overbank of the Arkansas River <br />is approximately one mile in width, very flat and bordered by low <br />b1 uffs or hill s. The south overbank of the river varies from <br />one-fourth to one-ha1 f mile in width. Slopes on the south overbank <br />ri se more gradually than on the north overbank, with an average <br />rate of rise of about 125 feet per mile. Land along the nort.h <br />overbank of the river is largely agricultural, although the <br />residential areas of North La Junt.a and La Junta Gardens a1 so 1 ie <br />on the north overbanks of the Arkansas River. The City of La Junta <br />occupies approximately two square miles of the land on the south <br />overbank of the Arkansas. Lands east and west of the city are used <br />for agricultural purposes. <br /> <br />The Arkansas River tributaries considered in this study are King <br />and Anderson Arroyos. Both arroyos are right bank tributaries and <br />originate south of La Junta, flowing through the edges of La Junta. <br />King Arroyo flows almost due north along eastern portions of La <br />Junta and has a well-defined channel. The channel is approximately <br />ten feet deep throughout. The lower portion of King Arroyo, from <br />the Arkansas River to 3rd Street, has been partially shaped and <br />riprapped. The remainder is in a natural state, with the exception <br />of large amounts of junk and debris which have been dumped into the <br />channel in the vicinity of 14th Street. The channel has an average <br />slope of 24 feet per mile, and drains an area of about 25 square <br />miles at the Arkansas River confluence. Elevations in the <br />watershed range from 4,550 feet to 4,050 feet at its confluence <br />with the Arkansas River. <br /> <br />Anderson Arroyo flows north through La Junta, flowing through the <br />west side of the city. Like King Arroyo, Anderson Arroyo has been <br />shaped to some extent in the lower portion. In the vicinity of 5th <br />Street, to the upstream limit of the study area, Anderson Arroyo is <br />largely in its natural state. From 2nd Street to the study limit, <br />the arroyo is bordered on the east overbank by a relatively high <br />bluff or hill, with only a few locations where flood plains exist.. <br />The west side is generally flat and low, providing a flood plain of <br />several hundred feet. Anderson Arroyo wa tershed is about 15.5 <br />miles long and 3.5 miles in width, with a drainage area of about <br />54 square mil es at the Arkansas River. Elevations in this <br />watershed range from 4,750 feet mean sea level to 4,060 feet at its <br />confluence with the Arkansas River. The average slope is <br />approximately 19.4 feet per mile. <br /> <br />Storms over the upper Arkansas Basin can be characterized by <br />low-intensity, long-duration rainfall over a large areas, and short <br />duration and high intensity rainfall over a small areas. The <br />former are most prevalent during the autumn, winter and spring <br />seasons. Thunderstonns are most active during July and August, <br />although the two largest and most destructive floods of record <br />occurred during the month of June when general stonns concentrated <br />in a series of intense cloudbursts over the foothills and plains <br />areas. <br /> <br />5 <br />