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<br />watersheds are situated at the upper ends of tribl1tories
<br />and because the soils are easily eroded and transported.
<br />The vegetation at TIadger Wash is mainly of the salt.
<br />desert shmb type, with an understory of Il"alleta (HiZ.
<br />aria jame/l1'i) in the areas of coarsest soils. Dominant
<br />shmbs are shadscale (AtriplelJ ct>nfertifolia). Xuttall
<br />saltbush (AtriplelJ nuttallii). and rabbitbrush (Chry-
<br />sothamn,,, spp).
<br />Average annual precipitation at Badger Wash is
<br />about 8.5 inches. ~{ost of the sediment yield results from
<br />intense summer rainstorms (Lusby and others, 1963).
<br />Fifteen years of records on precipitation, runoff, and
<br />sediment yields were obtained from G. C. Lusby (writ:
<br />ten. commun., 1969).
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<br />New Mexico
<br />Five watersheds of this study are in the Cornfield
<br />Wash drainage about 55 miles northwest of Albuquer.
<br />que, X. Me:t. .
<br />Individual watersheds range from 0.29 to 7.33 square
<br />miles in size, and the entire 21.3-square-mile Cornfield
<br />"'ash drainage was also e,'aluated as one watershed.
<br />The soils are mainly fine sand)' loams deri,'ed from
<br />interbedded sandstones and shales .and nonnally con-
<br />tain roots to a depth of 2 to 3 feet. The range of slopes
<br />is similar to that of Badger Wash drainage, but the
<br />area of steep slopes (50 to 100 percent) is much less at
<br />the Cornfield Wnsh watersheds than it is at Badger
<br />Wash. The dominant plant on the upland in most water.
<br />sheds is galleta; but there is blue grama (BouteZt>ua
<br />gracilis) and big sagebrush. (A.rtemi.tia trideniata)
<br />mind with galletain some areas. The sandstone-
<br />capped ridgetops are usually covered with one.seed
<br />juniper (Juniperu8 mono.,perma). The bottom hmds of
<br />some of the basins have been o"ergrnzed for a number
<br />of ~..ears, and the perennial ,'egetation there has been
<br />replaced by Russian.thistle (Sa/sola kali).
<br />The anrage annual precipitation at Cornfield Wash
<br />is about 11 inches. July and August are the months of
<br />highest precipitation. The largest volume of runoff
<br />occurs in August, and lesser amounts occur in June,
<br />. July, and October, as shown by the 10-year record 1951-
<br />60 (Burkham, 1966).
<br />Two watersheds of 0.67 and 1.06 square miles, which
<br />are tributary to San Luis Wash, about 45 miles north.
<br />west of Albuquerque. X. ~Iex., were also rated. The
<br />morphology of these watersheds is characterized by
<br />large al1udal fans extending from the baseof a sand.
<br />stone escarpment. Roots penetrate 2 to 3 feet into the
<br />sand~' loam soils, and grass is the dominant vegetation.
<br />Blue grama, galleta. and alkali sacaton (Sporobolu8
<br />airoides) occur in vaIO'ing proportions, depending on
<br />soil moisture conditions. Scattered juniper (J "nipe""
<br />
<br />SHOWN
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<br />spp.) occurs on the escarpment, and scattered cholla.
<br />(O"i'"ntia Qrborescen8) occurs with the grasses on the
<br />inns. .\.nnual precipitation at these watersheds is about
<br />12 i11ohes: two-thirds of this occurs during the period
<br />~Iay through September (es. Weather Bureau, 1967).
<br />Sediment-yield records for these watersheds and for
<br />the Zia watershed. were taken from the small-watershed
<br />report by Peterson (1062).
<br />The Zia watershed is about 30 miles north of Albu-
<br />querque. X. ~{ex., just south of the Jemez :\Iountains.
<br />The 2.4-square-mile drainage is on a dissected, rocky
<br />terrace. The soil consists of sand mi:ted with gravel and
<br />cobbles. and it supports stunted juniper and some under.
<br />story of blue grama and snakeweed (Glttierrezia saro-
<br />thiae). The depth of root penetrl\tion is about 1 foot.
<br />Annual precipitation is about 10 inches, 6 inches of
<br />which occurs during the ~Iay through September pe-
<br />riod \ COS. Weather Bureau, 1967).
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<br />Wyoming
<br />The watersheds in the upper Cheyenne Rinr basin
<br />in east-central "'yoming are on shale, S3.ndstone. or
<br />interbedded formations containing both these rock types
<br />(Hadley and Schumm. 1961). Watershed areas range
<br />from 0.17 toi..>2 square miles. Soil te:ttures r.ange from
<br />,-ery sandy loam to clay, and roots penetrate most of
<br />the soils to a depth of 2 to 3 feet. Plant cover is pre.
<br />dominantly gross, but in some areas big sagebrush is
<br />mi:ted with the grass. Western wheatgrass (Agropyron
<br />smithii), blue grama, and grasslike sedges (CarelJspp,)
<br />are the major types found there.
<br />Annual precipitation is about 13 inches in the west-
<br />ern. sand~' part of the upper Cheyenne Rh'er basin and
<br />is 1 to 2 inches greater .in the area underlain b~' shale
<br />near the Wyoming-South Dakota border (('.5. Depart-.
<br />ment of Commerce, 1968). The highest monthly pre-
<br />cipitation O<'curs in ~[ay and June, with lesser amounts
<br />in April, July, August, and September. Cloudbursts
<br />are likel~' to occur in July, August, and September.
<br />Precipitation and sediment-yield information was ob-
<br />tained from the reports of Culler (1961) and Hadley
<br />and Schumm (1961). The sediment-yield records val')'
<br />in length from 7 to 25 years.
<br />The 37 -square.mile Logan Draw drainage above
<br />Rong;s Reservoir in the Wind Rh'er basin. about 30
<br />miles southeast of Riyerton, Wyo.. was the largest and
<br />most complex watershed e:tamined. The upper 70 per-
<br />cent of the watershed below the steep !.lce of the Bea\'er
<br />Rim has a gnwelly, silt loam soil resulting from the
<br />erosion and transport of a comple:t of sedimentary and
<br />metamorphic rocks. Roots penetrate to a depth of about
<br />:2 feet in this soil. Big sagebrush with an understor~'
<br />of junegrass (fiat/eria ai8tata) is the mnjor ,'eget"ti,'e
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