|
<br />~
<br />-.J
<br />W
<br />0)
<br />
<br />SNOTEL
<br />and Irrigation Water
<br />Management
<br />
<br />The Soil Conservation Service, USDA. is
<br />experimenting with a new use for their snow
<br />telemet<y (SNOTEL) system. SNOTEL is an
<br />automatic data collection system utilizing the
<br />meteor burst technique 01 radio signal
<br />transmiSSIon. This technique relies on the
<br />electrons in meteor trails to reflect radio
<br />waves for distances up to 1200 miles. The
<br />SNOTEL system consists of nearly 500
<br />remote data collection sites in ten western
<br />states. These sites gather information on
<br />mountain snow fall and snow pack. This data
<br />IS transmitted by radio from the remote data
<br />collection site skyward 10 the meteor region
<br />which is 50 to 75 miles above the earth. The
<br />signal is reflected by the electrons in the
<br />meteor trail to a ground master station. The
<br />drtta is forwarded from the master station by
<br />telephone 10 the central SNOTEL computer
<br />center in Portland, Oregon.
<br />While SNOTEL has been used
<br />successfully In gathering snowpack
<br />information for five years, SCS has begun
<br />testing the equipment for data gathering in
<br />the salinity studies. During the week of
<br />August 9 to 13, 1982, SCientific Engineering
<br />Instruments, Inc. o~ Sparv..s, Ne.'lada, installed
<br />a subtelemeteor system (POPCORN TM)
<br />This POPCORN system transmits data from
<br />a remote data point to a SNOTEL site by
<br />radio line of sight. The system is considerably
<br />cheaper than installing a complete SNOTEL
<br />site to do the same lob. The unit will transmit
<br />daily readings of wind speed and duration,
<br />sotar radiation, precipitation, mean
<br />temperature, humidity, salt moisture, and soil
<br />rem perature from an irrigated field in the
<br />Uinta Basin to the SNOTEL site high in the
<br />Uinta Mountains.
<br />Information received at Portland. Oregon,
<br />is then used to compute daily
<br />evapotranspiration rates and irrigation
<br />r8Cluirements for crops tn the vicinity of the
<br />POPCORN sites. This infonnation will be
<br />made available to local water users via the
<br />SCS computer tenninallocated in Salt Lake
<br />City, Utah
<br />If this arrangement proves satisfactory, it
<br />could be €xpanded to oth€r states using the
<br />SNOTEL communications network.
<br />
<br />Lower Virgin River Unit
<br />Concluded
<br />
<br />A March 1982 concluding report on the
<br />Lower Virgin River Unit indicates there is "no
<br />real potential for point source salinity control
<br />along the Lower Virgin River at this time."
<br />Consequefltly, the salinity control
<br />investigations for this unit have been
<br />terminated.
<br />The study originated as the Littlefield
<br />Springs Unit, a Title II point source study of
<br />the Colorado River Water Quality
<br />Improvement Program. The springs, on the
<br />Virgin River about 4 miles upstream of
<br />Littlefield. Ariz., have a cumulative flow of
<br />about 65 cls, with a salinity oi about
<br />2,500 mglL. Because the springs provide the
<br />only year-round source of irrigation water for
<br />Virgin River Valley lands near Littlefield and
<br />near the Nevada communities of Mesquite,
<br />BunkerviHe, and Riverside, local residents
<br />were oppoS@'j to any plan that would
<br />interrupt this water flOW during the dry
<br />months of the year. As a result. plans to
<br />control this point source of salinity were
<br />abandoned, and Reclamation planners and
<br />hydrologists proceeded to study saline
<br />underflows downstream of the irrigated
<br />areas. The unit then came to be known as the
<br />Lower VirgIn River Unit.
<br />As part of the s\udy, a line of observation
<br />wells was placed acroSS the alluvial valley fill.
<br />Instead of finding the expected 32.000 mglL
<br />water quality, the average salinity of the
<br />underflow was only aDout 3,000 mg/L, far
<br />less than needed to support a treatment or
<br />disposal project
<br />An analysIs was also made to de1ine \ne
<br />water and salt balances of the entire Lower
<br />Virgin River. As no conclusive evidence of
<br />salt loading from sources other than the
<br />Littlefield Springs was found, the stUdy was
<br />terminated and the concluding report issued.
<br />Concurrently with Reclamation's Studies,
<br />Ihe Department of Agr-jculture's Soil
<br />Conservation Service (SCS) has been
<br />studying possible salinity control in the
<br />Lower VIrgin River through improved
<br />Irrigation efficiency. The SCS identified a
<br />salinity control plan In its March 1982 report,
<br />''Salinity Control and Environmental
<br />Assessment. Virgin Valley, Subevaluation
<br />Unit. Arizona, Nevada, Utah, Colorado River
<br />Basin Salinity Control Program" The plan
<br />
<br />calls for improving the area's irrigation
<br />delivery system and water management plan,
<br />and reducing sediments through irrigation
<br />management.
<br />Reclamation, meanwhile. has initiated a
<br />water conservation plan along the Lower
<br />Virgin River. A recent demonstration project
<br />was started on vegetative management,
<br />which involves replacing phreatophytes with
<br />crops using less water. These crops should
<br />provide water savings through reduced
<br />evapotranspiration rates: they will also
<br />provide improved wildlife habitat
<br />A major effort of the study will be to
<br />quantify water saved by analyzing data from
<br />observation wells. Yet to be determined is
<br />whether the water saved will be used to
<br />reduce the salinity concentration of Virgin
<br />River water entering Lake Mead, or whether it
<br />will be used to increase agricultural
<br />production along the riller's lower reaches.
<br />
<br />California Builds Desalter
<br />
<br />Ground was broken April 2. 1982, at Los
<br />Banos. Califomia, by the Director of the
<br />Department of Water Resources for a
<br />386,000 gallon per day desalting plant. This
<br />may well open an era of water reclamation in
<br />California and make pOSSIble significant new
<br />contributions to the State Water Proiect's
<br />water supply.
<br />The desalter is expected to demonstrate
<br />feasibility of freshening agricultural drainage,
<br />both to reduce quantities of poor water to be
<br />disposed of in the environment and to add
<br />water of potable quality to the California
<br />aqueduct. This complex facility may be the
<br />launching pad tor a program to reclaim as
<br />much as 4OO,()X) acre-feet of agriculture
<br />drainage and other wastevoJaters in the next
<br />20 years.
<br />To prove technologies. to maximize
<br />efficiencies in pretre~tment, to select the
<br />most effective RO (reverse osmosis)
<br />processes through using membranes of
<br />several types and configuration under
<br />diHerent pressurizations, and to minimize net
<br />energy requiremen1s of the entire train, bo1h
<br />by solar ponds, energy recovery, and
<br />utilization of three stages of pressurization for
<br />RO units.
<br />The demonstrator will use brackish water
<br />from San Luis Drain, a faCIlity of Federal
<br />Central Valley Project. One million acres of
<br />
|