RANGELANDS14(4), August 1992 217

National Study Mitch Flanagan

Of the many values and benefits managers need to better understand and integrate the data into Water that come from , water is these relationships in orderto achieve Prediction Project (WEPP) becoming increasingly important. the desired water quantity and qual- technology and appropriatetechni- Society's demandsfor improvedwater ity that could result from specific cal and scientific documents. quality and quantity requires range range sites. to have moreinformation Purpose managers A regarding the effect of rangeland Cooperative Study The purpose of this study is to: (1) vegetation, erosion,and soilson the The USDA Conservation Ser- determine hydrologicdifferences of quality and quantity of the nation's vice (SCS) and AgriculturalResearch contrasting plant communities on water supply. Service (ARS) have entered into a extensivephases of soil serieswhich Complexinteractions between soil cooperativeefforttoimprove the under- representthe most important range and vegetationfactors influencethe standingof the plant, soil, and water sites; (2) use the data collected to hydrologic condition of rangelands. relationships and to develop data validateand enhancethe WEPP model Theseinteractions will not onlyvary bases and quantitativemethods for for rangelands;and (3) developWEPP from site to site but also within sites evaluating rangeland watershed man- parameter data sets for use by the of varying condition. The various agement. Through this effort, the SCS and others. kinds of vegetation, plant cover, and SCS National Range Study Team can be correlated to rates of (NRST) and the Interagency Range- DesIgn erosion, infiltration, and runoff. Range land Water Erosion Team (IRWET) The project has been designed to were formed. The NRST was formed evaluate two or threerangeland plant Author is range conservationist team leader, National Range Study Team, Midwest National to collect the data while the IRWET, communities on 15 different soils. Technical Center,Soil ConservationService, Lin- which will coln. NE68508-3866. is comprisedof ARS and SCS Each soil chosen be represented personnel, was formed to analyze by a phase of a series which is

Rainfallis uniformly simulated on a 50ft diameterarea, over twolarge (3.05 X 10.7m) plotsand two small(0.61 X 1.22 m) plots.

,__iull1iP 218 RANGELANDS14(4), August 1992

Canopy, ground cover, andrandom ground surface roughnessare determined by point sampling with a 49-point frame. index, ground and canopy cover, plant heights,canopy diameters, plant shapes, average distances between Completesoil descriptionsand soil char- plants, average plant densities,and acterizationare completed at each site. plant compositionrecords. The ran- dom roughness of the ground sur- located in the same landscape posi- face is also recorded. The hydrologic tion. The study began in 1990 and data include rates of rainfall and will be conductedthrough 1994.The runoff and production. WEPP procedures developed by the Data have been collected on sites ARS are being used to collect the in Nebraska, Texas, Kansas, Wyom- data using a . ing, and Colorado. The NRST plans Soil moisture content and bulk to spend the 1992 field season col- density are being collected before lecting data in North Dakota, Wyom- and after each rainfall simulation. ing, Idaho, and Arizona. Sites in Colo- Soils are completelycharacterized in rado, Utah, Nevada, California, and one excavated pit to a depth of 150 other states are planned for subse- cm orto the root limiting layerandto quent years. 50 cm in four additional pits at each site. Implications Belowg roundroot biomass is being The data collected by the NRST measured. Soil albedo and soil will be analyzed by the IRWET to strengthdata are beingcollected. En- determine the relationships between gineering test data are being col- the variouscharacteristics of range- lected for the soil surfacelayer. The land watersheds. This information National Soil Survey Laboratoryand will be incorporated into the WEPP theSoil MechanicsLaboratory in Lincoln, model. This model will be used by Nebraska, will complete all soils an- the SCS and others to provide range Sedimentand watersamples arecollected. alysis. managers with reliable information Thevegetative databeing collected with which tomanage rangeland water- consist ofstanding biomass, leafarea sheds for increasedsupplies ofhigher quality water.