AffiliationTonto National Forest, Phoenix, Arizona
Southwestern Region, U.S.F.S., Albuquerque, New Mexico
KeywordsHydrology -- Arizona.
Water resources development -- Arizona.
Hydrology -- Southwestern states.
Water resources development -- Southwestern states.
Atterbury watershed (Tucson Ariz)
Universal soil loss equation
MetadataShow full item record
RightsCopyright ©, where appropriate, is held by the author.
Collection InformationThis article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact email@example.com.
PublisherArizona-Nevada Academy of Science
AbstractA stochastic model is presented for the prediction of sediment yield in a semi-arid watershed based on rainfall data and watershed characteristics. Random variables which lead to uncertainty in the model are rainfall amount, storm duration, runoff, and peak flow. Soil conservation service formulas are used to compute the runoff and peak flow components of the universal soil loss equation, and a transformation of random variables is used to obtain the distribution function of sediment yield from the joint distribution of rainfall amount and storm duration. Applications of the model are in the planning of reservoirs and dams where the effective lifetime of the facility may be evaluated in terms of storage capacity as well as the effects of land management of the watershed. In order to calibrate the model and to evaluate the uncertainties involved, experimental data from the Atterbury watershed near Tucson, Arizona were used.
Showing items related by title, author, creator and subject.
Accelerator Mass Spectrometry Radiocarbon Measurements on Marine Carbonate Samples from Deep Sea Cores and Sediment TrapsBroecker, Wallace S.; Klas, Mieczyslawa; Ragano, Beavan Nancy; Mathieu, Guy; Mix, Alan C.; Andree, Michael; Oeschger, Hans; Wölfli, Willy; Suter, Martin; Bonani, Georges; et al. (American Journal of Science, 1988-01-01)
Applicability of the Universal Soil Loss Equation to Semiarid Rangeland Conditions in the SouthwestRenard, K. G.; Simanton, J. R.; Osborn, H. B.; United States Department of Agriculture, Agricultural Research Service, Western Region, Southwest Watershed Research Center, Tucson, Arizona 85705 (Arizona-Nevada Academy of Science, 1974-04-20)An erosion prediction method that has recently received wide attention in the United States is the universal soil loss equation which is given as: a=rklscp. Where a = estimated soil loss (tons/acre/year), r = a rainfall factor, k = a soil erodibility factor, l = a slope length factor, s = a slope gradient factor, c = a cropping-management factor, and p = an erosion control practice factor. Data collected on the walnut gulch experimental watershed in southeastern Arizona were used to estimate these factors for semiarid rangeland conditions. The equation was then tested with data from watersheds of 108 and 372 acres. The predicted value of annual sediment yield was 1.29 tons/acre/year as compared with an average 1.64 tons/acre/year for 4 years of data for the 108-acre watershed, and a sediment yield of 0.39 tons/acre/year was predicted for the 372-acre watershed as compared with the measured value of 0.52 tons/acre/year. Although good agreement was noted between predicted and actual sediment yield, additional work is needed before the equation can be applied to other areas of the southwest.
Radiocarbon Age Offsets in Different-Sized Carbonate Components of Deep-Sea SedimentsThomson, John; Cook, G. T.; Anderson, Robert; MacKenzie, A. B.; Harkness, D. D.; McCave, I. N. (Department of Geosciences, The University of Arizona, 1995-01-01)We compared accelerator mass spectrometry (AMS) 14C ages of large (>150 micrometers) pelagic foraminifera with radiometric bulk carbonate 14C ages in two northeastern Atlantic cores. The foraminiferal ages are consistently older than those of the bulk sediment (by + 0.76 ka in Core 11881 and by + 1.1 ka in Core 11886), whereas corresponding fine (<5 micrometers) fraction ages are similar to those of the bulk sediment carbonate. We calculated near-identical sediment accumulation rates from both the foraminiferal and bulk sediment age/depth relations (3.0 cm ka-1 in Core 11881 and 5.9 cm ka-1 in Core 11886). Consideration of various factors that might produce such offsets leads us to believe that they are not artifacts, but were most probably caused by differential bioturbation of the different size-fractions in the sediment surface mixed layer. The importance of this finding is that many paleoceanographic records, such as the oxygen isotope record, also derive from analyses of large foraminifera, so that these records must be offset in time from the bulk of the sediments that they characterize.