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
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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 firstname.lastname@example.org.
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.
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Sediment Production from a Chaparral Watershed in Central ArizonaHook, Thomas E.; Hibbert, Alden R.; Department of Geography, Arizona State University, Tempe; USDA Forest Service, Rocky Mountain Forest and Range Experiment Station. Research Work Unit, Tempe (Arizona-Nevada Academy of Science, 1979-04-13)Sediment production from two chaparral watersheds in central Arizona during a period of heavy winter rainfall in 1978 was compared with sediment production over a 14-year period (1964-78). Results indicate sediment production from chaparral is primarily the result of seasonal periods of heavy precipitation and runoff and not from ephemeral summer rainstorms. Sediments from 300 acres (122 ha) above a newly constructed stock watering tank were produced within a few days time in the late winter of 1978 at an accelerated annual rate of 41.1 ft /acre (2.9 m /ha). The sediments came mostly from cutting in channel alluvium in upstream tributaries where the sediments are presumed to have accumulated from downslope creep, dry ravel, and overland flow produced by ephemeral, convective rainstorms. The accelerated rate of sediment production was more than 4 times the average annual rate of 9.8 ft /acre (0.7 m /ha) determined from 14 years of cumulative sediment deposits in a stock tank constructed in 1964.
Application of Sediment Transport Theory in Environmental Science and EngineeringDuan, Jennifer G.; Zhou, Kang; Lansey, Kevin E.; Valdes, Juan B.; Gerba, Charles P. (The University of Arizona., 2019)Sediment exists in different water bodies and its transport can be associated with different problems such as irrigation water contamination and infrastructure integrity compromise. Applying sediment transport theory helps better understand and solve these problems. Therefore, this dissertation reports on the experimental investigation of pathogenic microorganism resuspension and bridge pier scour based on sediment transport theory. The first research focused on the study of the resuspension of Escherichia coli and MS2 bacteriophage from bed sediment in irrigation canals. A set of laboratory experiments was conducted to investigate relation between the concentration of Escherichia coli and the MS2 in moving water and flow properties and the size of bed sediment. Results showed when bed material is sandy loam, their quantity in water increases with the shear stress on bed surface. However, for a sandy bed, their presence in water has no apparent correlation with flow properties. The amount of MS2 virus in water was greater at low flow velocity and shear stress than Escherichia coli because the size of the MS2 virus is much smaller. Finally, an empirical relation was formulated for calculating the maximum allowable Escherichia coli concentration in sandy loamy bed sediment. The second research focused on the investigation local scour around a group of three piers with different sizes, spacing, and attacking angles. The results of the scour pattern showed the sheltering effect of the upstream piers and interaction between horseshoe vortex and wake vortex. Based on the phenomenological theory of turbulence flow, an analytical equation was formulated for predicting the maximum scour depth. The significance of key parameters were evaluated using the statistical F-test. The coefficients in the equation were determined by the experimental data from this and other studies. The results showed pier diameter, pier spacing, actual pier width, flow depth, Froude number, and sediment size are important parameters for determining the maximum scour depth. The third research focused on the study of the turbulence flow field around the three pier group. Mean flow vectors, turbulence intensities were analyzed based on the instantaneous velocity measured by Acoustic Doppler Vectrino Profiler. Two pier spacings of 1 and 5 times the pier diameter and two attack angles of 0 and 30 were used to study the effect of pier spacing and attack angle on the flow field. A strong sheltering effect of upstream pier in tandem alignment was observed when piers spacing is small. Horseshoe vortices around the middle and downstream piers were enhanced when the piers were in staggered alignment. Distributions of bed shear stress showed that when the scour is in equilibrium, the bed shear stress in the scour hole is smaller than the approaching bed shear stress.