• Nitrogen Species Transformations of Sewage Effluent Releases in a Desert Stream Channel

      Sebenik, P. G.; Cluff, C. B.; DeCook, K. J.; Water Resources Research Center, University of Arizona (Arizona-Nevada Academy of Science, 1972-05-06)
      A preliminary study was made with the objective of examining nitrogen species transformations of treated sewage effluent releases within the channel of an ephemeral stream, the Santa Cruz River of southern Arizona. Water quality samples were taken at established locations in sequence so that peak daily flows could be traced as the effluent moved downstream. Results indicate that increased nitrification, coinciding with changing stream characteristics, starts in the vicinity of Cortaro Road (6.3 river miles from the Tucson Sewage Treatment Plant discharge). Through physical-chemical changes in streamflow, nitrate -nitrogen values reach a maximum at approximately 90-95 percent and 60-80 percent of total flow distance for low flows and high flows, respectively. Concentrations of ammonia-nitrogen and total nitrogen decrease continuously downstream with both high and low flows. Therefore, the rate of nitrification within sewage effluent releases in a desert stream channel evidently is related to flow distance and physical characteristics of the stream.
    • A Proposed Model for Flood Routing in Abstracting Ephemeral Channels

      Lane, Leonard J.; Soil and Water Conservation Research Division, Agricultural Research Service, USDA; Arizona Agricultural Experiment Station, Tucson, Arizona; Southwest Watershed Research Center, Tucson, Arizona 85705 (Arizona-Nevada Academy of Science, 1972-05-06)
      Almost all runoff from semiarid rangeland watersheds in southern Arizona results from intense highly variable thunderstorm rainfall. Abstractions, or transmission losses, are important in diminishing streamflow, supporting riparian vegetation and providing natural groundwater recharge. A flood routing procedure is developed using data from the walnut gulch experimental watershed, where flood movement and transmission losses are represented by a system using storage in the channel reach as a state variable which determines loss rates. Abstractions are computed as a cascade of general components in linear form. Wide variation in the parameters of this linear model with increasing inflow indicates that a linear relation between losses and storage is probably incorrect for ephemeral channels.