• Nitrogen Removal from Secondary Effluent Applied to a Soil-Turf Filter

      Anderson, E. L.; Pepper, I. L.; Johnson, G. V.; Department of Soils, Water and Engineering, University of Arizona, Tucson, Arizona; Soil Testing Laboratory, Oklahoma State University, Stillwater (Arizona-Nevada Academy of Science, 1978-04-15)
      This study investigated the potential of a soil-turf filter to renovate secondary effluent applied in excess of consumptive use. Lysimeter plots were filled with a sand and a sand mix, and seeded to winter ryegrass. In spring, plots were scalped and seeded to bermudagrass. Plots were drip irrigated twice a week with secondary effluent at rates of 10, 17, 22, 34, and 43 mm/day. Leachate and effluent were analyzed for NH -N, NO,-N, and organic-N. Grass clippings were oven dried, weighed, and analyzed for organic -N. Percent of leachate available for groundwater recharge was 50% at the lowest rate and 68% at the highest rate when values were averaged for both soils. The amount of nitrogen removed by the soil-turf filter using sand was 42 to 87% and 52 to 90% on the mix, decreasing as application rate increased. The highest nitrogen removal and utilization occurred at the lowest application rate. Turf utilization of nitrogen was 10 to 28% on sand and 18 to 36% on mix, decreasing as rate of application increased. The sand-turf filter renovated 22 mm/day and the mix-turf filter renovated 43 mm/day, yielding leachate averaging less than 10 ppm NO₃-N.
    • A Sediment Yield Equation from an Erosion Simulation Model

      Shirley, E. D.; Lane, L. J.; Southwest Watershed Research Center, Tucson, Arizona 85705 (Arizona-Nevada Academy of Science, 1978-04-15)
      Sediment is widely recognized as a significant pollutant affecting water quality. To assess the impact of land use and management practices upon sediment yield from upland areas, it is necessary to predict erosion and sediment yield as functions of runoff, soil characteristics such as erodibility, and watershed characteristics. The combined runoff-erosion process on upland areas was modeled as overland flow on a plane, with rill and interrill erosion. Solutions to the model were previously obtained for sediment concentration in overland flow, and the combined runoff-erosion model was tested using observed runoff and sediment data. In this paper, the equations are integrated to produce a relationship between volume of runoff and total sediment yield for a given storm. The sediment yield equation is linear in runoff volume, but nonlinear in distance and, thus, watershed area. Parameters of the sediment yield equation include the hydraulic resistance parameter, rill and interrill erodibility terms, and flow depth-detachment coefficient and exponent.
    • Current and Forecasted Water Consumption Patterns of Arizona Second-Home Owners

      Bond, M. E.; Dunikoski, R. H.; Bureau of Business and Economic Research (Arizona-Nevada Academy of Science, 1978-04-15)
    • Rising Energy Prices, Water Demand by Peri-Urban Agriculture, and Implications for Urban Water Supply: The Tucson Case

      Ayer, H. W.; Gapp, D. W.; Natural Resource Economics Division, USDA; University of Arizona (Arizona-Nevada Academy of Science, 1978-04-15)
      The city of Tucson, Arizona, the largest city in the U.S. to meet its water needs entirely from diminishing underground sources, is presently experiencing increasing water rates and the political turmoil associated with those increases. With focus upon this increasingly serious problem, production function analysis and static linear programming are used here to estimate the impact of rising energy prices on farm profits, cropping patterns and irrigation water used in the Avra Valley, a periurban irrigated region adjacent to Tucson, in an effort to evaluate the impact of this community upon Tucson 's municipal water demand. It is concluded that as energy prices increase and land is removed from agricultural production within the Avra Valley, Tucson 's economic position will be bolstered in at least three ways: (1) there will be more water available, (2) the price which the city must pay for farmland in order to gain control of the underlying water should be diminished and the quantity of farmland for sale increased, and (3) with fewer people involved in irrigated agriculture, legal conflicts between competing users will be diminished.
    • A Microroughness Meter for Evaluating Rainwater Infiltration

      Simanton, J. R.; Dixon, R. M.; McGowan, I.; United States Department of Agriculture, Science and Education Administration, Federal Research, Southwest Rangeland Watershed Research Center, Tucson, AZ 85705 (Arizona-Nevada Academy of Science, 1978-04-15)
      Described is a microroughness meter developed to obtain numerous and accurate measurements of rangeland surface microroughness and characteristics. The meter, which consists of four basic parts: (1) meter base and pin guide, (2) pin lifting support bar and lifting mechanism, (3) 100 vertically moving pins, and (4) stripchart support guide and winding mechanism, was designed to measure soil surface evaluations and characteristics of a 1m2 plot. Performance tests on multi-plot sprinkler infiltrometer studies conducted on the Santa Rita Experimental Range in southeastern Arizona indicated that the meter was accurate and relatively precise in repeating soil surface roughness measurements but was not precise in defining the theoretical characteristics of constructed surfaces. It was concluded, however, that these errors in precision were insignificant and due partly to surface geometry construction errors and that the meter is a convenient, quick, simple and accurate means of measuring surface roughness in studies requiring many plots and data points.
    • Geomorphic Features Affecting Transmission Loss Potential

      Wallace, D. E.; Lane, L. J.; Southwest Watershed Research Center, Tucson, Arizona 85705 (Arizona-Nevada Academy of Science, 1978-04-15)
      Water yield studies and flood control surveys often necessitate estimating transmission losses from ungaged watersheds. There is an immediate need for an economical method that provides the required accuracy. Analysis of relations between stream order, drainage area, and volume of channel alluvium existing in the various orders is one means of estimating loss potential. Data needed for the stream order survey are taken from aerial photos. Stream order is analyzed using stereophoto maps. Stream lengths taken from the maps are combined with average channel width and depth data (determined by prior surveys) to estimate volumes of alluvium involved. The volume of channel alluvium in a drainage network is directly related to the stream order number of its channels. Thus, a volume of alluvium within a drainage network (with a known transmission loss potential) may be estimated by knowing the order of each length of channel and the drainage areas involved. In analyzing drainage areas of 56-mi² or less, 70 to 75 percent of the total drainage network length is contained within first and second order channels; yet, these constitute less than 10 percent of the total transmission loss potential of the areas. Analysis of stream order and drainage area versus volume of alluvium relations allows preliminary estimates of transmission loss potential to be made for ungaged areas.
    • Salvaging Wasted Waters for Desert-Household Gardening

      Fink, D. H.; Ehrler, W. L.; U. S. Water Conservation Laboratory, Phoenix, Arizona 85040 (Arizona-Nevada Academy of Science, 1978-04-15)
      With the objective of determining if sufficient water would be salvaged by a typical desert, urban-household from normally wasted sources associated with the lot and household to adequately irrigate a garden and orchard, a 2000 sq ft house on a typical one fifth acre lot in three cities having climates similar to Phoenix, Tucson, or Prescott, Arizona was hypothesized and the amount of water available for yard watering calculated, provided that (1) only rainfall was available, (2) rainfall-runoff from covered areas associated with or adjacent to the lot was salvaged (roof, street, alley etc.), (3) gray-water from the household was utilized, (4) a portion of the lot was waterproofed to concentrate the runoff on the untreated portion, and (5) various combinations of the above were utilized to increase the amount of available water. It is demonstrated that these sources could be used singly or in combination to obtain the required amount of water with the actual amount available depending upon the precipitation, runoff and runon areas, runoff efficiency of the contributing area, and the number of people in the household. A number of horticultural plants are suggested that should best fit such an irregular irrigation scheme.
    • The Effects on Water Quality by Mining Activity in the Miami, Arizona Region

      Young, D. W.; Clark, R. B.; Arizona State Land Department, Water Rights Division, Phoenix, Arizona (Arizona-Nevada Academy of Science, 1978-04-15)
      Intensive strip and leach mining activity within a confined region usually causes environmental impacts both on the land and on water quality. Adverse water quality effects could be realized long after any mining activity has ceased due to the continuous leaching by precipitation of contaminants from spoils piles and leach dumps. The Miami, Arizona region is unique in its surface and subsurface hydrology. Two unconnected aquifers underlay the region with both serving as domestic (private and municipal) and industrial (mining) supply sources. The shallow floodplain alluvial aquifer is hydraulically connected to surface drainage from mine tailings and leach dumps. Several wells drawing from this aquifer have been abandoned as a municipal supply source due to severe water quality degradation. Water quality in these wells varies directly with precipitation indicating a correlation between surface drainage over and through tailings and leach piles. Expansion of spoils dumps into natural recharge pathways of the deeper Gila Conglomerate aquifer has raised concern that this aquifer may also be subjected to a long term influx of mine pollutants. Questions have also been raised concerning the potential effects of a proposed in situ leaching operation on the water quality of the conglomerate aquifer.
    • Water Quality of Runoff from Surface Mined Lands in Northern Arizona

      Kempf, J.; Leonhart, L.; Fogel, M.; Duckstein, L.; Department of Systems and Industrial Engineering, University of Arizona, Tucson; School of Renewable Natural Resources, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1978-04-15)
      Surface mining of coal in the western U.S. can cause problems of increased salinity and heavy metal contamination in runoff along with a lack of enough rainfall to sustain plant growth for reclamation. To facilitate the planning of reclamation efforts in such areas results are described of a water quality sampling experiment on the ponds and runoff at the University of Arizona Experimental Watershed on Black Mesa in northern Arizona. A systems theoretic framework is employed to model the watershed and the results of a computer simulation based on this model is used to indicate that salinity buildup could be expected over time, given a minimal change in watershed configuration, with possible development of fluoride contamination being of particular concern. Water quality tests of the pond water and runoff on Black Mesa indicated that the water is within Federal standards for drinking and irrigation, except for sodium and fluoride. It is suggested that if it is economically desirable, the collection of more data on the ponds could be used to develop a simulation model of pond subsystems along the lines of the methodology outlined in this analysis.
    • Effects of Rainfall Intensity on Runoff Curve Numbers

      Hawkins, R. H.; Watershed Science Unit, Department of Forestry and Outdoor Recreation, Utah State University, Logan, Utah, 84322 (Arizona-Nevada Academy of Science, 1978-04-15)
      The runoff curve number rainfall- runoff relationships may be defined in two ways: (1) by formula, which uses total storm rainfall and a curve number, but not intensity or duration descriptors; and (2) rainfall loss accounting using a 4, rate and a specific intensity duration distribution of the function i(t) = 1.5P(5(1 +24t /T)-(1/2)-1) /T, where i(t) is the intensity at time t for a storm of duration T. Thus, the curve number method is found to be a special case of φ index loss accounting. The two methods are reconciled through the identity 1.2S = φT, leading to the relationship CN - 1200/(12 +φT). The effects of rainfall intensity on curve number are felt through deviations from the necessary causative intensity - duration curve. Some sample alternate distributions are explored and the effects on curve number shown. Limitations are discussed.
    • Land Treatment for Primary Sewage Effluent: Water and Energy Conservation

      Rice, R. C.; Gilbert, R. G.; U. S. Water Conservation Laboratory, Phoenix, Arizona 85040 (Arizona-Nevada Academy of Science, 1978-04-15)
      Land treatment of secondary municipal wastewater is an economical and aesthetic method of upgrading water quality, if hydrologic and geologic conditions are favorable. Costly conventional secondary treatment, which requires large quantities of electrical energy, can be bypassed by applying the primary effluent directly to the land. Soil- denitrifying bacteria use the organic carbon in the primary effluent as an energy source for biodenitrification and nitrogen removal. Laboratory and field studies indicated the quality of renovated wastewater meets standards for unrestricted irrigation and recreational uses. Considerable savings, both in capital and energy costs, can be realized by land treatment of primary effluent.
    • Effect of Algal Growth and Dissolved Oxygen on Redox Potentials in Soil Flooded with Secondary Sewage Effluent

      Gilvert, R. G.; Rice, R. C.; U. S. Water Conservation Laboratory, Science and Education Administration-FR, U. S. Department of Agriculture, Phoenix, Arizona 85040 (Arizona-Nevada Academy of Science, 1978-04-15)
      Algal growth and oxygen evolution at the soil -water interface of soil recharge basins intermittently flooded with secondary sewage effluent (SSE) produced diurnal fluxes in dissolved oxygen (DO) in the SSE and redox potentials (Eh) in the SSE and the surface soil of the basin. The maximum daily DO-% saturation in the SSE during flooding ranged from 30 to 450 %, depending on the length of flooding and seasonal effects of temperature and solar radiation. Diurnal cycles of Eh in the SSE and the top 0 to 2 cm of soil indicated that oxygen production by algae and bacterial nitrifying and denitrifying reactions at the soil-water interface are occurring daily for limited periods during flooding and that these reactions might contribute to the net-N removal and renovation of SSE by soil filtration.
    • Rainfall-Runoff Relationships for a Mountain Watershed in Southern Arizona

      Myhrman, M.; Cluff, C. B.; Putnam, F.; Water Resources Research Center, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1978-04-15)
      A network of rain gauges and two recorder -equipped flumes were installed near the head of Cottonwood Canyon on Mt. Hopkins in the Santa Rita Mountains pursuant to a water development study for the Smithsonian Institution's Mt. Hopkins Astrophysical Observatory. The watershed is generally characterized by steep slopes, a dense evergreen woodland cover predominated by several species of oaks, isolated bedrock exposures and talus chutes. The watershed for the lower flume site comprises about 145 acres (58.60 ha) with an elevation range from about 6775 to 8580 feet (2,065 to 2,615 m). Rainfall-runoff measurements were made during the summer and fall of 1977. A runoff efficiency of 0.56 percent was calculated for the lower-flume watershed. However, since physical evidence of surface flow was found only in side drainages receiving runoff from culverts located along the Mt. Hopkins access road, a second calculation was made, using only the total area of contributing road surface as the watershed area. This yielded a runoff efficiency of 27.0 percent. The latter value, adjusted for infiltration on the slopes below the culverts, agrees well with measured efficiencies for compacted-earth water harvesting catchments. Based on the above, recommendations were made for developing a water supply system using the access road, modified to increase its effectiveness, as a water harvesting system and having two surface reservoirs for storage. A computer model was used to test the capability of the system to meet the projected water needs of the observatory.
    • The Compartmented Reservoir: Efficient Water Storage in Flat Terrain Areas of Arizona

      Cluff, C. B.; Water Resources Research Center, University of Arizona (Arizona-Nevada Academy of Science, 1978-04-15)
      The compartmented reservoir is presented as an efficient method of storing water in areas of Arizona having a relatively flat terrain where there is a significant water loss through evaporation. The flat terrain makes it difficult to avoid large surface- area-to-water-volume ratios when using a conventional reservoir. Large water losses through evaporation can be reduced by compartmentalizing shallow impervious reservoirs and in flat terrain concentrating water by pumping it from one compartment to another. Concentrating the water reduces the surface-area-to-water-volume ratio to a minimum, thus decreasing evaporation losses by reducing both the temperature and exposure of the water to the atmosphere. Portable, high-capacity pumps make the method economical for small reservoirs as well as for relatively large reservoirs. Further, the amount of water available for beneficial consumption is usually more than the amount of water pumped for concentration. A Compartmented Reservoir Optimization Program (CROP-76) has been developed for selecting the optimal design configuration. The program has been utilized in designing several systems including several in Arizona. Through the use of the model, the interrelationship of the parameters have been determined. These parameters are volume, area, depth, and slope of the embankment around each compartment. These parameters interface with the parameters describing rainfall and hydrologic characteristics of the watershed. The water -yield model used in CROP-76 requires inputs of watershed area, daily precipitation and daily and maximum depletion. In addition, three sets of seasonal modifying coefficients are required either through calibration or estimated by an experienced hydrologist. The model can determine runoff from two types of watersheds, a natural and /or treated catchment. Additional inputs of CROP-76 are the surface water evaporation rate and the amount and type of consumptive use.
    • Simple Time-Power Functions for Rainwater Infiltration and Runoff

      Dixon, R. M.; Simanton, J. R.; Lane, L. J.; Science and Education Administration, Southwest Rangeland Watershed Research Center, Tucson, AZ 85705 (Arizona-Nevada Academy of Science, 1978-04-15)
      The equations of Darcy, Kostiakov, Ostashev, Philip, and four modified Philip equations were evaluated for use in predicting and controlling rainwater infiltration and rainfall excess in crop and rangelands. These eight equations were least- square fitted to data from ring, border-irrigation, closed-top, and sprinkling infiltrometers. Kostiakov's equation satisfied the evaluation criteria better than the other seven equations. The parameters of Kostiakov's equation were physically interpreted by relating their magnitudes to some physical, biological, and hydraulic characteristics of the infiltration system. These characteristics included several infiltration abatement and augmentation processes and factors that are controlled at the soil surface by land management practices. The eight equations were also fitted to rainfall data to permit calculating runoff from small surface areas about the size of a typical crop plant. Comparison of the regression curves for infiltration and rainfall suggested that land management practices that appropriately alter the soil surface will permit wide-range control of infiltration, runoff, and erosion; and thereby achieve conservation and more efficient use of soil and water resources for crop production. The most important soil surface conditions affecting infiltration were microroughness, macroporosity, plant litter, and effective surface head.
    • Tucson's Tools for Demand Management

      Davis, S. T.; Water and Sewer Department, City of Tucson, Arizona (Arizona-Nevada Academy of Science, 1978-04-15)
      Tucson's "Beat the Peak" program implemented in the summer of 1977 effectuated a reduction in peak day water usage from 151.5 million gallons per day on July 9, 1976, to 114.0 million gallons per day on July 8, 1977. This twenty-five percent reduction, if maintained, will allow a three -year deferral of a new remote wellfield and transmission pipeline estimated to cost between $25 and $50 million. More time will be available to analyze the cost effectiveness of solutions to the region's water resources supply problems (such as imported groundwater, Central Arizona Project water, effluent reuse, and their interrelationships). Although conservation was not promoted, the successful peak management program resulted in a 13.3 percent reduction in 1977 water use during the summer months (May through August) compared to usage during the same period in 1976. This resulted in water sales revenues less than projected, but the combination of less utility expenses and deferred capital improvements will yield lower customer rates and monthly bills than would have otherwise been necessary without the program.
    • Water Quality Problem of the Urban Area in an Arid Environment, Tucson, Arizona

      Hansen, G.; Pima Association of Governments, 208 Water Quality Management Program (Arizona-Nevada Academy of Science, 1978-04-15)
      The U.S. Environmental Protection Agency 's two-year 208 area-wide Water Quality Management Study for Pima County, Arizona, is discussed in terms of the specific problems of municipal wastewater effluent, industrial wastewater, urban stormwater runoff, land disposal of residual wastes, septic systems, and construction activities related to the City of Tucson urban area. The primary groundwater and the slow cycling of the hydrologic system in this arid urban environment reduce many water pollution problems to insignificant levels in the short term, (2) there does exist significant long-term pollution problems in the area. These problems include urban stormwater runoff and landfill leachate, and are related to the pollution of groundwater recharge and aquifer water supplies, and (3) there is a strong need for total water resource planning in arid urban areas which includes planning for wastewater reuse, water harvesting, and proper management of groundwater recharge systems.
    • Ephemeral Flow and Water Quality Problems: A Case Study of the San Pedro River in Southeastern Arizona

      Keith, S. J.; Department of Hydrology and Water Resources Administration, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1978-04-15)
      Discontinuous water quality data for the San Pedro River in southeastern Arizona is analyzed to illustrate the nature of water quality problems of ephemeral flow. The San Pedro drains a northerly-trending basin of 4,483 square miles, of which 696 are in Mexico and 3,787 in Arizona. Several questions arise in the consideration of a rational management plan: what is the necessity for protection of ephemeral flow quality when the channel consists of a dry wash much of the year, where there is little aquatic or wildlife to protect, and where occasional flow during flood conditions is put to little use by humans; and where and how do we use the ephemeral flow it is indeed decided to utilize it. Such questions as these form the basis of this discussion in an effort to bring out the point that water quality problems of ephemeral flow in arid areas differ from those in the humid zone. It is argued that in between the extremes of prohibiting or treating all runoff or eliminating all sources of pollution, there is actually little that can be done to control all sources of pollution in this typical arid stream, despite the fact that standards, for the most part unattainable, have been set for this flow.
    • Solar Radiation as Indexed by Clouds for Snowmelt Modeling

      McAda, D. P.; Ffolliott, P. F.; School of Renewable Natural Resources, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1978-04-15)
      In an effort to improve the methods of forecasting the amount and timing of snowmelt, a primary source of water in Arizona, significant regression equations are developed over a selected measurement period to relate global, direct, and diffuse solar radiation to: (1) the cloud-cover of specific cloud genera, (2) the hour before or after solar noon, and (3) the potential solar radiation. Three regression equations are derived from cloud-cover imagery and solar radiation data collected from two sites in Arizona 's Ponderosa pine forests, Schnebly Hill, and Alpine, in the hope that regression models will be useful in the simulation of snowpack dynamics.
    • Arizona Groundwater Law Reform - An Urban Perspective

      Holub, H. (Arizona-Nevada Academy of Science, 1978-04-15)
      The recently- created Arizona Groundwater Management Study Commission is mandated to propose a reform of Arizona's groundwater laws. A number of issues must be addressed by this Commission in order to deal with urban problems with present groundwater law. These include: a comprehensive set of regulations on groundwater use to enhance the public interest and benefit in scarce groundwater resources; a permanent mechanism to permit transfer of water rights away from specific parcels of land; an effective system of management which considers differing types of water problems in various parts of the state; a method of quantifying existing rights and measuring use of groundwater; an extraction tax to recognize public costs associated with groundwater mining and the need for replenishment; a reevaluation of existing preferences and subsidies which encourage the mining of groundwater. Failure by Arizona to reform its groundwater laws threatens future funding for the Central Arizona Project and increases the possibility of federal intervention in state water management.