• 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.
    • 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.
    • 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.
    • 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.
    • Hydrologic Factors Affecting Groundwater Management for the City of Tucson, Arizona

      Johnson, R. B.; Water and Sewer Department, City of Tucson, Arizona (Arizona-Nevada Academy of Science, 1978-04-15)
      Assessment of the basic hydrologic and geologic parameters controlling the occurrence and availability of local groundwater is one of the first steps in formulating any comprehensive water management plan. Each of several parameters must be carefully evaluated both individually and in relation to the other factors which together describe the occurrence and movement of the subsurface water resources. These evaluations are fundamental to the legal and political decision- making framework within which the Water Utility must operate for both short and long-range water management planning. Recent changes in several hydrologic parameters have been observed throughout much of the groundwater reservoir tapped by numerous users in the Tucson Basin. Accelerated water level decline rates, decreasing production capacities of existing wells, increased hydrologic interference and increased demand for water are all having an impact on our water resource. These conditions must be evaluated before basin -wide groundwater management alternatives can be implemented.
    • Management Alternatives for Santa Cruz Basin Groundwater

      Foster, K. E.; Office of Arid Lands Studies, University of Arizona, Tucson, Arizona (Arizona-Nevada Academy of Science, 1978-04-15)
      Combined urban, agricultural, industrial and mining groundwater withdrawal from the Santa Cruz River Basin exceeds natural aquifer replenishment by 74,000 acre -feet annually. Four ameliorative water management alternatives are presented singly and in combination with one another. These alternatives are importing Colorado River water, exchanging treated effluent with mining and agricultural interests for groundwater, interbasin water transfer, and retiring farmlands for groundwater rights. These management philosophies are applicable to most economically emergent urban areas in arid and semiarid regions.
    • Heavy Metals & Wastewater Reuse

      Higgins, T. E.; Department of Engineering, Arizona State University, Tempe (Arizona-Nevada Academy of Science, 1978-04-15)
      Water shortages in the Western United States have intensified the search for new sources. Wastewater reuse is being increasingly called upon to augment existing supplies. One potential impediment to the continued expansion of wastewater reuse efforts is the accumulation of toxic heavy metals and other salts in the recycled water. Conventional and advanced wastewater treatment effect the removal of a portion of the heavy metals added during use. Removal is by chemical precipitation and adsorption and disposed of with the sludges. Potential uses of treated wastewater effluents include irrigation and groundwater recharge. Care must be taken to prevent contamination of groundwater, especially since existing wells have been reported to have concentrations of heavy metals in excess of drinking water standards. Percolation of wastewaters through soils (especially fine soils) results in a reduction in heavy metal concentrations. It is postulated that removal of these metals is by a combination of chemical precipitation with filtration of the precipitates, and adsorption on soil particles (thus the effectiveness of fine soils). Long term saturation of the soils with heavy metals may result in a "breakthrough" contamination of the groundwater. A predictive model of heavy metal-wastewater-soil interactions is proposed to aid in the design and regulation of wastewater reuse systems to eliminate or minimize this problem.
    • Action Programs for Water Yield Improvement on Arizona's Watersheds: Political Constrains to Implementation

      Cortner, H. J.; Berry, M. P.; School of Renewable Natural Resources, University of Arizona; Department of Forestry, University of Wisconsin (Arizona-Nevada Academy of Science, 1978-04-15)
      Although the Arizona Watershed Program 's (AWP) research efforts have had considerable success over the past 22 years in its objective to further knowledge of the feasibility of vegetative manipulation and modification as a method of increasing surface water yields, its principal sponsor and supporter, the Arizona Water Resources (AWRC), has not, to date, met with similar success. Described are three of the AWRC 's unsuccessful attempts to implement on-going action programs of vegetative management for water yield improvement: The Barr Report, the Ffolliott-Thorud Report, and the Globe Chaparral controversy, to illustrate how overstated program goals, unrealistic assumptions about the political feasibility of treatment types, extent, and intensity; failure to recognize the emergence of significant new decision-making participants, and unsettled questions concerning program costs and beneficiaries have contributed to setbacks in these programs. It is suggested that political as well as scientific constraints have accounted for reported failures in the implementation of the AWP action program objectives.
    • 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)
    • Wastewater Reuse - How Viable is It? Another Look

      Chase, W. L.; Fulton, J.; Phoenix Urban Study, U. S. Army Corps of Engineers; Phoenix Office of Stevens, Thompson, and Runyan, Inc. (Arizona-Nevada Academy of Science, 1978-04-15)
      Even though the Phoenix Metropolitan Area is more fortunate than other areas of the desert southwest because of the dependable Salt and Verde River supplies, they still have water problems. The Central Arizona Project (CAP), which will bring water from the Colorado River, will help those problems. But the CAP will not eliminate them. Improved water resource management will be required to bring water supply and demand back into balance. A key element of any successful water resource management program must be wastewater reuse. The communities are studying reuse through their 208 water quality program and while they are discovering that many opportunities exist they are also discovering that there are also many problems to be solved.
    • 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.
    • 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.
    • 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.
    • 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.
    • Analysis of Wastewater Land Treatment Systems in the Phoenix Urban Area

      Ewing, R. L.; Boyle Engineering Corporation, Phoenix Brance Office (Arizona-Nevada Academy of Science, 1978-04-15)
      As a part of the ongoing Phoenix Urban Study, Federal legislation mandates that land treatment of wastewater be seriously considered as a treatment option. Land treatment is a particularly viable alternative in the Phoenix area because in this arid desert climate, all water is a scarce and valuable resource and land treatment offers a positive opportunity for the conservation of this resource. In addition, land treatment systems are generally less expensive and have lower energy requirements than other conventional treatment processes while resulting in comparable treatment. The analysis of wastewater treatment systems for populated urban areas necessitates the preliminary investigation and comparison of a large number of alternatives to allow for a realistic engineering and economic evaluation. The site specific nature of land application adds additional variables that must be considered. A preliminary systems approach indicated that to minimize the effect of a human judgement factor between sites and yet maximize the depth of the initial analysis, computer techniques should be utilized for analysis and data storage. A summary of this analysis with appropriate cost, power usage, land requirements and other pertinent factors will be presented.
    • Legal Aspects of Urban Runoff Development

      Chudnoff, D. A.; Department of Hydrology and Water Resources, University of Arizona, Tucson (Arizona-Nevada Academy of Science, 1978-04-15)
      The relationships between the separate disciplines of hydrology and law are analysed in this study into how water law and its strictures may impose upon the development of urban runoff in the metropolitan Tucson area. Brief descriptions of the doctrine of appropriation, diffuse surface waters and developed waters are presented to illustrate the complexities of the problem of urban runoff development. It is suggested that planners must not only be aware of the legal issues involved but also must understand the philosophy and principles of water law.
    • 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.
    • 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.