• 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.
    • 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.
    • 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.
    • 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.
    • Wastewater Effluent - An Element of Total Water Resource Planning

      Goff, J. D.; Boyle Engineering Corporation, Phoenix Brance Office (Arizona-Nevada Academy of Science, 1978-04-15)
      Wastewater reuse options for the Phoenix area include: agricultural irrigation, fish and wildlife enhancement, ground water recharge, industrial processing and coiling water, recreation, cooling water for power generation stations, and exchanging effluent for additional water supplies. Consideration is given to effluent reuse potential as a commodity to exchange for water suitable for domestic water supply. This exchange would result in yet additional reuses of the water as title to the effluent could be assured by contracts and agreements.
    • 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.
    • Effectiveness of Sealing Southeastern Arizona Stock Ponds with Soda Ash

      Osborn, H. B.; Simanton, J. R.; Koehler, R. B.; USDA, SEA-FR Southwest Rangeland Watershed Research Center, Tucson, Arizona 85705 (Arizona-Nevada Academy of Science, 1978-04-15)
      Pond seepage losses are a particularly serious problem in the semiarid southwest where runoff-carried calcium normally causes well-dispersed clay particles to aggregate and increase the porosity of stock pond sediments. Reported are the results of laboratory and field tests carried out by the USDA Water Conservation Laboratory in Phoenix, Arizona to determine the success of sodium carbonate (soda ash) as a soil sealant and to establish criteria for its use. Following tests two leaky ponds on Walnut Gulch, Arizona were treated with soda ash broadcast over the dry pond surfaces to the spillway elevation at a rate of 3365 Kg/ha and mixed with the pond sediment to a depth of 10 cm with a disc. Seepage losses were compared following the summer rainy season, and generally represent 20 day periods in September or October when the summer monsoon rains have ended. The late season seepage loss for the after treatment period each year from 1968 through 1974 was reduced about 50% and the treatment on one pond seems to have lasted much longer than anticipated, thus increasing the value of the treatment. A pretreatment laboratory seepage test is suggested to better determine the likelihood of treatment success.
    • 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.
    • 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.
    • 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)
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.