Hydrology and Water Resources in Arizona and the Southwest, Volume 08 (1978): Recent submissions
Now showing items 21-30 of 30
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Effectiveness of Sealing Southeastern Arizona Stock Ponds with Soda AshPond 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.
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The Compartmented Reservoir: Efficient Water Storage in Flat Terrain Areas of ArizonaThe 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.
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Effects of Rainfall Intensity on Runoff Curve NumbersThe 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.
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Action Programs for Water Yield Improvement on Arizona's Watersheds: Political Constrains to ImplementationAlthough 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.
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Nitrogen Removal from Secondary Effluent Applied to a Soil-Turf FilterThis 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.
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Land Treatment for Primary Sewage Effluent: Water and Energy ConservationLand 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.
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Analysis of Wastewater Land Treatment Systems in the Phoenix Urban AreaAs 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.
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Arizona Groundwater Law Reform - An Urban PerspectiveThe 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.
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Tucson's Tools for Demand ManagementTucson'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.
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Hydrologic Factors Affecting Groundwater Management for the City of Tucson, ArizonaAssessment 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.
