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Showing 41 to 50 of 64 (0.064 seconds)Spelling suggestions: "subject:"grid bands"" "subject:"grid hands""
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Variability of Infiltration Characteristics and Water Yield of a Semi Arid CatchmentNnaji, Soronadi, Sammis, Ted W., Evans, Daniel D. 12 April 1975 (has links)
From the Proceedings of the 1975 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 11-12, 1975, Tempe, Arizona / Space-time variability in the hydrologic characteristics of four major soil series represented in the Silverbell validation site was investigated by sampling the infiltration characteristics, at randomly selected locations, under several vegetative covers within each series. The experimental data was the time distribution of infiltration which, for each sampled location, was fitted by least squares to the Philip's infiltration equation. The parameters of this equation have physical interpretation and therefore were used as measures of the infiltration characteristics. Analysis of variance was used to investigate the spatial variability in the parameters. The mean values of the parameters for selected soil-vegetation combinations were used to simulate runoff due to a rainfall event over a desert catchment "containing" the given combination. Statistical tests show that there is no significant difference among the infiltration parameters of all the soil-vegetation combinations. However, the statistically insignificant variations in the parameters produce significant variations in simulated runoff volumes indicating the sensitivity of the runoff generating process to infiltration characteristics vis-a-vis the hydrologic properties of the soils.
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| 42 |
An Energy Budget Analysis of Evapotranspiration from SaltcedarGay, L. W., Sammis, T. W., Ben-Asher, J. 01 May 1976 (has links)
From the Proceedings of the 1976 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 29-May 1, 1976, Tucson, Arizona / Energy budget evaluations of evapotranspiration from saltcedar were carried out on the flood plain of the Rio Grande River, near Bernardo, New Mexico. The site was adjacent to the Bureau of Reclamation's lysimeter study of water use by saltcedar. The energy budget for the cloudless day of June 14, 1975, revealed that energy gains from net radiation totaled 432 cal/cm² , while energy losses (in cal/cm2 ), were 14 to stored energy, 31 to convection, and 387 to evapotranspiration (ET). The energy loss to ET is equivalent to the latent energy contained in about 6.5 mm of water. The energy budget values are reasonable for a phreatophyte community in a semi-arid environment. The latent energy loss compares favorably with 401 cal/cm² measured by three lysimeters, although there were discrepancies in timing and amounts of loss among the individual lysimeters. The mean canopy diffusion resistance was 1.90 sec/cm over a 10-hour daytime period on June 14. The mean resistance was combined with vapor pressure deficit to predict lysimeter ET on three subsequent days. The agreement was within 12 percent, which suggests that diffusion resistance may be useful for simple ET predictions.
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Augmenting Annual Runoff Records Using Tree-Ring DataStockton, Charles W., Fritts, Harold C. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / Statistical analyses of existing hydrologic records suffer from the problem that such records are of relatively short duration, and therefore may not necessarily be random samples of the infinite population of events. On the hypothesis that tree-ring series and runoff series respond to a common climatic signal or signals that permit prediction of annual runoff from annual ring-width index, tree-ring data are used to extend available runoff records backwards in time to permit more accurate estimates of the 3 most common statistics used in hydrology: the mean, the variance and the 1st order correlation. It is assumed that both series are generated by the climatic parameters of precipitation, temperature, evapotranspiration, seasonal regime and spatial distribution. Of major concern in the reconstruction of annual runoff series from tree-ring records was the difference in persistence within each of the 2 series. A matrix of the tree-ring data was constructed, lagged up to 3 times and principal components were extracted. The covariation in this matrix was then decomposed by extracting the Eigen-vectors, and multiple regression was then used to weight the respective series and the differences in persistence were determined. This method was applied to watersheds of diverse characteristics and improved estimates of the mean and variance were obtained.
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Regional Differences in Runoff-Producing Thunderstorms Rainfall in the SouthwestOsborn, H. B. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / Quantitative descriptions of regional differences of rainfall amounts and intensities in the southwest, such as depth-duration frequencies, generally have ignored differences in the storm system that generated the rainfall and have lumped essentially different storm systems together. Thunderstorm rainfall in southern Arizona and New Mexico were analyzed using data from both recording and standard rain gages. The results were somewhat conflicting. Possibly because of more frontal activity and less distance from the Gulf of Mexico., the thunderstorms in eastern New Mexico can be more intense than those in southeastern Arizona. Recording rain gage records suggest that air-mass thunderstorms produce a larger number of more intense short-duration (about 1 hour or less) rains in southeastern Arizona than in other parts of southern Arizona. However, standard rain gage records from southern Arizona indicate that rainfall from individual air-mass thunderstorms may be greater in south-central Arizona than in se or sw Arizona. But frequency analysis of standard gage data from air-mass storms shows that the 100-year point rainfall is about 3 inches in all 3 regions. With more data becoming available, especially from remote areas, more exact separation of thunderstorm types and a better definition of rainfall will soon be possible.
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| 45 |
Sulfuric Acid: Its Potential for Improving Irrigation Water QualityBohn, H. L., Westerman, R. L. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The 2 major environmental problems of Arizona and the southwest are the alkalinization of soil and water by irrigation and air pollution from copper smelting. It is proposed that the amelioration of both problems may be solved through a common process. This is the production of sulfuric acid from sulfur dioxide, which is the main pollutant of smelter effluent gases. The conversion process is cheap and easy, and the sulfuric acid could then be added to irrigation waters to increase the solubility of CA carbonate in the soil, thereby decreasing alkalinity. Lower alkalinity results in increased soil permeability and increased water use efficiency by plants. The potential market for sulfuric acid in irrigation was calculated, on the basis of neutralizing 90% of the bicarbonate ion concentration in Colorado River water and Arizona well water, to be about 1.6 million tons annually, representing about 1/3 of the sulfur now dissipated by smelters as air pollution. This market includes both the Imperial Valley of California and the Mexicali Valley of Mexico, both of which are currently experiencing mounting salinity problems. Salinity itself is not amenable to this treatment, but the cumulative increase in NA and bicarbonate may be slowed and reversed, leading to gradual soil stabilization.
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| 46 |
Nitrogen Balance for a 23-Square Mile Minnesota WatershedJohnson, Jack D. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The nitrogen balance of a watershed near the city of New Prague, Minnesota was evaluated as part of an overall study on lake and stream eutrophication. Although the n-balance of a humid Midwest watershed cannot be expected to be identical to that of an arid watershed, the processes are the same and differences should be mainly quantitive. Sources of input and causes of depletion are reviewed for 4 points in the nitrogen cycle: the atmospheric zone, the soil-atmosphere interface, the plant-root and soil-water zone and the surface water zone. In the New Prague watershed, commercial fertilizer and bulk precipitation were the major sources of input, contributing, respectively, 53% and 34.4% of the total input of 2.34 million lb/yr. Crop yield and soil or groundwater storage contributed 52.1% and 20.4% of non-enrichment depletions. The closeness of the values of crop yield and commercial fertilizer application was an unfortunate coincidence and is certainly not an indication that the entire fertilizer supply was taken up cry crops. In an arid environment, free from fertilized agriculture, bulk precipitation probably provides the major source of nitrogen compounds.
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| 47 |
Management of Artificial Recharge Wells for Groundwater Quality ControlWilson, L. G. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / Recharge wells may be used in various problems relating to chemical water quality because of the phenomenon of in-aquifer mixing. This paper reviews specific recharge well-mixing techniques of possible utility in underground mixing operations for nitrate control. Illustrative data from field studies at a recharge site near Tucson, Arizona are presented. Both single- and 2-well types of mixing were investigated. In single-well operations, effluent recharge and pumping of the subsequent mixture occur at the same well. Differences in chlorine ion levels were used to distinguish between recharge effluent and native groundwater. Undiluted effluent was discharged in single-well operations until a pumped volume ratio of about 0.4 was attained. Dilution increased steadily with increased pumping and the relative concentration versus pumped volume curve was s-shaped. Seven-day pauses after effluent recharge resulted in immediate pumping of almost completely diluted water, probably because groundwater movement swept the effluent beyond the pumping unit during the pause. With 2-well pumping, the chlorine breakthrough curve reached a constant level at about 13 days and was close to that of the pause-type, single-well regime.
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| 48 |
Groundwater Contamination in the Cortaro Area, Pima County, ArizonaSchmidt, Kenneth D. 06 May 1972 (has links)
From the Proceedings of the 1972 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - May 5-6, 1972, Prescott, Arizona / High concentrations of nitrate have been found in water samples from irrigation wells north of the Tucson Arizona sewage treatment plant. The plant, which had primary treatment prior to 1951, produced 2,800 acre-feet of effluent in 1940, 4,600 acre-feet in 1950, 16,300 acre-feet in 1960, and 33,000 acre-feet in 1970. Large amounts of treated effluent recharge the groundwater system north of the plant. Sources of nitrate contamination beside sewage effluent may be sewage lagoons, sanitary landfills, meat packing and dairy effluent, septic tanks, and agricultural runoff. Sewage effluent is considered to be the primary source of nitrate contamination in the area. Geologic and flow net analysis indicate that aquifer conditions minimize the effects of sewage effluent contamination. Chloride and nitrate migration appears to be similar in the aquifer. Large-capacity wells were sampled to reflect regional conditions, and chemical hydrographs of chloride and nitrate were analyzed. The seasonal nature of these hydrographs patterns depend on total nitrogen in sewage effluent. Management alternatives are suggested to decrease nitrate pollution by sewage effluent.
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| 49 |
A Stochastic Analysis of Flows on Rillitto CreekBaran, N. E., Kisiel, C. C., Duckstein, L. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / In order to construct a simulation model for ephemeral streamflow and to examine in depth the problem of the worth of data for that model, measurements of the ephemeral streamflow of Rillitto creek, Tucson, were analyzed for the period 1933-1965. The simulation model was based on several hypotheses: (1) flow durations and their succeeding dry periods (time when no flow is present) are independent; (2) the distribution of the lengths of the dry periods and flows is stationary over a certain period of the year (summer); (3) stationary probability distributions for flow durations and for dry period lengths can be derived. A related problem was how to derive a simulation model for the total amount of flow (in acre-ft) within 1 flow period. Three variables were considered: flow duration (minutes), peak intensity of flow (cu ft/sec) and antecedent dry period-minutes (ADP). Because the assumption of variance constancy does not hold, a multiplicative regression model was used. Using an analysis of variance, which is described in detail, the worth of the 3 kinds of data were examined in relation to total flow. It was concluded that there are at least 5 times during the year when the flow intervals differ significantly, and the ADP is not important in determining flow volume because of the poison flow arrival rate in summer. Events occur at random and are not clustered as in summer, indicating that channel moisture does not differ much between flow events.
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| 50 |
Renovating Sewage Effluent by Ground-Water RechargeBouwer, Herman, Lance, J. C., Rice, R. C. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / Sewage effluent is commonly used for the irrigation of crops that are not consumed raw. Due to continued population growth in the Salt River Valley, Arizona, economic reuse of municipal waste waters is becoming essential. The salt river bed has about 3 ft of fine loamy sand underlain by sand and gravel layers to great depth and a groundwater table at about 10 ft depth. These conditions are very favorable for high-rate waste water reclamation by groundwater recharge. The activated sludge plant in phoenix will probably be discharging 250 mgd by the year 2000. At 4.5 ft average annual water use, this could irrigate about 70,000 acres, possibly more than agriculture will need at that time. A sewage effluent renovation pilot project was located about 1.5 miles from the plant. It contains 6 parallel recharge basins 20 to 700 ft each, spaced 20 ft apart. The basins were covered by grass, gravel or were left bare. Observation wells were installed at various locations in the area. Results indicated that infiltration rates were fastest in the grassy basins. Phosphate, nitrogen and median fecal coliform levels were all lower after this form of tertiary treatment. Practical details of the application of this water reclamation method in the Salt River Valley are outlined. Costs would be 5 dollars/af, less than 1/10 the equivalent costs of in-plant tertiary treatments.
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