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Showing 1 to 8 of 8 (0.083 seconds)Spelling suggestions: "subject:"hydrologic properties"" "subject:"hyrdrologic properties""
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Influence of microphytic crusts on selected soil physical and hydrologic properties in the Hartnet Draw, Capitol Reef National Park, Utah.Williams, John Dana 01 May 1993 (has links)
Microphytic crust influences on selected physical and hydrologic soil properties were examined at one location in Capitol Reef National Park, Utah. Designed experiments were conducted in a sandy loam soil where microphytic crusts were present without the concomitant development of confounding physical or chemical soil conditions. Three treatments were used for all experiments: control, chemically killed (microphytes killed but left in place), and scalped (microphytic crusts mechanically removed).
A portable wind tunnel was used to deter-nine if microphytic crusts contribute to soil stability and reduce the erosive effect of wind. Significantly lower threshold friction velocity and greater wind-entrained material were recorded in the scalped treatment than in the control or chemically killed treatments. These results are evidence that microphytic crusts significantly contribute to reducing the erosive force of wind at this site.
A dripper system was used in situ to determine if microphytic crusts influence effective saturated hydraulic conductivity. There were no significant differences among treatments. This result is evidence that microphytic crusts have a minimal influence, if any, on effective saturated hydraulic conductivity at this site.
Rainfall simulation was used to determine if microphytic crusts influence hydrologic properties of time to ponding, time to runoff, and infiltration capacity. Rainfall was simulated for 90 minutes after runoff began. Simulated rainfall also was used to determine if microphytic crusts influence interrill erosion. Time to ponding and time to runoff were significantly shorter in the control and chemically killed treatments than in the scalped treatment. However, infiltration capacity was not significantly different among treatments during any five-minute period within the 90 minutes that runoff occurred. Microphytic crusts apparently reduce initial entry of water into the soil profile; however, once infiltration has begun, they do not inhibit or enhance infiltration capacity at this site.
Interrill erosion was nearly constant from the control treatment throughout simulated rainfall events. Significantly greater interrill erosion occurred in the chemically killed treatment compared to control and scalped treatments. Interrill erosion in the scalped treatment was significantly greater than in the control treatment after 30 minutes and through 90 minutes. These results are evidence that microphytic crusts, when composed of living, undisturbed microphytes, resist the erosive effect of rainfall and contribute to the soil stability of this site.
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Color It EvaporationDvoracek, M. J. 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 / Evaporation is a major hydrologic process in arid and semiarid lands. A brief review of evaporation literature indicates that a unique parameter, color, is desirable. Artificially colored water was used in a west Texas experiment to monitor evaporation rate and to note the effect of color on evaporation. Artificially green water had a higher evaporation rate than sewage and runoff. Five different colored waters were studied from 1966 to 1970. Color seems to affect the amount of adsorbed radiation as well as the extent of black radiation. The trend for a higher daily rate of evaporation existed for colored waters except during periods of low air temperature. Seven graphs are presented to support these conclusions.
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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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Transmissivity Distribution in the Tucson Basin AquiferSupkow, D. J. 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 / The distribution of transmissivity within the Tucson basin aquifer, as determined by pumping tests and reviewed in the construction of a digital model of the aquifer, was not totally random in space. Data tended to be distributed normally or log-normally for biased samples of developed wells. A frequency distribution of transmissivity derived from a calibrated digital model is more nearly representative of the real world because the aquifer sample is without bias as the sample constitutes the entire aquifer. Geohydrologic setting, electric analog, and digital models of the basin are discussed. The theory of transmissivity distribution in an arid land alluvial aquifer is developed from Horton's laws of exponential relationship between stream order and drainage network parameters. It is hypothesized that there is an exponential relationship between transmissivity of an alluvial aquifer. A statistical study was made of values derived from the digital model to test the probability density function hypothesized for transmissivity. The mean value is a function of climate and drainage area. These hypotheses require further validation.
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Preliminary Investigations of the Hydrologic Properties of Diatremes in the Hopi Buttes, ArizonaScott, Kenneth C., Edmonds, R. J., Montgomery, E. L. 20 April 1974 (has links)
From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / Diatremes of Late Pliocene age in the Hopi Buttes area of Arizona are becoming increasingly important sources of groundwater to the Indian nations. These volcanic vent structures are prime sources of groundwater because sedimentary formations in the Hopi Buttes area yield only limited amounts of water or yield poor quality water. Diatremes act as traps for groundwater and some have yielded moderate amounts of good quality water to wells. Surface geologic investigations and analysis of drillers' logs indicate that structural relationships and diatreme lithology provide a means to project the hydrologic properties of the vent. Diatremes most suitable for groundwater development should have a diameter greater than one half mile, should contain volcanic tuff and breccia at its center, and should be fractured from collapse. Lava flows covering diatremes reduce recharge from sheet wash or from ephemeral stream flow. Data from geomagnetic and gravity surveys will be analyzed to determine its suitability for predicting subsurface size, shape, and lithology of the diatreme. The integration of geophysical and surface geologic data will reveal the total geometry of the structure enabling the most accurate appraisal of the hydrologic properties of the diatreme.
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Windbreaks May Increase Water Yield from the Grassland Islands in Arizona's Mixed Conifer ForestsThompson, J. R., Knipe, O. D., Johnson, Phil M. 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 / The general hydrologic characteristics, selected climatic factors, and soil properties of the high-elevation grasslands are compared to the surrounding forest. Evidence shows that water yield could be increased by 1-1/2 to 2 inches if snow could be held where it falls. It may be possible to establish tree windbreaks in the grassland by altering the microclimate during establishment, and introducing mycorrhiza with the planted seedlings. This conclusion is supported by good survival in a 2-year planting trial.
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Hydrologic Factors Affecting Groundwater Management for the City of Tucson, ArizonaJohnson, R. B. 15 April 1978 (has links)
From the Proceedings of the 1978 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 14-15, 1978, Flagstaff, Arizona / 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.
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Hydrology as a Science?Dvoracek, M. J., Evans, D. 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 / Experimental and historical development of the systematic study of water is briefly reviewed to prove hydrology a science. The hydrology program at the university of Arizona is outlined, and details of the course 'water and the environment' are expounded. This introductory course is intended for non-scientific oriented students at this southwestern university. A reading list is provided for the class, and scientifically designed laboratory experiments are developed. The first semester includes discussion of world water inventory; occurrence of water; hydrologic cycle; interaction of oceanography, meteorology, geology, biology, glaciology, geomorphology and soils; properties of water (physical, biological, chemical), and resources development. The second semester discusses municipal, industrial and agricultural water requirements, surface, ground, imported and effluent water resources management; water law; economic, legal, political, and social water resource planning; ecological impact; patterns of use; and survival of man. Mathematical problems are reviewed along with ecological orientation of students.
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