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Showing 1 to 9 of 9 (0.073 seconds)Spelling suggestions: "subject:"semiarid climate"" "subject:"emiarid climate""
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Recharging the Ogallala Formation Using Shallow HolesDvoracek, M. J., Peterson, S. H. 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 southern bed of the ogallala aquifer is hydrologically isolated from all outside areas of recharge, requiring local precipitation for all natural recharge. Current withdrawals are so much greater than natural recharge that it appears that artificial recharge affords the only means of establishing at least a pseudo-balance. A number of observation wells were drilled at Texas Tech University, and subsequently capped until recharge water became available. The initial recharge was 2.5 af over 12 days, at a rate of 120 gpm for about the first day, after which 60 gpm was relatively constant. Approximately 1 month later, 1.2 af were recharged over 3 days at rates ranging over 140-90 gpm. It became evident that a cavity was present at the bottom of the hole being recharged. On a later recharge occasion, the cavity seemed to have enlarged. During a period of 2 years more than 28 af of surface runoff water have been recharged through the shallow hole with increases in recharge rates for each subsequent recharge period. The nature of this phenomenon and the cavities are not understood. This may represent the long sought after answer to recharge of the aquifer, but much more extensive research needs to be done.
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Optimal Utilization of Playa Lake Water in IrrigationDvoracek, M. J., Roefs, T. 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 / Playa lakes usually occur in arid or semiarid regions where lands are flat and there is an absence of well-developed surface drainage nets. They are usually filled by surface runoff from highly erratic precipitation patterns. There are about 20,000 of them in the high plains of Texas and their volume of storage is an estimated 2.5-3 maf. As such, they represent a major underutilized water source. The major drawbacks to their utilization are high evaporation losses, questionable depth-area relations and the stochastic nature of the rainfall source. This paper assumes that the water is available and presents a dynamic programming model useful in determining the optimal utilization of the water for irrigation. If irrigation is the major use, its timing of application is of paramount importance. A deterministic dynamic programming model, utilizing the state variables of antecedent soil moisture and amount of available water, is presented, and provides the time and amount of irrigation required to maximize crop response. A better stochastic model is also presented which considers rainfall probability and resulting lake filling. The models are only first attempts and do not incorporate all possible variables.
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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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The Use of Chemical Hydrographs in Groundwater Quality StudiesSchmidt, Kenneth 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 / High nitrates in drinking water are significant in relation to an infant disease, methemoglobinemia, and the U.S. public health service has set a limit of 45 ppm for human consumption. This paper illustrates how chemical hydrographs were used in a study of nitrates in the groundwater of the Fresno-Clovis metropolitan area (F.C.M.A.) of semiarid central California. The area comprises about 145 square miles, with a population of 310,000. Urban water use is entirely derived from wells, whereas the surrounding agriculture relies on surface and ground water. In 1965, the California department of water resources noted nitrate concentrations in the F.C.M.A. were exceeding the safe limit. A number of sources of error in chemical analyses of water quality are noted. A measure of the accuracies of analyses and a method of double-checking anomalous results is furnished by plotting chemical hydrographs of individual wells. Seasonal changes in nitrate were consistent for many parts of the area, and were related to hydrogeologic factors and parameters directly affecting nitrification. Nitrate hydrographs were monitored by chloride hydrographs. The highest nitrate concentrations were in the shallower parts of the aquifer, and well deepening and changes in water level, pumping patterns and recharge rates complicated interpretations. However, the hydrographs helped to pinpoint the source of nitrate in areas where several possible sources were present.
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Increasing Forage Production on a Semiarid Rangeland WatershedTromble, J. M. 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 / Two native grass species, blue grama and sidecoats, were successfully seeded on a semiarid rangeland on the walnut gulch experimental watershed in southeastern Arizona. Optimum seeding dates selected were those within the time period most likely to receive precipitation, and grass stands were established in two successive years with average rainfall. Shrubs were killed by root-plowing at a depth of 14 inches, a procedure which was more than 95% successful in controlling sprouting shrubs. Forage production measurements taken on nm-28 sideoats and Vaughn sideoats showed a yield of 1,950 and 2,643 pounds of forage per acre, respectively, for the 2 years following the seeding, whereas untreated sites produced 23 and 25 pounds per acre of forage. Results indicate that success in establishing a stand of native grass is increased through use of existing hydrologic data.
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A Deterministic Model for Semi-Arid CatchmentsNnaji, S., Davis, D. R., Fogel, M. M. 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 / Semiarid environments exhibit certain hydrologic characteristics which must be taken into consideration for the effective modeling of the behavior of catchments in these areas. Convective storms, which cause most of the runoff, occur in high intensity and short duration during the summer months and are highly localized so that only a small portion of the catchment actually contributes flow to the storm hydrograph. Also, streams in semiarid catchments are ephemeral with flow occurring only about 1 percent of the time. This study attempts to develop a simple synthetic catchment model that reflects these features of the semiarid environment and for which (1) the simplifying assumptions do not preclude the inclusion of the important components of the runoff process, and (2) parameters of the equations representing the component processes have physical interpretation and are obtainable from basin characteristics so that the model may be applicable to ungaged sites. A reductionist approach is then applied in which the entire catchment is subdivided into a finite number of meshes and the various components of the runoff phenomenon are delineated within each mesh as independent functions of the catchment. Simplified forms of the hydrodynamic equations of flow are used to route flow generated from each mesh to obtain a complete hydrograph at the outlet point.
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Effects of Brush to Grass Conversion on the Hydrology and Erosion of a Semiarid Southwestern Rangeland WatershedSimanton, J. R., Osborn, H. B., Renard, K. G. 16 April 1977 (has links)
From the Proceedings of the 1977 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 15-16, 1977, Las Vegas, Nevada / Increased nutritional and economic demands for agricultural products have dictated the need for greater and more efficient use of western grass forage. Vegetation manipulation is the quickest and most economical means of increasing forage. However , the hydrologic effects must be taken into consideration before embarking on a large scale vegetation manipulated program. This study discusses the hydrologic and erosion changes measured from a 110-acre semiarid watershed which was converted from brush to grass by root plowing and seeding. Significant changes were observed in rainfall-runoff relationships as average summer runoff was considerably in excess of predictions. Sediment yield also varied, and both of these results were tied to the change in vegetative cover and post conversion rainfall conditions.
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Geomorphic Features Affecting Transmission Loss PotentialWallace, D. E., Lane, L. J. 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 / 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.
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Applicability of the Universal Soil Loss Equation to Semiarid Rangeland Conditions in the SouthwestRenard, K. G., Simanton, J. R., Osborn, H. B. 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 / An erosion prediction method that has recently received wide attention in the United States is the universal soil loss equation which is given as: a=rklscp. Where a = estimated soil loss (tons/acre/year), r = a rainfall factor, k = a soil erodibility factor, l = a slope length factor, s = a slope gradient factor, c = a cropping-management factor, and p = an erosion control practice factor. Data collected on the walnut gulch experimental watershed in southeastern Arizona were used to estimate these factors for semiarid rangeland conditions. The equation was then tested with data from watersheds of 108 and 372 acres. The predicted value of annual sediment yield was 1.29 tons/acre/year as compared with an average 1.64 tons/acre/year for 4 years of data for the 108-acre watershed, and a sediment yield of 0.39 tons/acre/year was predicted for the 372-acre watershed as compared with the measured value of 0.52 tons/acre/year. Although good agreement was noted between predicted and actual sediment yield, additional work is needed before the equation can be applied to other areas of the southwest.
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