1,721,010 research outputs found
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Flow model for the Bingham cienega area, San Pedro river basin, Arizona: a management and restoration tool
No full textA finite element groundwater flow model was used to support a hydrologic assessment for a study area in the Lower San Pedro River Basin which contains the Bingham Cienega. Consolidated sedimentary rocks associated with an extension of the Catalina Core Complex truncate the floodplain aquifer system in the study area. The elevated water table produced by this "hardrock" results in spring discharge at the cienega and a locally gaining reach of the San Pedro River. The steady -state model suggests that recharge (and discharge) components for the floodplain aquifer sum to 3.10 cfs. Mountain front recharge, underflow, and stream leakage are the primary recharge mechanisms, while stream leakage, evapotranspiration, spring flow, and underflow out are sources for groundwater discharge. A steady -oscillatory model was used to account for seasonal periodicity in the system's boundary conditions. Monthly variation in the evapotranspiration rate was offset primarily by storage changes in the aquifer. Due to a lack of measured hydrologic data within the study area, results from the model simulations are only preliminary. Model development and the subsequent sensitivity analyses have provided insight into what type of data needs to be collected. Head measurements are most needed in the area just downstream from Bingham Cienega. The mountain front recharge and evapotranspiration rates are shown to be highly sensitive parameters in the model; improved estimation of these values would be helpful. Spring discharge would be a valuable calibration tool if it could be accurately measured. A more extensive record of stream baseflow in the San Pedro River should be established. After more hydrologic data is collected, the model could be recalibrated so as to better represent the system. Eventually, this tool may be used in direct support of management and/or restoration decisions.Research and development for this project was funded in part by the Arizona
Chapter of The Nature Conservancy. The views and conclusions reported are those of the
author and are not necessarily shared by The Nature Conservancy.
We would like to give special thanks to Robert Mac Nish, Kate Baird and Kevin
Lansey for their thoughtful comments on this document.This title from the Hydrology & Water Resources Technical Reports collection is made available by the Department of Hydrology & Atmospheric Sciences and the University Libraries, University of Arizona. If you have questions about titles in this collection, please contact [email protected]
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Application of a ground-water flow model to the Mesilla Basin, New Mexico and Texas
No full textResolution of litigation between El Paso, Texas, and New Mexico over the water resources of the Mesilla Basin prompted a ground-water modeling study to address the common concerns of both parties. Participants requested development of a model which eventually could be used to simulate the ground-water and surface-water system's response to lining a portion of the canal system and to changes in pumping stresses within the Mesilla Basin. An existing U.S. Geological Survey ground-water flow simulation (Frenzel and Kaehler, 1990; Frenzel, 1992) was updated and revised through modification and incorporation of a new Streamflow-Routing (Prudic, 1989) package for use with MODFLOW (a three-dimensional finite-difference groundwater flow model; McDonald and Harbaugh, 1988). The modified Streamflow-Routing package was used to simulate the complex Mesilla Valley river, canal, and drain system. Updating also included incorporation of information on pumping stresses; canal, river, and drain parameters; Mesilla Valley boundary fluxes; and stream/aquifer interactions
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Preliminary steady-state modeling calibrations of Tucson Water's Central Well Field flow model Tucson Basin, southeastern Arizona
No full textThis study reviews the assumptions, the assembled data, and the considerations involved in calibrating a preliminary steady-state model of the City of Tucson's Central Well Field. This study introduces a hydrostratigraphic characterization of basin sediments and develops a new set of aquifer parameter data. The results of two preliminary steady-state calibrations are presented based on assumed steady-state conditions in the early 1900s and quasi-steady-state conditions in 1940. Transient stresses over a 50-year period are imposed onto the results of the 1940 steady-state simulation to identify major deficiencies in the preliminary calibration
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Modeling of groundwater flow and surface/groundwater interaction for upper Cienega Creek Basin
No full textThe modular three-dimensional finite-difference groundwater flow model (MODFLOW) was used to study the hydrology of Upper Cienega Creek. The geological and hydrological characteristics of the basin indicate that the groundwater is contained in an unconfined aquifer. The study focuses on the interaction between groundwater and surface water in Upper Cienega Creek Basin and the surrounding basins (Sonoita and Bobocamari). The steady state analysis simulated the predevelopment conditions of the aquifer, and the transient state analysis, conducted between 1989 and 2002, predicted the response of the aquifer to future stresses. The location of pumpage and the volume of water pumped during the entire transient period resulted in a minimum reduction (1%) of the Cienega Creek stream flow. However, a drawdown of 200 ft located in Sonoita and Elgin area was predicted in the transient simulation. Capture calculations show that the reduction in evapotranspiratiou partially balanced the volume of water lost as result of pumping.Digitized from paper copies provided by the Department of Hydrology & Atmospheric Sciences
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A GEOCHEMICAL APPROACH TO DETERMINE GROUND-WATER FLOW PATTERNS IN THE SIERRA VISTA BASIN, ARIZONA, WITH SPECIAL EMPHASIS ON GROUND-WATER/SURFACE-WATER INTERACTION
No full textWater quality in the Sierra Vista Ground-Water Basin is of extreme importance due to the basin's unique ecosystem and predicted future population growth. Portions of the Upper San Pedro River, flowing through the Sierra Vista Basin, contain some of the few remaining perennial streamflows in the southwest. Baseflow in the perennial reaches of the river are maintained almost entirely by the regional and floodplain aquifer systems. A population increase is predicted for the Sierra Vista Basin, and an impact on groundwater quality and availability can be expected. Due to the closely linked hydrologic systems within the basin, contamination or depletion of the regional aquifer could have direct implications for the San Pedro River. Water samples were collected within the study area from the regional and floodplain aquifers, the San Pedro River, and a bedrock spring in the Huachuca Mountains. Samples were analyzed for field parameters, major-ions, and stable isotopes to describe the main chemical characteristics of the hydrologic systems within the basin. Analysis of regional aquifer geochemistry indicates a ground-water system strongly controlled by calcite precipitation. Specific conductance, deuterium and oxygen-18 values indicate a mixing of regional-aquifer ground water and San Pedro River surface water within the floodplain aquifer. Estimates of inflow to perennial reaches of the floodplain aquifer from the regional aquifer vary from 50 to 80%, depending on location. Inflow to the San Pedro River at Charleston from the regional aquifer is estimated to be about 50 to 70% of the stream discharge.Digitized from a paper copy provided by the Department of Hydrology and Water Resources
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A groundwater monitoring program based upon a groundwater flow model
No full textThis thesis concerns a groundwater modeling study south of Tucson, Arizona where 10,000 acre-feet of Central Arizona Project water may be annually recharged. South and west of the site are the Santa Cruz River and the Tohono O'odham Indian Nation. Well fields to the immediate east, west and south supply water to the City of Tucson and to farming and copper mining corporations. Operation of the corporate well fields has lead to a water table depression just west of the site. The purpose of the model is to understand of the most probable groundwater flow regime in light of aquifer recharging and groundwater mining. The model serves to compare groundwater conditions with previous investigations. Lack of data precluded the construction of a model capable of producing reliable predictive results. Hydrogeologic data gathered provide a foundation for future modeling studies. Insufficient data serve as indicators of present groundwater monitoring deficiencies
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Design of wellfield and recharge operations in forebay area of San Bernardino basin, California
No full textEast Valley Water District is located in San Bernardino, California which is approximately 50 miles east of Los Angeles. In order to meet future water demands, East Valley Water District plans to increase recharge activities in the forebay area of the San Bernardino groundwater basin and expand wellfield operations immediately downgradient. Three possible recharge and wellfield designs were under consideration with annual recharge rates increasing 10,000 to 20,000 acre-feet/year in the Santa Ana spreading basins. Approximately four to five new production wells pumping an equal quantity of groundwater have been proposed. A two-dimensional finite element groundwater flow model was constructed and calibrated to reproduce historical water level data for the year 1945. They calibrated model was applied to simulate the hydrologic effects of each of the three designs over a ten-year period
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Hydrologic assessment and computer model application in the Upper Santa Cruz River Basin, Santa Cruz County, Arizona
No full textA two-phase study of the Upper Santa Cruz River Basin consisting of a hydrologic assessment and the application of a computer model to the area is presented. Groundwater occurs in Older and Younger Alluvium units, is held under unconfined conditions, and is of good quality. The Finite-Difference Three-Dimensional Groundwater Flow Model (MODFLOW) is applied to the study area in order to simulate the hydrologic system. A water budget and conceptual model is developed to aid in model input and calibration. A steady-state analysis for the system is performed for 1965 in order to calibrate model parameters and produce initial conditions for the transient analysis. A transient analysis is performed to verify model response over the period 1965-1980 in which stresses to the system are changing. Model-produced trends and water levels are consistent with observed data, indicating the model's utility for predictive analysis of the system
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Statistical analysis to identify trends in water quality in the Hueco Bolson, near El Paso, Texas
No full textFour parameters were examined to detect changes in ground-water quality in the Hueco bolson near El Paso, Texas. Sulfate (SO4), chloride (CL), nitrate (NO3), total dissolved solids (TDS) and pumpage data from 148 wells from 1970 through 1985 were used in the investigation. Regression analyses and contouring were used to determine if changes occurred with time, pumpage, depth or space. Results from the statistical tests indicate CL and TDS increase with time and average values of CL, NO3 and TDS increase with total pumpage. Contour maps of the 4 constituents for the years 1970, 1975, 1980 and 1985 show a spatial increase in concentration. Contour maps of the regression coefficients pinpoint areas where the concentrations of the parameters are increasing with time. Degradation of the water quality appears to be due to several sources: urban runoff; leakage of saline water; lateral intrusion of saline water; and industrial pollution.hydrology collectio
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Modeling of ground-water flow and surface water/ground-water interactions of the San Pedro River Basin, Cochise County, Arizona
No full textGround-water exploitation in the Upper San Pedro Basin has produced the formation of a cone of depression around the Sierra Vista-Fort Huachuca area. A portion of the mountain front recharge that otherwise would reach the San Pedro River is being intercepted by pumping, and portions of baseflow are being captured by pumping. The purpose of this study is to construct a simulation model capable of simulating the ground-water system as well as the ground-water-surface water interactions. The flow simulation was done by a three-dimensional, finite-difference ground-water flow model (MODFLOW) that incorporates a new stream-aquifer interaction package. Steady state simulations were performed to represent mean annual conditions. Transient simulations cover a 48 year period, starting in 1940 and ending in 1988. A sensitivity analysis of the steady state model was also performed
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