Browsing by Subject "Aquifers"
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item Controls on and uses of hydrochemical and isotopic heterogeneity in the plateau aquifer system, contiguous aquifers, and associated surface water, Edwards Plateau region, Texas(2010-05) Nance, Hardie Seay, 1948-; Banner, Jay L.; Sharp, John Malcolm, 1944-; Kerans, Charles; Scanlon, Bridget R.; James, Eric W.; Mace, Robert E.Groundwater and surface water in the Edwards Plateau region exhibits spatial variability arising from mineral differences in aquifers and mixing of groundwaters with diverse flow paths and ages. Integration of basic hydrochemical and isotope data (⁸⁷Sr/⁸⁶Sr, [delta]¹⁸O, [delta]D, ¹⁴C, ³H) document that groundwaters in the Lower Cretaceous Edwards-Trinity (Plateau) aquifer system reflect intermixing of modern and Pleistocene recharge. Pleistocene recharge occurred under cooler paleo-climatic conditions, based on [delta]¹⁸O variance of 4.59%, and flow traversed sub-cropping Permian evaporite and Triassic strata under hydraulic conditions that promoted upward flow into the Plateau system. Recharge areas may have been in topographically elevated areas in New Mexico that no longer are connected with the Plateau. Present distribution of groundwaters with higher SO₄/Cl values occurring beneath topographic divides on the Plateau suggests that modern recharge occurs preferentially in losing-stream networks and is inhibited on divides by low-permeability soils. Relationships between ¹⁴C, tritium, [delta]¹³C, and Mg/Ca values confirm that effectively younger groundwaters occur beneath the upper parts of drainage networks, but down slope of divides. Thus, groundwater-age and hydrochemical data suggest that recharge preferentially occurs in the upper parts of drainage networks. Correlations between groundwater relative age and Mg/Ca enable estimation of the proportion of modern recharge at specific well locations based on Mg/Ca values and enables estimating local absolute recharge rates from regional-scale recharge estimates obtained from regional flow models. The Upper Colorado River bounds the northern and northeastern margin of the Plateau system and shows systematic chemical evolution along its flow path, including decreasing salinity and increasing SO₄/Cl values. The stream can be conceptually divided into three segments that each reflect groundwater inputs from five hydrochemically distinct intervals: 1) deep Permian and Pennsylvanian reservoirs similar to those that produce hydrocarbons in the region; 2) Upper Permian halite (Salado Formation); 3) the Triassic siliciclastic aquifer (Dockum Group); 4) the sulfate-evaporite-bearing Permian system (Ochoan, Guadalupian, and Leonardian Series); and 5) the Plateau aquifer system. Conservative mixing models suggest that any aquifer that the river is traversing at a specific location contributes a distinct hydrochemical signature, but the dominant contribution is from the Plateau system.Item Evaluation of the aquifer storage and recovery pilot project in Liwa area, Emirate of Abu Dhabi, UAE(2010-12) Khezri, Solaleh; Charbeneau, Randall J.; Herrmann, RolfEmirate of Abu Dhabi is located in an arid region, where the main source of fresh water is desalination plants. The vulnerability of desalination plants renders planning for an alternative source of freshwater essential. In this study the feasibility of aquifer storage and recovery in the Liwa area, in Emirate of Abu Dhabi, United Arab Emirates was investigated. Based on operational data collected from the pilot project, the model was set up and calibrated. The calibrated model was used to study the affect of various operational parameters, namely storage duration, pumping rate, screen location, multiple cycle operation and periodic recharge, as well as some aquifer characteristics factors: dispersion and salinity profile. This study can be utilized to optimize the operation of the Liwa ASR project.Item Intra-aquifer characterization and potential management impacts : Trinity Aquifer, Central Texas.(2012-08-08) Diehl, Michelle Lynn.; Yelderman, Joe C.; Geology.; Baylor University. Dept. of Geology.Management of groundwater resources is a critical issue in Texas and groundwater conservation districts have been given this responsibility. While large databases containing well characteristics are available for use from state agencies, they have not been organized for spatial correlation and analysis. As a new entity (2007), the Southern Trinity Groundwater Conservation District (STGCD) is faced with developing and analyzing such data. An unusual challenge for the STGCD is managing groundwater production among wells completed either solely in the upper aquifer (Hensell unit), lower aquifer (Hosston unit), or dually completed in both units of the Trinity Aquifer. The goals of this project were to develop a spatially-based well data set that can be used for management decisions. Results include a report to the STGCD with a database, contour maps for different aquifer characteristics, and well hydraulics analysis.Item Intra-meander groundwater-surface water interactions in a losing experimental stream(2010-08) Nowinski, John David; Cardenas, Meinhard Bayani, 1977-; Sharp, John M.; Bennett, Philip C.Groundwater-surface water interactions between streams and shallow alluvial aquifers can significantly affect their thermal and chemical regimes and thus are critical for effective management of water resources and riparian ecosystems. Of particular significance is the hyporheic zone, an area delineated by subsurface flow paths that begin and end in surface water bodies. Although detailed work has examined hyporheic flow in the vertical dimension, some studies have suggested that the drop in a stream’s elevation as it flows downstream can laterally extend the hyporheic zone. This study examines intra-meander hyporheic flow using extensive field measurements in a full-scale experimental stream-aquifer system. Synoptic head measurements from 2008 and 2009 and a lithium tracer test were conducted to determine the extent and nature of hyporheic flow within the meander. Permeability was measured and sediment cores were analyzed from 2008 to 2009 to assess aquifer properties. Finally, transient head and temperature measurements were collected during flooding events to assess the sensitivity of intra-meander hyporheic flow and temperature to stream discharge. Results verify that hyporheic flow through meanders occurs, but show that it is sensitive to whether a stream is gaining or losing water to the subsurface overall. In addition, permeability and core grain size results indicate moderate heterogeneity in permeability can occur in aquifers composed of relatively uniform sediment. Results also demonstrate that permeability in alluvial aquifers can evolve through time. Such evolution may be driven by groundwater flow, which transports fine particles from areas where porosity and permeability are relatively high and deposits them where they are relatively low, thus creating a positive feedback loop. Finally, measurements during flooding indicate that steady-state hyporheic flow and the thermal regime within the aquifer are largely insensitive to stream discharge. Together, these results expand upon previous field studies of intra-meander hyporheic flow and verify previous modeling work, although they demonstrate a level of complexity within these systems that should be considered in future work.Item Issues of engineering and geochemistry in the sequestration of carbon dioxide in geological formations-saline aquifers(Texas Tech University, 2004-05) Garcia-Orrego, Gloria StellaDynamic tests were conducted to evaluate the feasibility of sequestering carbon dioxide (CO2) in a carbonate dolomite reservoir. Two injection rates, 5.696E-06 cubic feet/ min (0.1613 cc/min (20 pore volumes)) and 3.467E-05 cubic feet/min (0.982 cc/min (120 pore volumes)) were tested to observe changes in petrophysical parameters, particularly permeability and porosity at each rate. The low injection rate allowed the evaluation of the effect on the bulk of the reservoir. And the high injection rate to evaluate the effect of dissolution on the face of the formation. The tests were carried out at reservoir simulated conditions (2000 psia (140.64 atm) and 150°F (65.5°C)). San Andres dolomite formation cores from wells 744 and 745 drilled in the Levelland Field were used for this study. The dolomite formation is cemented by calcite and it has a high content of anhydrite. The formation brine of the Permian Basin was used to inject the cores. This brine has sodium 18,000 mg/L, chlorine 46,200 mg/L, calcium 6000 mg/L, sulfate 4880 mg/L, magnesium 1820 mg/L and potassium 1510 mg/L. The injection of low pore volumes was found to reduce the permeability by about 50%, and the pore volume and porosity by about 25%. The total equilibrium magnetization (Mo) from NMR T2 distribution is decreased by about 17%, indicating substantial reduction in porosity and permeability. The small pore sizes (bulk volume irreducible-BVI) increased on average by about 70% and the large pore sized (free fluid index-FFl) decreased by about 24%. The injection of high pore volume CO2 showed a slight increase in the petrophysical properties, permeability and porosity. The total equilibrium magnetization, B VI, and FFI did not present remarkable change. At the onset of this research, it was still uncertain how the interaction between CO2 and formation brine affects the geochemistry of the reservoir. Therefore, several static tests under supercritical conditions (1070 psia (78 atm) and 88°F (31.TC)) and under reservoir conditions with and without rock samples were carried out. After running the static tests for seven days, a precipitate formed from the brine after reaction with CO2 was obtained. The precipitate was analyzed using scanning transmission electron microscopy (STEM) to identify the specimen structure and to obtain a chemical analysis using an energy-dispersive spectrometry (EDS). Also, X-ray diffraction method (XRD) was used to identify the new minerals formed as a consequence of the interaction between CO2 and formation brine. Observations indicate that the precipitated is formed primarily by calcite, gypsum, halite and other mineral salts. On the basis of the previous observations, it can be concluded that at low pore volumes, a compact dissolution of anhydrite took place, followed by deposition of material dissolved from the rock and/or precipitation of the salt dissolved from brine. Consequently, the permeability and porosity were significantly reduced. In contrast, these effects in high pore volumes injected were masked by high dissolution of the anhydrite, leading to the formation of new flow paths (similar to wormholing in acidizing operation), and an increase in permeability and porosity. However, the increase in petrophysical properties could be offset by a reduction caused by precipitation of material, either from the dissolved salts in the brine or from the dissolved rock. Another objective of this investigation was to determine the amount of shale in a sandstone reservoir. This is an important issue for evaluating the storage capacity of given aquifer/ reservoir as a candidate for CO2 sequestration. A non-linear relationship of gamma ray index to volume of shale has been derived in a self-consistent formulation of emission and attenuation of gamma rays within the shale-sand composite. The technique to produce the derivation includes the self-shielding attenuation effects that occur at higher volumes of the shale gamma ray emitters. The effects of porosity and grain density of the constituents are included in the relationship of shale volume to gamma ray index. The new approach is applied to log data from the San Jorge Basin in Argentina.Item Modeling tracers and contaminant flux in heterogeneous aquifers(2003) Jayanti, Shekhar; Pope, G. A.; Bryant, Steven L.Item The role of aquifer storage and recovery (ASR) in sustainbility(2010-12) AlRukaibi, Duaij; McKinney, Daene C.; Maidment, DavidKuwait is an arid country situated at the head of the Arabian Gulf and its water resources can be classified into three significant types: (1) natural (groundwater) and (2) artificial (desalinated sea water and treated wastewater). In the absence of surface water bodies, groundwater constitutes the most important natural water resource in Kuwait with TDS [less than or equal to]10000 mg/L in central and south Kuwait. Only in the north can one find fresh water lenses. Brackish groundwater are used for irrigation, landscaping, construction work, non-potable use in households and mixing with desalinated water up to 10%, to make it potable. The occurrence of usable groundwater is limited to the Kuwait Group and Dammam Formation. Due to over-pumping of groundwater over the last few years, the levels and quality of groundwater are deteriorating. Kuwait is described as the poorest country in terms of water availability (UN World Water-2003). The current rates of water consumption are very high, with 459.6 L/C/d and almost 91 L/C/d for fresh and brackish water, respectively. The water budget of the water resources, represented as percentages is 59% from desalination sea water plants, 32% from groundwater with the possibility to increase the use of this resource and 9% from waste water reuse plants. Although Kuwait does not have any surface water, but it depends on technology to produce water recourses to meet the demand. The best solution for solve the issues of declining water levels and increasing salinity is artificial recharge. Artificial recharge has been applied in Kuwait in different groundwater fields since the 1980s. In addition, the available surface storage capacity of 11.7 Mm³ freshwater is sufficient to meet demand for about 7 days. So, Aquifer storage and recovery (ASR) can be used to store the water in aquifers instead of surface storage. ASR entails storing water in aquifers during wet times and recovering the water from the same well during drought times. Surface storage needs construction resources and vast land. In contrast, storing water in aquifer storage does not need that and it can decrease salinity and keep the water table constant. The water availability for artificial recharge can come from desalination and wastewater plant. The capacity and production of desalination plants are 1.425Mm³/day (525.125Mm³/yr) and 1.31Mm³/day (478.15 Mm³/yr), respectively from 5 stations. The excess capacity is 115000 m³ per day and could reach 290000 m³ per day in the winter season. Wastewater treatment plants produce from 3 plants around 0.337 Mm³/day (123.342 Mm³/yr) and the newest plant (operating by RO system) produces 0.32 Mm³/day (117.12 Mm³/yr) and will reach 0.643 Mm³/day (235.338 Mm³/yr) in 2015. The water produced from wastewater treatment plants has good quality and can be used for irrigation, greening enhancement, landscaping, recreation (artificial river and lakes) and artificial recharge. Also, using water treated for artificial recharge will improve the quality of injected water that has been successfully treated with soil aquifer treatment technology. Groundwater pumping is 200 Mm³ annually and is likely to reach 280 Mm³ in the future. This research will explore and create a database for water resource by GIS software using its tool to select and display suitable areas for ASR operation. Artificial recharge in Kuwait has used the concept of injection and recovery of water in one cycle, while here we will apply the multi-cycle concept to avoid increasing the piezometric head and clogging the porous media. The injected water will be from wastewater treatment plants with a TDS content of less 500 ppm and the TDS of recovered water in each well less than 1500 ppm. Moreover, there are criteria for selecting a domain for artificial recharge, for example, moderate transmissivity, The TDS of the aquifer should not exceed 5000 ppm, and the horizontal and vertical hydraulic gradient should be as small as possible and close to the stations suppler and demand center. The success of artificial recharge will depend on the recovery efficiency (RE) in every cycle which will increase if artificial recharge done in the correct way. The RE increases with a decrease in time between the stopping of injection and the starting of the recovery operation. Aquifer storage and recovery can play an important role as sustainability tool to resolve water resource problems, improving water quality, better than surface water storage since it minimizes construction of new infrastructure and uses that cost to initiate new desalination or waste water plants. At the end of this research we will have demonstrated the concept of the process of ASR including the volume and time for injection and recovery of water in multi-cycles and in different suitable sites.Item The development of a computerized procedure to determine aquifer parameters(Texas Tech University, 1972-12) Knowles, Tommy R.Not availableItem The frequency of significant recharge to the Ogallala aquifer from playa lakes(Texas Tech University, 1985-12) Oppel, Sharon E.The objective of this research is to establish the frequency of significant amounts of natural recharge occurring from playa lakes following large precipitation events, and determines if the quantity is enough to discontinue artificial recharge studies. Previous investigations of recharge, as well as the Soil Conservation Service method of computing runoff, are reviewed in Chapter 2. The method used to compute runoff from historical rainfall events is described in Chapter 3. The results of the analysis are presented in Chapter 4. Chapter 5 contains the conclusions, some observations regarding their importance, and recommendations resulting from the overall study.Item The Texas High Plains Aquifer system: modeling and projections for the southern region(Texas Tech University, 1996-05) Dorman, Troy M.The Texas High Plains is a region buih on irrigated agriculture. In 1989, over 65 percent of the total irrigated acreage in Texas, or 3.95 million acres, was located on the High Plains (Ashworth & Peckham 1993). Water for irrigation and many domestic supplies is pumped from the High Plains Aquifer System, with most coming from the Ogallala Aquifer. During the past five decades, water levels in the Ogallala have dropped dramatically because pumpage is much greater than recharge. Although the aquifer is large, it will eventually be depleted unless current withdrawal rates are decreased. The reductions could be accomplished either through voluntary conservation or government regulations. However, groundwater in Texas is presently the property of the landowner and cannot be controlled by state regulations. The solution to this problem lies in finding amenable methods to reduce pumpage and developing alternative sources of water for the region.