Browsing by Author "Ronayne, Michael, advisor"
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Item Open Access A method using drawdown derivatives to estimate aquifer properties near active groundwater production well fields(Colorado State University. Libraries, 2014) Lewis, Alan, author; Ronayne, Michael, advisor; Sale, Tom, committee member; Sanford, William, committee memberThis thesis describes the development of a new inverse modeling approach to estimate aquifer properties in the vicinity of continuously-pumped well fields. The specific emphasis is on deep bedrock aquifers where monitoring well installation is often not practicable due to high drilling costs. In these settings, water levels from groundwater production wells offer a transient dataset that can be used to estimate aquifer properties. Well interference effects, if detectable at neighboring production wells, allow for an interrogated aquifer volume that is larger (and therefore more representative at the well field scale) when compared to single well hydraulic tests. The parameter estimation method utilizes drawdown derivatives to estimate the aquifer transmissivity and storativity. The forward model consists of an initial water level (or a recoverable water level drift function), an analytical solution for aquifer drawdown, and a correction term for well loss. The aquifer drawdown component is based on superposition of the Theis solution, although other analytical solutions are also applicable. The observed dataset was judiciously trimmed to reduce computer run-time while retaining enough points to adequately characterize aquifer and well parameters. By limiting observation points to special domains, the calculated drawdown and observed well water level derivatives with respect to time are independent of well loss, and therefore the transmissivity and storativity can be estimated without knowledge of the recoverable water level or loss coefficient for individual pumping wells. Aquifer properties in the forward model were estimated by minimizing the difference between the modeled and observed drawdown derivatives. The parameter estimation method is tested using hourly water level and pumping data from municipal well fields producing groundwater from sandstone aquifers of the Denver Basin. Data collected over a seven-year period from two distinct well fields, one operating in the Denver aquifer and another operating in the Arapahoe aquifer, are considered. The estimated transmissivities are 30.0 m2/d and 46.5 m2/d for the Denver and Arapahoe aquifers, respectively, whereas the storativities are 4.7×10-4 and 2.0×10-4, respectively. These estimates are within the range of previously reported values, indicating that production well data can be used to derive reasonable aquifer properties. A separate synthetic aquifer test case was considered to further test the parameter estimation methodology, as well as to evaluate the appearance of Theis-like response behavior at the wells. Synthetic water levels were generated using a numerical model with geostatistically-simulated heterogeneity that is characteristic of the Denver Basin (sandstone bodies separated by less permeable inter-bedded siltstone and shale). Analysis of the synthetic water levels revealed meaningful hydraulic properties; the effective hydraulic conductivity (best-fit transmissivity divided by the modeled aquifer thickness) was slightly higher than the geometric mean hydraulic conductivity of the heterogeneous field. In addition to aquifer properties, observed water level data were used to estimate the well-loss coefficient and recoverable water level for individual pumping wells. Loss coefficients obtained for wells in the Denver Basin indicate that this mechanism (head losses due to turbulence around the well screen) may contribute between 20 and 150 m of the total drawdown (based on a pumping rate of 1500 m3/d) commonly observed in these wells. The recoverable water level at each well, when fit with a linear drift function, provides a means of investigating the prevailing trend in aquifer heads due to other regional influences outside the modeled well field.Item Open Access Characterization of peat soil hydraulic conductivity and its dependence on vegetation type in mountain wetlands(Colorado State University. Libraries, 2015) Crockett, Audrey, author; Ronayne, Michael, advisor; Cooper, David, committee member; Sanford, William, committee memberPeat-forming wetlands enhance biodiversity and provide carbon storage in mountain environments. Persistence of these wetlands requires sustained water inflows. Reduced or altered inflows associated with climate change could lower the water table, potentially resulting in peat oxidation and carbon release to the atmosphere, as well as the loss of wetland plant and animal species. An understanding of the hydrology and site hydraulic properties is necessary to manage mountain wetlands and assess their vulnerability to climate change. This study characterized the hydraulic conductivity of wetland peat soils in Rocky Mountain National Park (RMNP). Peat-forming wetlands in RMNP are classified as fens because their main source of water is groundwater. Fens in RMNP contain a broad range of vegetation. Dominant vegetation type is one factor that may influence peat hydraulic conductivity, so the fens in this study were divided based on dominant vegetation type. The three vegetation classifications used were “large sedge,” “small sedge,” and “heterogeneous,” indicating that the fens were dominated by large sedges (mainly Carex); small sedges (Eleocharis quinqueflora); or a mixture of woody plants, sedges, and moss; respectively. In this study, field measurements were combined with a numerical model and parameter estimation scheme to produce estimates of hydraulic conductivity with a high degree of confidence. Single-ring infiltration tests were performed in the field. A numerical model was constructed, and a parameter estimation scheme was used to find the hydraulic conductivity that best reproduced the results of the single-ring infiltration test. The fens dominated by small sedges have significantly lower hydraulic conductivity than the fens dominated by large sedges or heterogeneous vegetation. Fens which have relatively high hydraulic conductivity (those dominated by large sedges or a heterogeneous mixture of plants) may be especially at risk of draining under changing climate regimes. Small-sedge fens may be more likely to maintain a high water table due to their low hydraulic conductivity.Item Open Access Controls on groundwater-surface water interaction in a glacial valley, northern Colorado(Colorado State University. Libraries, 2022) Doebley, Valerie, author; Ronayne, Michael, advisor; McGrath, Daniel, committee member; Kampf, Stephanie, committee memberIn the last few decades, scientists determined that groundwater discharge may supply a significant portion of streamflow in mountain watersheds. However, difficulties with access and drilling typically limit the use of monitoring wells to study groundwater in high-elevation, mountainous catchments. The recent installation of two 10-meter-deep monitoring wells plus several riparian wells along the South Fork of the Cache la Poudre River at the Colorado State University Mountain Campus provided an opportunity for a unique hydrogeological study at a mountainous site. Data from these wells combined with numerical groundwater modeling helped quantitively and qualitatively characterize groundwater-surface water exchange along a ~2.7-km study reach. Analyses reveal complex temporal and spatial variation of gaining and losing stream conditions within the study reach. First, well water level elevations and groundwater modeling results indicate that the South Fork is generally gaining in the upper portion of the valley and losing near the downstream end. We suggest that valley geometry and channel planform influence the spatial differences in groundwater-surface water exchange along the study reach. Second, streamflow differencing and modeling results suggest that the study reach changes between overall gaining and overall losing stream conditions multiple times between May and October. We suggest that these temporal variations in groundwater-surface water exchange are driven by seasonal changes in surface water contributions to streamflow and evapotranspiration. Third, stable isotope (δ2H, δ18O) analyses and groundwater modeling results suggest that localized recharge from moraine ponds and stream leakage are important sources of aquifer recharge. These results indicate that groundwater and surface water at the Mountain Campus are highly interdependent, and that any disturbances that impact surface water contributions to streamflow may ultimately impact the groundwater contributions as well.Item Open Access Coupled analytical modeling of water level dynamics and energy use for operational well fields in the Denver Basin aquifers(Colorado State University. Libraries, 2013) Davis, Jennifer Anne, author; Ronayne, Michael, advisor; Sale, Thomas, advisor; Sanford, William, committee member; Bau, Domenico, committee memberThe South Metro Denver area in Colorado has been experiencing rapid growth in recent years and many municipalities in this region rely on the groundwater resources available in the Denver Basin as their chief water supply. As the population continues to increase, municipal water demands must be met with a sustainable approach. The Denver Basin aquifer system consists of four major aquifers that are composed of interbedded layers of sandstones, siltstones, and shales. The aquifers receive limited annual recharge and consequently the groundwater within them has the potential to be depleted. Declining water levels associated with groundwater depletion, interference between pumping wells, and fouling of wells is leading to losses in well productivity. Furthermore, declining water levels translates to higher electrical energy costs associated with water production. Regional-scale numerical models developed for the Denver Basin aquifer system do not capture the local-scale drawdown about pumping wells, which is needed to effectively manage existing groundwater well fields. This research project utilizes production well data from the town of Castle Rock, Colorado to test the merits of using a Theis based approach to model water levels about production wells in the Denver and Arapahoe aquifers in Castle Rock. The model applies superposition of the Theis solution throughout both space and time to resolve the combined effects of pumping from multiple wells. This research demonstrated that the analytical method can be successfully applied as a predictor of continuous water levels at pumping wells. In addition, the analytical model provided a novel method for estimating aquifer properties using data from an operational well field, and it contributed a better understanding of the cross-well interferences that increase well drawdown. The model results were used to evaluate alternative pumping scenarios intended to reduce electrical energy costs associated with water production and increase sustainable yields from these aquifers. The alternative pumping scenarios achieved a net reduction in energy consumption ranging from 1.62% to 13.0% and led to a stronger conceptual understanding of how each aquifer responds to varying pumping conditions. This research demonstrates that the analytical solution modeling approach may be beneficial for application to many other projects involving groundwater supply management and optimization.Item Open Access Coupled continuum pipe-flow modeling of Karst groundwater flow in the Madison limestone aquifer, South Dakota(Colorado State University. Libraries, 2013) Saller, Stephen Paul, author; Ronayne, Michael, advisor; Sale, Thomas, committee member; Egenhoff, Sven, committee memberKarst carbonate aquifers are traditionally difficult to model due to extreme permeability heterogeneities and non-Darcian flow. New modeling techniques and test applications are needed to improve simulation capabilities for these complex groundwater systems. This study evaluates the coupled continuum pipe-flow framework for modeling groundwater flow in the Madison aquifer near Rapid City, South Dakota. The Madison carbonate formation is an important source of groundwater underlying Rapid City. An existing equivalent porous medium (EPM) groundwater model of the Madison aquifer was modified to include pipe networks representing conduits. In the EPM model, karstified portions of the aquifer are modeled using high hydraulic conductivity zones. This study hypothesized that the inclusion of conduits would allow for a simpler hydraulic conductivity distribution and would improve modeled fits to available data from a 10-year monitoring period. Conduit networks were iteratively fit into the model based upon available environmental and dye tracer test data that approximated major karst pathways. Transient simulation results were evaluated using observation well hydraulic heads and estimated springflow data. In a comparison to the EPM model, the new modeling results show an improved fit to the majority of observation well targets, and negligible impact to springflow data. The flow dynamics of the aquifer model were significantly altered, with the conduit networks acting as gaining or losing subsurface features, behaving as regional sinks during dry periods and flowpath heterogeneities during wet periods. The results of this study demonstrate that the coupled continuum pipe-flow modeling method is viable for use within large regional aquifer models.Item Open Access Effects of long-term pumping on recharge processes in an alluvial-bedrock aquifer system(Colorado State University. Libraries, 2019) Cognac, Kristen, author; Ronayne, Michael, advisor; Sanford, William, committee member; Sale, Tom, committee memberThe response to pumping in multi-aquifer systems involves complex processes which can significantly affect regional water budgets. Particularly where long-term pumping has occurred, drawdown might take decades to propagate regionally. Failure to incorporate changes caused by long-term pumping into regional hydrogeologic conceptual models can lead to mischaracterization of critical water budget components like recharge, inter-aquifer fluxes, and groundwater-surface water exchange. Accurate description of these budget components is necessary for managing water resources and making predictions about future water supplies. This study analyzes long-term changes in an area of the Denver Basin aquifer system with high historical groundwater withdrawals to characterize the effects of long term pumping on recharge, inter-aquifer fluxes, and groundwater-surface water exchange. An evaluation of historical water level data (1960s to 2010s) documents large hydraulic head declines (>50m in some areas) and a deepening bedrock water table relative to the stream and alluvial aquifer. Results indicate a muti-decade transition from upward to downward hydraulic gradients in the vicinity of major streams, a change that affects the water budget of bedrock aquifers. Implications for regional water budgets are evaluated using a 2D variably saturated finite-difference model which quantifies fluxes across stream, alluvium, and bedrock interfaces in a vertical sequence. Modeling results demonstrate that long-term head decline can produce complex saturation conditions beneath the alluvial aquifer including a transition period of partial desaturation and ultimately a perched saturated zone in the alluvium underlain by an unsaturated region in the bedrock aquifer. The results illustrate how inter-aquifer fluxes eventually stabilize, with no further changes caused by additional lowering of the bedrock water table. Saturation levels and fluxes across interfaces are strongly dependent on geologic heterogeneity, particularly with respect to hydraulic conductivity contrasts between and within aquifers and the location and connectivity of channelized sandstones. Modeling results demonstrate the importance of considering heterogeneity and saturation when managing aquifers that have undergone long term pumping. The results of this study provide insight into the mechanics of long-term water budget change, including controls on the transition to induced recharge and recharge rates. This has important implications for assessing the aquifer response to ongoing and future stresses.Item Open Access Evaluating spatial and temporal controls on recharge fluxes in a stream-alluvial-bedrock aquifer system(Colorado State University. Libraries, 2023) Cognac, Kristen, author; Ronayne, Michael, advisor; Bailey, Ryan, committee member; Rathburn, Sara, committee member; Stright, Lisa, committee memberThe dynamics and timescales associated with natural and induced recharge to aquifers dictate whether and for how long groundwater resources are sustainable. This dissertation contains three studies which apply groundwater flow and geostatistical modeling to evaluate spatial and temporal controls on recharge fluxes in a stream-alluvial-bedrock system. Each study is based on a recharge mechanism that occurs within the Denver Basin aquifer system, a regionally significant water supply for which long-term pumping and active aquifer depletion call for improved characterizations of recharge. While recharge is the theme of this dissertation, I don't attempt to directly estimate recharge for the Denver Basin, but rather to investigate and expose dynamics of recharge that are essential for accurate conceptualizations and estimates of recharge. The first study investigates controls and timescales associated with streambed fluxes which are an important component of seepage recharge along mountain-front streams. Streambed fluxes are highly variable through time and space, having a range of implications for stream-aquifer processes. While spatial variations in streambed flux have been heavily characterized, temporal variability has been limited to short-term or low-frequency measurements. This study calculates high-frequency time series of Darcy-based streambed fluxes over a three-year period using water level and temperature inputs from shallow (<1.5m) nested streambed piezometers installed in two mountain-front streams in Colorado, USA. Results reveal important conclusions about controls and patterns of temporal variability. Three predominant temporal scales of variability, sub-daily (<1day), daily (>1d; <1y), and interannual (>1y), are quantified through statistical measures. Sub-daily variability was related to ET, temperature-induced changes in hydraulic conductivity, and variable stream stage while daily variability was highly seasonal and related to specific events on the channel (e.g., beaver dams). The magnitude of sub-daily variability was significant compared to daily variability (ratio 0.03 to 0.7). Annual median fluxes at each site varied across years, but typically remained consistent in order of magnitude and direction. A strong linear correlation characterizes the relationship between the daily variability and the median annual flux at individual sites, highlighting how sites with greater fluxes also exhibit greater temporal variability. The temporal flux variations documented in this study have important implications for calculations and interpretations of hyporheic exchange and groundwater recharge. Results provide a basis for quantifying temporal variations in streambed fluxes and highlight the extent to which fluxes vary over multiple timescales. Chapters 3 and 4 are organized to progress vertically downward within the system to investigate controls for inter-aquifer exchange between the alluvial and bedrock aquifer, an important component of recharge to the underlying bedrock aquifer system. In Chapter 3, the potential for and controls of hydraulic disconnection between the alluvial and bedrock aquifer are investigated. Hydraulic disconnection occurs when unsaturated conditions develop between a stream and water table causing seepage rates to stabilize with additional water table drawdown. In this study, I demonstrate that hydraulic disconnection can occur between an alluvial and bedrock aquifer when unsaturated conditions develop between the two water tables and inter-aquifer flow rates stabilize with subsequent drawdown. Variably saturated flow modeling is performed to simulate the effects of drawdown on alluvium to bedrock flow rates (A-B flow). Bedrock aquifer heterogeneity is represented through object-based geostatistical models that are conditioned to wellbore data from the Denver Basin aquifer system. The Monte Carlo framework includes 200 heterogeneity realizations across a range of sandstone fractions. Results document the formation of unsaturated regions beneath the alluvium in all models, particularly where sandstone channels underlie thinner low-permeability mudstones. Three-dimensional heterogeneity creates complex saturation patterns that result in localized flow paths, spatially varying disconnection, and a gradual transition to hydraulic disconnection as the regional water table is lowered. Successive changes in A-B flow decrease over the course of simulations by 80% to 99% and final rates approach stability as indicated by changes of <1% between successive stress periods. Of the 200 models, 190 reach full hydraulic disconnection and 10 conclude with a transitional flow regime. Dynamic connectivity metrics developed within the study strongly explain flow results. I also evaluate the aspects of heterogeneity that are most likely to produce disconnection, highlighting several factors that influence disconnection potential. Chapter 4 evaluates the potential for a beaver dam to drive flow across the alluvial-bedrock contact. Beavers construct dams which promote a range of surface and near-surface hydrologic processes, however, the potential for beavers to influence deeper aquifer dynamics is less often, if ever, considered. In this study I consider the potential for a beaver dam, specifically increased stream stage and width upstream of a dam, to drive deeper flow from an alluvial to bedrock aquifer. I utilize a numerical groundwater flow model to simulate the effects of the beaver dam on inter-aquifer exchange rates. The base case model is parameterized based on observations from a beaver dam constructed on Cherry Creek in 2020 and the stream-alluvial-bedrock aquifer sequence in the Denver Basin in previous chapters. I also test whether the influence of the beaver dam is sensitive to the alluvial-bedrock contact depth, beaver pond depth, and hydraulic properties by simulating flow across a range of sensitivity scenarios. Model results document an increase in alluvial to bedrock flow on the order of 0.5% to 4%, depending on the contact depth, beaver pond depth, and hydraulic properties. Changes in hydraulic head due to the dam propagate deep into the aquifer (>30m), highlighting the potential for deeper aquifer impacts. The effect of the beaver dam is greatest for shallow alluvial-bedrock contact depths, deeper pond depths, and lower hydraulic conductivity contrasts between the alluvial and bedrock aquifer. Overall, results document the potential for beavers to influence deeper aquifer fluxes where regional hydraulic gradients are downward, highlighting broader potential for beaver dams to enhance aquifer recharge in deeper aquifer settings.Item Open Access Hydrogeologic characterization of an alpine glacial till, Snowy Range, Wyoming(Colorado State University. Libraries, 2011) Houghton, Tyler B., author; Ronayne, Michael, advisor; Stednick, John, committee member; Sanford, William, committee memberCharacterization of sediment hydraulic properties is essential to understanding groundwater movement. In many mountain watersheds, surficial geologic material, such as glacial till, plays an important role in water and nutrient chemical cycling. Hydraulic properties of alpine glacial tills are infrequently measured, requiring efforts to characterize this complex geologic material. This research involved the use of multiple measurement techniques to determine the saturated hydraulic conductivity of surficial glacial tills at the Glacier Lakes Ecosystem Experiments Site (GLEES) in south-central Wyoming. During the summer of 2010, three in situ methods (double-ring infiltrometer, mini disk infiltrometer, and Guelph permeameter) were used to measure field-saturated hydraulic conductivity (K sat) at 32 locations around GLEES. Estimated K sat values obtained with the double-ring infiltrometer had a geometric mean of 0.12 cm/min and range of 0.007 to 0.40 cm/min. The Guelph permeameter had a geometric mean of 0.094 cm/min and range of 0.003 cm/min to 0.776 cm/min, and the mini disk infiltrometer obtained estimates with a geometric mean of 0.014 cm/min and ranged from 0.002 cm/min to 0.043 cm/min. The double-ring infiltrometer and Guelph permeameter measure K sat at a physical scale that is large enough to incorporate the large mixture of particle sizes that comprise the till. With a smaller physical measurement scale, the mini disk is predominantly influenced by the fine-grained fraction of the till. Using geometric mean K sat values obtained with the double-ring and mini disk infiltrometers and available snowpack data from the 2005 water year, a physically-based hydrologic and energy-balance model was used to simulate snowpack depletion, soil moisture changes, and groundwater recharge. Simulated sediment moisture changes were used to estimate vertical flow rates toward the water table. Using a higher K sat obtained at a larger physical measurement scale, the calculated flow rate 2 m below the surface is approximately three times that of the low K sat scenarios. Thus, the scale dependency of hydraulic conductivity is important when quantifying groundwater recharge in mountain watersheds.Item Open Access Hydrogeophysical investigation of unconfined aquifer drainage behavior using temporal microgravity and water level data(Colorado State University. Libraries, 2020) Sturdivant, Matthew, author; Ronayne, Michael, advisor; Sanford, William, committee member; Sale, Thomas, committee memberUnconfined aquifers are commonly characterized by an analysis of water level changes in response to groundwater pumping during an aquifer test. Traditional analytical models predict the rate and extent of water level changes based on transmissive and storage properties of the aquifer. These models commonly assume instantaneous and complete dewatering of the pore space above a falling water table, which neglects time-dependent storage changes in the unsaturated zone. By sensing pumping-induced water mass changes in both the saturated and unsaturated zones, gravity surveys provide an opportunity for improved characterization of unconfined aquifers. In this study, a time-lapse microgravimetric survey was performed during pumping from a shallow unconfined aquifer in northern Colorado. Water level data were collected at four monitoring wells located along a radial transect at 6.34, 15.4, 30.7. and 61.2 meters from the pumping well. Gravity measurements were collected adjacent to the second well at 15.4 meters. Pumping from the aquifer resulted in a water level decline ranging from 0.35 meters at the distant well to 1.5 meters at the closest well. A total of 3.89 ∙ 106 kg of water mass was pumped during the test, resulting in a decline in gravitational acceleration of 27.2 microGals at the fixed measurement location. The gravity data are not adequately explained by traditional analytical models that predict negligible mass changes as the water table beings to stabilize. This highlights potential inaccuracies in drawdown model assumptions that are not readily discernible with water level data alone.Item Open Access Hydrologic impacts of lined gravel pits, Colorado Front Range(Colorado State University. Libraries, 2018) Rach, Gavin, author; Ronayne, Michael, advisor; Sanford, William, committee member; Bailey, Ryan, committee memberSand and gravel quarries are a major source of natural aggregate. Gravel pits often excavate below the water table and therefore can influence alluvial aquifer groundwater flow directions and groundwater-surface water interaction. By regulation in the state of Colorado, low-permeability liners are installed after extraction to minimize water seepage into the pit. The liner impedes flow and disturbs the local water table, creating mounding on the upgradient side and shadow drawdown on the downgradient side. To better understand the magnitude and extent of these effects, numerical groundwater modeling was conducted for a study area along the Saint Vrain Creek alluvial aquifer in Colorado that contains an active gravel pit. The numerical model was based on a revised conceptual model, including a reinterpretation of the bedrock surface, and was calibrated using measured groundwater levels and estimated groundwater-surface water exchange rates constrained by streamflow gaging data. Two transient modeling scenarios were developed: a base case pre-mining scenario and a post-mining lined-pit scenario. The hydrologic effects of the pit liner were quantified through a detailed comparison of the scenarios. Model results indicate that the liner has a significant effect on water-table elevation in the vicinity of the pit during the non-irrigation season (October-March). In March, upgradient mounding produced by the liner exceeds 0.5 m at an approximate distance of 100 m, whereas the drawdown exceeds 0.3 m at this distance on the downgradient side of the pit. The magnitude of these liner-induced changes is less than other seasonal variability in hydraulic head, particularly the variability associated with irrigated agriculture (seasonally active irrigation ditches). During the irrigation season, simulated hydraulic heads are similar in both model scenarios, demonstrating that irrigation ditches are a major control on groundwater flow. Despite significant water table elevation change in parts of the year, groundwater discharge to the stream increased by 0.11% of the total streamflow at its maximum, demonstrating this particular pit liner has a negligible effect on the Saint Vrain Creek.Item Open Access Influence of subsurface heterogeneity on the performance of aquifer storage and recovery in the Denver Basin(Colorado State University. Libraries, 2016) Cannan, Catharine, author; Ronayne, Michael, advisor; Sale, Thomas, committee member; Sanford, William, committee memberAquifer storage and recovery (ASR) is a process through which water is injected into an aquifer for storage and recovered for later use. As water demand worldwide increases there is a growing need to evaluate alternative approaches to water storage, including ASR. Increasing our understanding of the fate of injected water and the subsurface conditions in which ASR is being performed can guide operational choices and decisions on the feasibility of ASR in new regions. Previous evaluations of ASR performance have often assumed homogeneity in the subsurface, overlooking the existence of preferential flow paths created by the combination of transmissive and non-transmissive inter-beds. Because these pathways can influence the lateral transport of water away from injection wells, ASR performance may be impacted. In this study a groundwater flow model within the Denver Basin, Colorado were used to evaluate ASR performance in a heterogeneous subsurface environment. Geologic data in the vicinity of Highlands Ranch, Colorado were synthesized to create heterogeneous, three-dimensional aquifer analogs using multiple-point geostatistical simulation. Flow simulation for these aquifer models was performed to evaluate ASR cycles comprised of injection, storage, and extraction phases, and results were compared to a homogeneous aquifer model. Three metrics were used to assess ASR performance: the extent of hydraulic head changes in the aquifer, fate of injected water particles, and recovery efficiency. Results show that the travel distance of injected water particles was influenced by the presence of heterogeneity and that preferential pathways increase both the variability and maximum distance traveled by injected water particles. Predicted recovery efficiency decreased slightly when heterogeneity was incorporated, while head change extent was far less sensitive to the presence of heterogeneous structures. These results demonstrate not only the influence of aquifer heterogeneity on ASR performance, but also the potential for geostatistical analysis and numerical modeling to be used as tools for planning future ASR operations.