Alan Fryar
University of Kentucky, Earth and Environmental science, Faculty Member
Because of well-integrated surface and subsurface drainage in karst terrains, springs can exhibit relatively rapid hydraulic, chemical, and thermal responses to storms. In urbanized karst basins, impervious cover, stream channelization,... more
Because of well-integrated surface and subsurface drainage in karst terrains, springs can exhibit relatively rapid hydraulic, chemical, and thermal responses to storms. In urbanized karst basins, impervious cover, stream channelization, and utility infrastructure can alter infiltration, provide alternate pathways for subsurface flow, and affect ambient water quality. We combined continuous logging of electrical conductivity (EC) and water temperature with analyses of stable isotopes (deuterium and oxygen-18) to differentiate focused and diffuse recharge in a karst basin in Lexington, Kentucky, during 2018. Logging occurred at the McConnell Springs Blue Hole and a sinkhole that drains to it; isotopes, specific conductance, and temperature were manually monitored at those sites and along two losing stream reaches. Water temperature at McConnell Springs and stable isotope abundances showed seasonal variability. The Blue Hole responded within hours to stormwater infiltration at the sink...
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Karst springs are important water sources for both human needs and environmental flows. The responses of karst springs to hydrometeorological factors vary depending on local conditions. In this study, we investigated Martandnag spring in... more
Karst springs are important water sources for both human needs and environmental flows. The responses of karst springs to hydrometeorological factors vary depending on local conditions. In this study, we investigated Martandnag spring in the Liddar catchment in the Kashmir valley of northern India. We used statistical time series (autocorrelation and cross-correlation) and machine-learning (ML) techniques (random forest regression (RFR) and support vector regression (SVR)) to characterize how rainfall, temperature, and snow cover affect the karst spring flow and predict the future responses of the spring stage based on climate scenarios, in the Intergovernmental Panel on Climate Change Assessment Report 6. The statistical time series showed that the memory effect of Martandnag spring varies from 43 to 61 days, indicating moderate karstification and a relatively high storage capacity of the karst aquifer in the Liddar catchment. The delay between recharge and discharge varies from 13...
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The Ganges River delta complex contains a transboundary aquifer system shared between India and Bangladesh. Although it serves as the main freshwater source for the population inhabiting the delta, the aquifer system is severely... more
The Ganges River delta complex contains a transboundary aquifer system shared between India and Bangladesh. Although it serves as the main freshwater source for the population inhabiting the delta, the aquifer system is severely contaminated with arsenic (As). This study aimed to determine the control of the delta hydrostratigraphy on the regional-scale depth distribution of As within the aquifer system. We developed the first high-resolution, regional-scale, transboundary hydrostratigraphic model of the Ganges River delta and analyzed the patterns of As distribution as a function of the hydrostratigraphy. Model results indicate that, despite the presence of a single aquifer system across the delta, the hydrostratigraphy is spatially variable and can be architecturally divided into three distinct aquifer subsystems from northwest to southeast: a single, thick continuous aquifer (type I); a vertically segregated, semi-confined aquifer subsystem (type II); and a multilayered, nearly c...
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POSTER: The Jackson Purchase region of western Kentucky consists of Coastal Plain sediments near the northern margin of the Mississippi Embayment. Within this region is the Paducah Gaseous Diffusion Plant (PGDP), a uranium enrichment... more
POSTER: The Jackson Purchase region of western Kentucky consists of Coastal Plain sediments near the northern margin of the Mississippi Embayment. Within this region is the Paducah Gaseous Diffusion Plant (PGDP), a uranium enrichment facility operated by the US Department of Energy. At PGDP, a Superfund site, soil and groundwater studies have provided subsurface lithologic data from hundreds of monitoring wells and borings. Despite preliminary efforts by various contractors, these data have not been utilized to develop detailed stratigraphic correlations of sedimentary units across the study area. In addition, sedimentary exposures along streams in the vicinityof PGDP have not been systematically described beyond the relatively simple geologic quadrangle maps published by the US Geological Survey in 1966-67. This study integrates lithologic logs, other previous site investigation data, and outcrop mapping to provide a compilation of near-surface lithologic and stratigraphic data for...
Research Interests: Geology and Geologic map
Springs are ecosystems influenced by the exposure of groundwater at the Earth’s surface. Springs are abundant and have played important, highly interactive ecological, cultural, and socio-economic roles in arid, mesic, and subaqueous... more
Springs are ecosystems influenced by the exposure of groundwater at the Earth’s surface. Springs are abundant and have played important, highly interactive ecological, cultural, and socio-economic roles in arid, mesic, and subaqueous environments throughout human evolution and history. However, springs also are widely regarded as being highly threatened by human impacts. Cantonati et al. (2020a) recommended increased global awareness of springs, including basic mapping, inventory and assessment of the distribution and ecological integrity of springs. We conducted a preliminary global analysis on the ecological integrity of springs by reviewing information on the distribution, ecohydrogeology, associated species, kinds and intensity of human uses, and level of ecological impairment of spring ecosystems. We reviewed information on an estimated 250,000 spring ecosystems among 78 countries across much of the world. Available literature on spring ecological integrity is sparse, widely scattered, and spatially erratic, with major gaps in knowledge. We report large differences in the quality and extent of information among countries and continents, with only moderate data availability even among developed countries, and limited information across most of the developing world. Among countries with available data, ecological impairment of springs is everywhere rampant, sometimes exceeding 90% in developed regions. Impairment among Holarctic nations is generally negatively related to distance from human development, elevation, and latitude, but such patterns are less evident in Africa, Australia, and South America. Declining trends in ecosystem condition, compounding threat factors, and spring-dependent population declines, extirpation, and extinctions of plants, invertebrates, fish, and herpetofauna are widely reported. Overall, available information indicates a global crisis in spring ecosystem integrity, with levels of ecosystem impairment ranging from Vulnerable to fully Collapsed. The threats to aquifers and the ecological integrity of springs vary spatially. Many springs are impaired by local impacts due to flow diversion, geomorphic alteration, land use practices, recreation impacts, and the introduction of non-native species. These threats can be reduced through education, rehabilitation of geomorphology and habitat quality, and species reintroductions if the supporting aquifer remains relatively intact. However, springs also are widely threatened by regional to global factors, including groundwater extraction and pollution, as well as climate change. Such coarse-scale, pre-emergence impacts negatively affect the sustainability of spring ecosystems and the aquifers that support them. Improving understanding and stewardship of springs will require much additional systematic inventory and assessment, improved information management, and reconsideration of basic conservation concepts (e.g., habitat connectivity), as well as cultural and socio-economic valuation. Substantial societal recognition, discussion, and policy reform are needed within and among nations to better protect and sustainably rehabilitate springs, their supporting aquifers, and the spring-dependent human and biotic populations that depend upon them
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Groundwater flow in karst terrains is difficult to map because it can be concentrated through conduits that do not necessarily coincide with the surface features. We applied electrical resistivity (ER) and self-potential (SP) techniques... more
Groundwater flow in karst terrains is difficult to map because it can be concentrated through conduits that do not necessarily coincide with the surface features. We applied electrical resistivity (ER) and self-potential (SP) techniques at three sites to locate an inferred trunk conduit feeding a major spring in the Inner Bluegrass region of Kentucky (USA). Royal Spring is the primary water supply for the city of Georgetown; the upper part of its basin coincides with the Cane Run watershed. ER profiles (972 m total length) were measured using a dipole–dipole electrode configuration with 2- to 3-m spacing. SP measurements were taken along those ER lines and an additional test profile (230 m) using one stationary reference electrode and another roving electrode at a fixed interval. The SP technique has been used by many researchers to detect the electro kinetic potential generated by groundwater flow. The low resistivity of water in the conduit, as compared to the high background resi...
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The first documented interpretation of the regional-scale hydrostratigraphy and groundwater flow is presented for a ∼21,000-km2 area of the arsenic-affected districts of West Bengal [Murshidabad, Nadia, North 24 Parganas and South 24... more
The first documented interpretation of the regional-scale hydrostratigraphy and groundwater flow is presented for a ∼21,000-km2 area of the arsenic-affected districts of West Bengal [Murshidabad, Nadia, North 24 Parganas and South 24 Parganas (including Calcutta)], India. A hydrostratigraphic model demonstrates the presence of a continuous, semi-confined sand aquifer underlain by a thick clay aquitard. The aquifer thickens toward the east
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Tuart (Eucalyptus gomphocephala) is a woodland tree native to the Swan Coastal Plain of Western Australia supporting habitat for vulnerable fauna (e.g. western ringtail opossum) and threatened flora (e.g. Acacia benthamii). Stands have... more
Tuart (Eucalyptus gomphocephala) is a woodland tree native to the Swan Coastal Plain of Western Australia supporting habitat for vulnerable fauna (e.g. western ringtail opossum) and threatened flora (e.g. Acacia benthamii). Stands have experienced a reduction in size from ~ 112,000 hectares in 1996 to ~ 30,000 hectares at present. The decline has raised concerns ranging from biodiversity and ecosystem functioning to cultural and economic values. The cause of the decline remains unknown, but factors currently under investigation include hydrology and water quality, fire and competition, pests and pathogens, environmental correlates, and nutrition. Research was conducted to investigate possible hydrologic causes of Tuart decline within Yalgorup National Park on the basis of three observed processes: a 15-20% reduction in winter rainfall since the 1970s, salinity rise in Lake Clifton (a lake within the park) beginning in the 1990s, and the 1993 construction of a channel linking the estuary to the Indian Ocean. ArcGIS was used to construct maps of the study area, which was composed of 24 Tuart sites characterized as healthy, intermediate, or unhealthy. State Department of Water (DoW) well bores and Australian Bureau of Meteorology (BoM) weather stations located near the study area were identified. Bore and precipitation data were then obtained from each organization’s online database. These data were used to identify trends in precipitation and bore-water levels to investigate the effects of the shift to a lower rainfall regime, channel construction, and salinity increase in Lake Clifton. This led to a proposed mechanism of salinity increase in Lake Clifton and the surrounding groundwater, which may or may not be linked to the observed decline in the Tuart population.
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ABSTRACT Because of preferential flowpaths via features such as sinkholes and conduits, karst aquifers are susceptible to non-point-source pollution from agricultural and urban drainage. With many karst aquifers being drinking- water... more
ABSTRACT Because of preferential flowpaths via features such as sinkholes and conduits, karst aquifers are susceptible to non-point-source pollution from agricultural and urban drainage. With many karst aquifers being drinking- water sources, pathogens are contaminants of public health concern. Monitoring of microbial parameters (total coliforms [TC], atypical colonies [AC] and fecal coliform bacteria [FC]) transpired biweekly from December 2002 March 2004 and weekly from February October 2005 at Blue Hole Spring, which drains outlying farm lands and the town of Versailles in the Inner Bluegrass Region of Kentucky. Physicochemical parameters (discharge, temperature, specific conductance, and pH) were measured continuously during the entire period. The AC/TC ratio, which had been employed only in surface water-quality studies, was used with FC counts, precipitation and discharge data to determine sources of fecal loading to ground water as result of land-use practices. An AC/TC ratio 10 during dry periods and < 10 during wet periods, while the 2005 data demonstrated a very irregular pattern. The difference in these two data sets indicated a compositional change within the groundwater basin between the two sampling periods, perhaps as a result of construction at a sewage treatment plant adjoining the spring. Solute (rhodamine WT fluorescent dye and bromide) and particle (1-mum diameter fluorescent latex microspheres) tracer tests were conducted during summer 2006 to examine contaminant mobility within the system under base-flow and storm-flow conditions. Rainfall was limited prior to the base-flow trace, totaling 0.025 cm within 2 weeks prior to the slug injection. Base-flow discharge averaged 400 m3/s and solute breakthrough began ~ 7.5 hours post injection and cleared the system after 77 hours. For the storm-flow trace, rainfall totaled 3.12 cm prior to injection, with another 9.35 cm of rainfall occurring over the two week monitoring period. Spring discharge during the storm-flow trace averaged 0.443 m3/s, with a maximum of 0.503 m3/s. Under storm-flow conditions solute breakthrough began ~ 2.33 hours post injection, with particle breakthrough beginning ~ 2.5 hours post injection. Bromide concentrations at the spring were < 0.1 ppm (the detection limit, or DL) 5.5 hours after injection, while rhodamine WT concentrations were < DL (0.1 ppb) 14 hours post injection. Microspheres were detected at the spring until 164 hours after injection. These traces demonstrate that storms in this karst basin can accelerate solute movement, and particles can remain mobile for as long as 1 week after introduction.
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To monitor groundwater salinization due to seawater intrusion (SWI) in the aquifer of the eastern Nile Delta, Egypt, we developed a predictive regression model based on an innovative approach using SWI indicators and artificial... more
To monitor groundwater salinization due to seawater intrusion (SWI) in the aquifer of the eastern Nile Delta, Egypt, we developed a predictive regression model based on an innovative approach using SWI indicators and artificial intelligence (AI) methodologies. Hydrogeological and hydrogeochemical data of the groundwater wells in three periods (1996, 2007, and 2018) were used as input data for the AI methods. All the studied indicators were enrolled in feature extraction process where the most significant inputs were determined, including the studied year, the distance from the shoreline, the aquifer type, and the hydraulic head. These inputs were used to build four basic AI models to get the optimal prediction results of the used indicators (the base exchange index (BEX), the groundwater quality index for seawater intrusion (GQISWI), and water quality). The machine learning models utilized in this study are logistic regression, Gaussian process regression, feedforward backpropagation neural networks (FFBPN), and deep learning-based long-short-term memory. The FFBPN model achieved higher evaluation results than other models in terms of root mean square error (RMSE) and R2 values in the testing phase, with R2 values of 0.9667, 0.9316, and 0.9259 for BEX, GQISWI, and water quality, respectively. Accordingly, the FFBPN was used to build a predictive model for electrical conductivity for the years 2020 and 2030. Reasonable results were attained despite the imbalanced nature of the dataset for different times and sample sizes. The results show that the 1000 μS/cm boundary is expected to move inland ~9.5 km (eastern part) to ~10 km (western part) to ~12.4 km (central part) between 2018 and 2030. This encroachment would be hazardous to water resources and agriculture unless action plans are taken.
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Karst aquifers are susceptible to contamination by pathogenic microorganisms, such as those found in human and animal waste, because the surface and subsurface drainage are well integrated through dissolution features. Fecal contamination... more
Karst aquifers are susceptible to contamination by pathogenic microorganisms, such as those found in human and animal waste, because the surface and subsurface drainage are well integrated through dissolution features. Fecal contamination of water is commonly assessed by the concentration of thermotolerant coliform bacteria, especially E. coli. This method is time-consuming, taking ≥18 h between the start of incubation and subsequent enumeration, as well as the time required to collect and transport samples. We examined the utility of continuous monitoring of tryptophan-like fluorescence (TLF) as a real-time proxy for E. coli in a mixed-land-use karst basin in the Inner Bluegrass region of central Kentucky (USA). Two logging fluorometers were sequentially deployed at the outlet spring. During storm flow, TLF typically peaked after discharge, which suggests that TLF transport in the phreatic conduit is likely related to sediment transport. The ability of TLF and other parameters (48 ...
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Groundwater potential maps constitute a valuable tool for groundwater sustainable management in arid regions. In this study, a groundwater potential map was developed for the Asadabad plain (Iran). The method deployed remote sensing... more
Groundwater potential maps constitute a valuable tool for groundwater sustainable management in arid regions. In this study, a groundwater potential map was developed for the Asadabad plain (Iran). The method deployed remote sensing techniques and hierarchical analysis, while geoelectric data were used to verify the results of the study. The methodology used extracted information from thematic maps including lithology, the density of lineaments, drainage density, topography, slope, slope aspect, land use, distance from streams, distance from lineaments, rainfall, and air temperature. All different layers of information were classified as standard maps by expert judgment and field visits, and each category is ranked from 1 to 10 according to its degree of importance. Also, each layer is assigned an appropriate weight based on the groundwater potential using the hierarchical analysis process. The resulting map of the study area was quantitatively and qualitatively zoned into five classes: excellent, good, moderate, very low, and poor. The results obtained were compared with field electrical resistivity surveys and a high correlation was found. The results obtained from the groundwater potential map were validated by comparison with lithologic and water-level data, thus demonstrating the accuracy of the applied method.
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The water supply for Kyiv (Ukraine) is a seasonally and spatially variable mixture of both ground and surface water. This water supply is vulnerable to the effects of climate change, pollution, and geopolitical conflict. Climate change... more
The water supply for Kyiv (Ukraine) is a seasonally and spatially variable mixture of both ground and surface water. This water supply is vulnerable to the effects of climate change, pollution, and geopolitical conflict. Climate change has resulted in changing precipitation patterns, potentially altering the balance between ground and surface water utilization. Additionally, the ongoing conflict makes a holistic understanding of water resources and pathways critical for water management. This study uses water stable isotopes as tracers for water sources and the importance of different reservoirs in water management.For this study tap water, surface water, groundwater, and precipitation were collected over 14 months (2019-2020) in Kyiv and nearby Boryspil, Brovary, and Boyarka and measured for hydrogen (𝛿2H) and oxygen (𝛿18O) stable isotope ratios. Precipitation data was used to capture seasonal variability in storm trajectories and create a meteoric water line. These results were th...
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Spring discharge hydrographs can provide information on karst aquifer connectivity and responses to precipitation. However, few studies have conducted time-series analyses of spring hydrographs over multi-decadal time scales. We examine... more
Spring discharge hydrographs can provide information on karst aquifer connectivity and responses to precipitation. However, few studies have conducted time-series analyses of spring hydrographs over multi-decadal time scales. We examine daily discharge for three large karst springs and daily precipitation for adjoining weather stations during 1928–2019 in the Salem Plateau of southern Missouri, one of the major karst regions in the USA. For different time periods, we conducted baseflow index calculations and time-series (autocorrelation, spectral density, and cross-correlation with precipitation) analyses for discharge data, and Mann–Kendall (MK) trend analyses for discharge and precipitation data. Hydrograph separation indicates discharge is baseflow-dominated (86–94%) at all three springs. The memory effect is lower for Bennett Spring (with an auto-correlation lag time 29–41 days) than for Big Spring (60–92 days) and Greer Spring (77–112 days). Spectral density analysis indicates ...
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The spatial and temporal changes of water resources of Iraq were evaluated using the Gravity Recovery and Climate Experiment (GRACE) data for the period 2002–2019. The rate of change and significance of the change in terrestrial water... more
The spatial and temporal changes of water resources of Iraq were evaluated using the Gravity Recovery and Climate Experiment (GRACE) data for the period 2002–2019. The rate of change and significance of the change in terrestrial water storage (TWS) derived from different GRACE solutions were estimated using Sen’s slope estimator and Mann–Kendall test. The sustainability of water resources was evaluated using reliability–resiliency–vulnerability indicators. Results indicated a significant decrease in water availability. The reliability (range 0.22–0.30) and resiliency (range 0.01–0.23) of water resources were low. The estimated vulnerability (range of 0–1) was highest in the north and lowest in the south and southwest. The calculated sustainability of water resources was generally low (range 0–0.36) and was higher in southern and western regions relative to northern and central areas. Anthropogenic activities and climate change (increasing temperature) play major roles in changes in water availability in Iraq.
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... Sediment accumulates in the basin from the Ganges, Brahmaputra, and Meghna (GBM) river systems and is dispersed into the Bay of Bengal, forming the largest ... The basin has profuse groundwater resources, but the architecture of the... more
... Sediment accumulates in the basin from the Ganges, Brahmaputra, and Meghna (GBM) river systems and is dispersed into the Bay of Bengal, forming the largest ... The basin has profuse groundwater resources, but the architecture of the aquifers is not yet well resolved. ...
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Research Interests: Thermodynamics, Arsenic, Groundwater, Environmental Monitoring, Multidisciplinary, and 12 moreIndia, Indian Ocean, Environmental Sciences, Contaminant hydrology, Theoretical Models, Fresh water, Dissolved Organic Carbon, Redox, Geologic Sediments, Oxidation-Reduction, Geological Processes, and contaminant
Research Interests: Geology and Coastal Plain
Knowledge of the groundwater potential, especially in an arid region, can play a major role in planning the sustainable management of groundwater resources. In this study, nine machine learning (ML) algorithms—namely, Artificial Neural... more
Knowledge of the groundwater potential, especially in an arid region, can play a major role in planning the sustainable management of groundwater resources. In this study, nine machine learning (ML) algorithms—namely, Artificial Neural Network (ANN), Decision Jungle (DJ), Averaged Perceptron (AP), Bayes Point Machine (BPM), Decision Forest (DF), Locally-Deep Support Vector Machine (LD-SVM), Boosted Decision Tree (BDT), Logistic Regression (LG), and Support Vector Machine (SVM)—were run on the Microsoft Azure cloud computing platform to model the groundwater potential. We investigated the relationship between 512 operating boreholes with a specified specific capacity and 14 groundwater-influencing occurrence factors. The unconfined aquifer in the Nineveh plain, Mosul Governorate, northern Iraq, was used as a case study. The groundwater-influencing factors used included elevation, slope, curvature, topographic wetness index, stream power index, soil, land use/land cover (LULC), geolog...
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What is Karst? Karst refers to terrain largely drained by subsurface conduits and caves. Karst landscapes are characterized by surface features such as springs, sinkholes, shallow depressions, and rolling hills (Figure 1). Karst regions... more
What is Karst? Karst refers to terrain largely drained by subsurface conduits and caves. Karst landscapes are characterized by surface features such as springs, sinkholes, shallow depressions, and rolling hills (Figure 1). Karst regions are also known for their subsurface or below-ground features such as conduits and caves (Figure 2). What makes a karst region unique is the way runoff drains from the land. In karst regions, some of the runoff flows into surface features such as sinkholes where it then travels underground. Some of this infiltrated water re-emerges at springs (Figure 1a), and some continues moving underground. An aquifer is a body of water-bearing rock located underground. Two important features of aquifers are how water is stored in the rock and how water moves through the rock. Rocks and sediment contain empty space known as pore space which can be filled with water (Figure 3). Different types of rocks and soil have different amounts of pore space, hence are able to...
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Karst refers to terrain largely drained by subsurface conduits and caves. Karst landscapes are characterized by surface features such as springs, sinkholes, shallow depressions, and rolling hills. Karst regions are also known for their... more
Karst refers to terrain largely drained by subsurface conduits and caves. Karst landscapes are characterized by surface features such as springs, sinkholes, shallow depressions, and rolling hills. Karst regions are also known for their subsurface or below-ground features such as conduits and caves. What makes a karst region unique is the way runoff drains from the land. In karst regions, some of the runoff flows into surface features such as sinkholes where it then travels underground. Some of this infiltrated water re-emerges at springs, and some continues moving underground.