Environmental isotopes in groundwater hydrology, 1980, Fontes J.

Agricultural chemicals at the outlet of a shallow carbonate aquifer, 1996, Felton Gk,

A groundwater catchment, located in Woodford and Jessamine Counties in the Inner Bluegrass of Kentucky, was instrumented to develop long-term flow and water quality data. The land uses on this 1 620-ha catchment consist of approximately 59% in grasses consisting of beef farms, horse farms, and a golf course; 16% row crops; 6% orchard; 13% forest; and 6% residential. Water samples were analyzed twice a week for, Ca, Mg, Na, Cl-, HCO3-, SO4=, NO3-, total solids, suspended solids, fecal coliforms, fecal streptococci, and triazines. Flow rate and average ambient temperature were also recorded. No strong linear relationship was developed between chemical concentrations and other parameters. The transient nature of the system was emphasized by one event that drastically deviated from others. Pesticide data were summarized and the ''flushing'' phenomena accredited to karst systems was discussed. The total solids content in the spring was consistent at approximately 2.06 mg/L. Fecal bacteria contamination was well above drinking water limits (fecal coliform and fecal streptococci averages were 1 700 and 4 300 colony-forming-units/100 mL, respectively) and the temporal variation in bacterial contamination was not linked to any other variable

Aufeis of the Firth River basin, Northern Yukon Canada: Insights into permafrost hydrogeology and Karst, 1997, Clark Id, Lauriol B,

The 31-km(2) aufeis ice sheet of the upper Firth River holds a wealth of information on groundwater hydrology in periglacial environments. Baseflow recession calculations, corrected for aufeis storage (12% of basin discharge), indicate specific groundwater recharge rates of up to 100 mm yr(-1) (up to 50% of runoff), suggesting a significant proportion of drainage from karst. The upper Firth River aufeis is a composite aufeis, with discrete baseflow contributions from different watersheds. Since the late Pleistocene, annual growth of the aufeis has exerted a strong control on lateral erosion and the local river channel geomorphology. Two groundwater recharge processes are distinguished on the basis of carbonate geochemistry and 8(13)C: (1) Methanogenic groundwaters, with C-13(DIC) up to -3.3 parts per thousand, are recharged through saturated soils underlain by permafrost; conditions which support anaerobic consumption of dissolved organic carbon (DOC) and produce up to 700 mu g-CH4 L-1 (calculated), and (2) Karst groundwaters, with C-13-depleted DIC, recharged through unsaturated soils and circulate through fissured talik in the carbonate bedrock. Most drainage from the region shows varying contributions of these two groundwaters, although a greater contribution from the methanogenic groundwaters occurs in north-facing watersheds. The 8(13)C values far cryogenic calcite precipitates in the ice indicate that the karst groundwaters are the major contribution to aufeis growth. The combined use of 8(13)C(DIC) and geochemistry may be a useful tool to quantify methanogenesis in northern watersheds

Microorganisms as tracers in groundwater injection and recovery experiments: a review, 1997, Harvey R. W. ,

Modern day injection and recovery techniques designed to examine the transport behavior of microorganisms in groundwater have evolved from experiments conducted in the late 1800s, in which bacteria that form red or yellow pigments were used to trace flow paths through karst and fractured-rock aquifers. A number of subsequent groundwater hydrology studies employed bacteriophage that can be injected into aquifers at very high concentrations (e.g., 10(13) phage ml(-1)) and monitored through many log units of dilution to follow groundwater flow paths for great distances, particularly in karst terrain. Starting in the 1930s, microbial indicators of fecal contamination (particularly coliform bacteria and their coliphages) were employed as tracers to determine potential migration of pathogens in groundwater. Several injection and recovery experiments performed in the 1990s employed indigenous groundwater microorganisms (both cultured and uncultured) that are better able to survive under in situ conditions. Better methods for labeling native bacteria (e.g. by stable isotope labeling or inserting genetic markers, such as the ability to cause ice nucleation) are being developed that will not compromise the organisms' viability during the experimental time course

Structure, flow, and generalized conductivity scaling in fracture networks, 1999, Margolin G. , Berkowitz B. , Scher H.

We present a three-dimensional (3-D) model of fractures that within the same framework, allows a systematic study of the interplay and relative importance of the two key factors determining the character of flow in the system. The two factors of complexity are () the geometry of fracture plane structure and interconnections and (2) the aperture variability within these planes. Previous models have concentrated on each separately. We introduce anisotropic percolation to model a wide range of fracture structures and networks. The conclusion is that either of these elements, fracture geometry and aperture variability, can give rise to channeled flow and that the interplay between them is especially important for this type of flow. Significant outcomes of our study are (1) a functional relationship that quantifies the dependence of the effective hydraulic conductivity on aperture variability and on the network structure and fracture element density, (2) a relation between aperture variability and the Peclet number, and (3) a basis for a new explanation for the field-length dependence of permeability observed in fractured and heterogeneous porous formations.

Uncalculated impacts of unsustainable aquifer yield including evidence of subsurface interbasin flow, 2000, Bacchus St,

Unsustainable withdrawals from regional aquifers have resulted in adverse impacts considerable distances from the point locations of supply wells. In one area of the southeastern (SE) Coastal Plain, conservative estimates for repair/replacement of some residential wells damaged or destroyed by unsustainable yield from the Floridan aquifer system exceeded $4 million. However, a comprehensive assessment of damage/economic loss to private property and public resources due to unsustainable yield from that regional karat aquifer has not been made. Uncalculated direct costs to home-owners from damage attributed to those withdrawals are associated with destruction of homes from increased sinkhole formation, devalued waterfront property, and removal of diseased and dead trees. Examples of other uncalculated economic burdens resulting from unsustainable aquifer yield in the SE Coastal Plain include: (1) irreversible damage to the aquifer matrix and concomitant increased potential for groundwater contamination, (2) large-scale wildfires with subsequent degradation of air quality, debilitation of transportation corridors, and destruction of timber, wildlife habitat and property, and (3) destruction of 'protected' natural areas. This paper provides a general background of the regional Floridan aquifer system's karst characteristics, examples of known impacts resulting from ground water mining in the SE Coastal Plain, and examples of additional damage that may be related to unsustainable yield from the Upper Floridan aquifer. Costs of these impacts have not been calculated and are not reflected in the price users pay for ground water. Evidence suggests that the classic watershed management approach must be revised in areas with mined regional karst aquifers to include impacts of induced recharge from the surficial aquifer, and subsurface interbasin flow. Likewise, associated impacts to surface water and interrelated systems must be calculated The true cost of groundwater mining to this and future generations should be determined using a multidisciplinary approach

The hydrologic catchment area of a chain of karst wetlands in central Pennsylvania, USA, 2003, O'driscoll M. A. , Parizek R. R. ,

Shallow depressions found in karst terrains may contain wetlands (karst pans) that fluctuate seasonally in response to climatic conditions. This study examined the ground-water hydrology of a chain of 17 wetlands, ranging in size from 0.06 to 0.4 hectares, located in an Appalachian karst valley in central Pennsylvania, USA. The study objective was to determine the contributing area of wetland source waters. A variety of hydraulic head, soil stratigraphy, and water chemistry-data indicate that the combined contributing areas of these wetland ponds extend to a maximum distance of approximately 150 in from the ponds. The hydrologic catchment area of the ponds during January and February, 1999 (approximately 2-8 hectares) was significantly smaller than catchment area based on topography (69 hectares). The water source of the wetlands consists of direct precipitation inputs and shallow (0.5-6 m) perched ground water. The hydrologic catchment area of the ponds expands during wet periods and contracts during dry periods. The ponds have been shown to be perched above the regional water table

Groundwater Hydrology of a Coastal Conduit Carbonate Aquifer: Caribbean Coast of the Yucatán Peninsula, México, PhD Thesis, 2004, Beddows, Patricia A.

Over 500 km of horizontally extensive submerged cave passages have been explored within the density-stratified carbonate aquifer of the Caribbean coast of the Yucatan Peninsula. These drain the large inland recharge area to the coastal margin and represent important regional-scale anisotropic permeability features. However, conventional theory is inadequate to explain this aquifer where conduit flows dominate within a high permeability matrix. Cave diving and surface observations have been used to develop a regional and multi-seasonal dataset of the density-stratified water column, and the circulation within the fresh and saline waters. A sharp mixing zone (MZ; 0.3 - 4 m thick) separates a cool fresh water lens (FWL) from a warmer saline water zone (SWZ) within the conduits. The SWZ temperature is highest at the coast (~ 28.0 oC) and decreases to ~ 25.5 oC at 10 km inland, while the FWL temperature is spatially constant (25 ± 0.2 oC, n = 33). The MZ has subtle isostatic response (2 - 10 cm) to the semi-diurnal coastal tides, however it remains at an almost uniform depth (within 1 m) despite significant water table variations (> 1 m). Thus, the FWL volume changes in direct proportion to the water table elevation. Previous Yucatan water budgets indicate that 15 % of precipitation recharges the aquifer, however this study shows that > 30 % is required to provide the observed coastal discharge. At least two flow regimes occur within the SWZ. Shallow SWZ flow (to ~ 5 m below the MZ) circulates with alternating periods of net inflow and outflow depending on the mean sea level. This regional reversing flow is substantiated by the inflow of warm marine water at the coast and a pattern of decreasing temperature along the flowpath with distance inland. At greater depth below the MZ (~ 5 - 45 m), saline water flows continuously inland irrespective of sea level. It is proposed that deeper saline flows may represent a cross-platform saline circulation, driven principally by a large east-west ocean head difference (~ 20 - 40 cm).

REVIEW OF KRESIC, N. AND STEVANOVIC, Z. (EDITORS) 2010. GROUNDWATER HyDROLOGy OF SPRINGS: ENGINEERING, THEORy, MANAGEMENT, AND SUSTAINABILITy. AMSTERDAM, BUTTERWORTH-HEINEMANN (ELSEVIER); 573 PAGES. ISBN 978-1-85617-502-9., 2010, Ford D. C.

Spring Geochemistry, 2010, White, W.

Groundwater hydrology of springs - Engineering, theory, management, and sustainability, 2010,

Edited by two world-renowned hydrologists, this book will provide civil and environmental engineers with a comprehensive reference for managing and sustaining the water quality of springs. With contributions from experts from around the world, this text covers many of the world's largest springs, providing a unique global perspective on how engineers around the world are utilizing engineering principles for coping with problems such as: Mismanagement, overexploitation and their impacts on both water quantity and quality. The book is divided into two parts: Part One will explain the theory and principles of hydrology as they apply to springs while, Part Two will provide a rare look into the engineering practices used to manage some of the most important springs from around the world.

Groundwater Hydrology of Water Resource Series Water is an essential environmental resource and one that needs to be properly managed. As the world places more emphasis on sustainable water supplies, the demand for expertise in hydrology and water resources continues to increase. This series is intended for professional engineers, who seek a firm foundation in hydrology and an ability to apply this knowledge to solve problems in water resource management. Future books in the series are: Groudwater Hydrology of Springs (2009), Groudwater Hydrology of River Basins (2009), Groudwater Hydrology of Aquifers (2010), and Groudwater Hydrology of Wetlands (2010). First utilized as a primary source of drinking water in the ancient world, springs continue to supply many of the world's cities with water. In recent years their long-term sustainability is under pressure due to an increased demand from groundwater users. Edited by two world-renowned hydrologists, Groundwater Hydrology of Springs: Theory, Management, and Sustainability will provide civil and environmental engineers with a comprehensive reference for managing and sustaining the water quality of Springs. With contributions from experts from around the world, this book cover many of the world's largest springs, providing a unique global perspective on how engineers around the world are utilizing engineering principles for coping with problems such as: mismanagement, overexploitation and their impacts both water quantity and quality. The book will be divided into two parts: part one will explain the theory and principles of hydrology as they apply to Springs while part two will provide a rare look into the engineering practices used to manage some of the most important Springs from around the world.

Groundwater Hydrology of Springs: Theory, Management, and Sustainability, 2011, Aa

Computational Investigation of Fundamental Mechanisms Contributing to Fracture Dissolution and the Evolution of Hypogene Karst Systems, 2011, Chaudhuri A. , Rajaram H. , Viswanathan H. S. , Zyvoloski G. , Stauffer P. H.

Hypogene karst systems evolve by dissolution resulting from the cooling of water flowing upward against the geothermal gradient in limestone formations. We present a comprehensive coupled-process model of fluid flow, heat transfer, reactive transport and buoyancy effects to investigate the origin of hypogene karst systems by fracture dissolution. Our model incorporates the temperature and pressure dependence of the solubility and dissolution kinetics of calcite. Our formulation inherently incorporates mechanisms such as “mixing corrosion” that have been implicated in the formation of hypogene cave systems. It also allows for rigorous representation of temperature-dependent fluid density and its consequences at various stages of karstification. The model is applied to investigate karstification over geological time scales in a network of faults/fractures that serves as a vertical conduit for upward flow. We considered two different conceptual hydrogeologic models. In the first model, the upward flow is controlled by a constant pressure gradient. In the second model, the flow is induced by topographic effects in a mountainous hydrologic system. During the very early stages of fracture growth, there is a positive feedback between fluid flow rate, heat transfer and dissolution. In this stage the dissolution rate is largely controlled by the retrograde solubility of calcite and aperture growth occurs throughout the fracture. For the first model, there is a period of slow continuous increase in the mass flow rate through the fracture, which is followed by an abrupt rapid increase. We refer to the time when this rapid increase occurs as the maturation time. For the second model of a mountainous hydrologic system, the fluid flux through the fracture remains nearly constant even though the fracture permeability and aperture increase. This is largely because the permeability of the country rock does not increase significantly. While this limits the fluid flux through the system, it does not impede karstification. At later stages, forced convection and buoyant convection effects arise in both models due to the increased permeability of the evolving fracture system. Our results suggest that there is s strong tendency for buoyant convection cells to form under a wide range of conditions. A modified Rayleigh number provides a unified quantitative criterion for the onset of buoyant convection across all cases considered. Once buoyant convection cells are set up, dissolution is sustained in the upward flow portions of the cells, while precipitation occurs in the regions of downward flow. We discuss the implications of this type of flow pattern for the formation of hot springs and mazework caves, both of which are characteristic of hypogene karst environments. We also investigate the sensitivity of karst evolution to various physical and geochemical factors.

Early-stage hypogene karstification in a mountain hydrologic system: A coupled thermohydrochemical model incorporating buoyant convection, 2013, Chaudhuri A. , Rajaram H. , Viswanathan H

The early stage of hypogene karstification is investigated using a coupled thermohydrochemical model of a mountain hydrologic system, in which water enters along a water table and descends to significant depth (_1 km) before ascending through a central high-permeability fracture. The model incorporates reactive alteration driven by dissolution/ precipitation of limestone in a carbonic acid system, due to both temperature- and pressuredependent solubility, and kinetics. Simulations were carried out for homogeneous and heterogeneous initial fracture aperture fields, using the FEHM (Finite Element Heat and Mass Transfer) code. Initially, retrograde solubility is the dominant mechanism of fracture aperture growth. As the fracture transmissivity increases, a critical Rayleigh number value is exceeded at some stage. Buoyant convection is then initiated and controls the evolution of the system thereafter. For an initially homogeneous fracture aperture field, deep well-organized buoyant convection rolls form. For initially heterogeneous aperture fields, preferential flow suppresses large buoyant convection rolls, although a large number of smaller rolls form. Even after the onset of buoyant convection, dissolution in the fracture is sustained along upward flow paths by retrograde solubility and by additional ‘‘mixing corrosion’’ effects closer to the surface. Aperture growth patterns in the fracture are very different from those observed in simulations of epigenic karst systems, and retain imprints of both buoyant convection and preferential flow. Both retrograde solubility and buoyant convection contribute to these differences. The paper demonstrates the potential value of coupled models as tools for understanding the evolution and behavior of hypogene karst systems.