bluuebunny/crossref_metadata_2025_split huggingface dataset:
Is the water still hot? Sustainability and the thermal springs at Bath, England
Authors: Atkinson T. C. , Davison R. M. 
Published: September 2007

Abstract
The hot springs at Bath are the largest natural thermal source in Britain. Sustainable use of the waters for a spa requires maintenance of their temperature and flow rate. Together with smaller springs at Hotwells, Bristol, they form the outflow from a regional thermal aquifer that occurs where the Carboniferous Limestone is buried at depths > 2.7 km in the Bristol-Bath structural basin. The aquifer is recharged via limestone outcrops forming the south and west portions of the basin rim. Current knowledge of the basin’s structure is reviewed, and important uncertainties identified concerning the hydrogeological role of thrust faults which may cut the limestone at depth. A simple numerical model is used to determine the possible influence of thrusts upon groundwater flow within the thermal aquifer. Comparison of the modelled flow patterns with geochemical data and structure contours eliminates the hypothesis that thrusts completely disrupt the continuity of the aquifer. The most successful model is used to simulate the possible impact of dewatering by large quarries at the limestone outcrops north and south of Bath. Substantial reductions in modelled flow at Bath result from proposed dewatering in the eastern Mendips, although the steady-state approach adopted has severe limitations in that it does not take account of the incremental staging of actual dewatering, nor allow for partial restitution of groundwater levels. The geological uncertainties highlighted by the modelling could be addressed by future research into the effect of thrusts on the continuity of the Carboniferous Limestone. More refined modelling to predict the timing of possible impacts of quarry dewatering will require measurements of the storativity of the thermal aquifer.
Institutional development for sustainable groundwater management — an Arabian perspective
Authors: Young M.E. 
Published: September 2007

Abstract
In the Arabian Peninsula, hydrogeological and engineering solutions have failed to solve the severe and worsening problem of unsustainable groundwater abstraction, which threatens rural environments and livelihoods. Conventional western fiscal and regulatory measures to reduce abstractions seem to be impracticable in the present institutional and social contexts. In the region, groundwater rights without volume limitations are distributed mostly among numerous private well owners, and individual interests predominate over a communal imperative for aquifer sustainability. The solution may lie more in modifying the institutional context than in attempting to introduce official controls. This would involve the decentralization of water resources management to a basin or aquifer level and the development of local users associations. Water users associations could improve users’ understanding of local hydrological limitations, promote conservation among irrigators, and cooperatively develop sustainable strategies and rules, which might ultimately include tradable rights and quotas. Government subsidies and incentives are necessary. Essential components of this participatory approach are strong leadership at national and local levels, the active engagement and leadership of Islamic institutions, and the use of modern communication methods.
Incorporation of groundwater modelling in the sustainable management of groundwater resources
Authors: Hulme P. , Fletcher S. , Brown L. 
Published: September 2007

Abstract
Numerical groundwater models have been used by the Environment Agency and its predecessors for over 30 years to help understand the behaviour of aquifer systems and as one of the tools to help manage groundwater resources effectively. The Agency has recently reviewed the past use of distributed numerical models with a view to improving their utilization for groundwater resource management. This is particularly important due to the changes in groundwater management strategies that will occur as a consequence of the new European Union Water Framework Directive. The review has highlighted a number of areas where changes are desirable. Three in particular are the role and importance of the conceptual model, the requirement for a nationally coordinated programme of modelling and the need to develop further the Agency’s in-house modelling expertise. The Agency is currently developing proposals in these and other areas as part of a Research and Development project.
Groundwater sustainability and water resources planning for the East Midlands Resource Zone
Authors: Hudson M. 
Published: September 2007

Abstract

The East Midlands Resource Zone is one of three water resource zones identified by Severn Trent Water in its recent Water Resources Plan, submitted to the Environment Agency. The public water supply to this resource zone is derived from a complex mix of surface and ground water sources, and supplies nearly 3 million people. The most significant aquifer in the East Midlands is the Nottinghamshire Sherwood Sandstone which supplies approximately one quarter of the deployable output for the resource zone (some 200 Ml d
−1
). This aquifer is over-licensed and historically abstraction has exceeded the long-term average recharge. Severn Trent Water has agreed reductions in groundwater licences from this aquifer; however more reductions are targeted by the Environment Agency following its recent reassessment of resources and the introduction of the ‘environmental fraction’. In order to meet the existing resource shortfall and the continuing pressure to reduce abstraction licences, Severn Trent Water propose to support its new surface water abstraction on the River Trent by developing groundwater resources beneath the City of Birmingham. Significant further work is required by water industry regulators and Severn Trent to resolve the projected long-term supply deficit.
The High Plains Aquifer, USA: groundwater development and sustainability
Authors: Dennehy K. F. , Litke D. W. , McMahon P. B. 
Published: September 2007

Abstract
The High Plains Aquifer, located in the United States, is one of the largest freshwater aquifers in the world and is threatened by continued decline in water levels and deteriorating water quality. Understanding the physical and cultural features of this area is essential to assessing the factors that affect this groundwater resource. About 270f the irrigated land in the United States overlies this aquifer, which yields about 300f the nation’s groundwater used for irrigation of crops including wheat, corn, sorghum, cotton and alfalfa. In addition, the aquifer provides drinking water to 820f the 2.3 million people who live within the aquifer boundary. The High Plains Aquifer has been significantly impacted by human activities. Groundwater withdrawals from the aquifer exceed recharge in many areas, resulting in substantial declines in groundwater level. Residents once believed that the aquifer was an unlimited resource of high-quality water, but they now face the prospect that much of the water may be gone in the near future. Also, agricultural chemicals are affecting the groundwater quality. Increasing concentrations of nitrate and salinity can first impair the use of the water for public supply and then affect its suitability for irrigation. A variety of technical and institutional measures are currently being planned and implemented across the aquifer area in an attempt to sustain this groundwater resource for future generations. However, because groundwater withdrawals remain high and water quality impairments are becoming more commonplace, the sustainability of the High Plains Aquifer is uncertain.
Sustainable groundwater resources in a hard-rock island aquifer — the Channel Island of Guernsey
Authors: Robins N. S. , Griffiths K. J. , Merrin P. D. , Darling W.G. 
Published: September 2007

Abstract

The annual volume of water in the Guernsey public supply, which derives largely from surface storage, is approximately 5 Mm
3
. Additional abstraction from private surface and groundwater sources amounts to a further 1.5 Mm
3
. A shallow weathered zone in ancient crystalline metamorphic rocks forms the main aquifer, and this has a significant resource potential in maintaining baseflow to streams. The average annual water budget for the island is 831 mm rainfall, which supports 613 mm potential evapotranspiration, 90 mm surface runoff and 128 mm groundwater recharge. These figures contrast with a poor rainfall year in which infiltration may be zero; the annual variation in rainfall from the long-term mean is often considerable. Annual rainfall has also been declining on the island since the 1940s, and although Guernsey has survived droughts in the past it may be less able to do so in the future. Groundwater on the island is moderately mineralized, but over half of the 21 samples collected recently contained nitrate at concentrations greater than the EU maximum admissible concentration 11.3 mg-N l
−1
. Some of the nitrate may derive from leaking cesspits, but past application of nitrogenous fertilizer to cultivated land accounts for the major component. Attempts at groundwater dating by analysis of chlorofluorocarbon species at a small number of sites was hindered by contamination, although much of the water sampled is apparently young, and recently recharged. The long-term sustainability of the shallow island aquifer and its associated surface waters requires careful husbanding to protect it from conflicting land use interests and water demands.
Groundwater quality in the Valigamam region of the Jaffna Peninsula, Sri Lanka
Authors: Rajasooriyar L. , Mathavan V. , Dharmagunawardhane H. A , Nandakumar V. 
Published: September 2007

Abstract
The Valigamam region is underlain by a Miocene limestone formation and a highly porous soil cover. The region is totally dependent on groundwater to meet its agricultural, industrial and domestic needs, since other sources of water are seasonal. Recharge from rainfall is limited by high run-off and evapotranspirational losses. The region experiences water supply problems due to high concentrations of chloride, total hardness and nitrate in groundwater. The spatial distribution of chloride varies from year to year, with maximum concentrations experienced during or after the wet season. The major factor explaining high chloride concentrations is the excessive extraction of groundwater that results in saline intrusion from the sea or lagoonal areas. In a large proportion of wells sampled for nitrate, levels exceed the WHO standard due to intensive agricultural practices involving very high inputs of artificial and natural fertilizers and the improper construction of latrine soakaway pits. To improve groundwater quality in the Jaffna Peninsula will require controls on the location of new wells, a revision of existing and future pumping rates and a change in agricultural practices. It is imperative that future work in the region should focus on combining groundwater management and sustainable agricultural practice.
Will reductions in groundwater abstractions improve low river flows?
Authors: Rushton K. R. 
Published: September 2007

Abstract
It is a commonly held view that a reduction in groundwater abstractions in many heavily exploited aquifers is likely to improve low flows in rivers. In most aquifers, but especially in chalk and limestone aquifers, the improvement in flows may only be small compared with the reduction in abstraction. Using conceptual and numerical models, the relevant flow processes in chalk and limestone aquifers are examined with special reference to the impact of pumped boreholes on stream and river flows under conditions of differing transmissivities resulting from high or low groundwater heads. The key response is that much of the winter recharge is lost to high winter river flows with only a small proportion of the recharge being stored in the aquifer and available in the summer. Consequently, the low summer river flows, which depend primarily on the areas local to the rivers, may not be strongly influenced by pumped boreholes unless these are close to the rivers. Case studies are used to illustrate the discussion.
A probabilistic management system to optimize the use of urban groundwater
Authors: Davison R. M. , Prabnarong P. , Whittaker J. J. , Lerner D. N. 
Published: September 2007

Abstract
Urban groundwater is an underused resource mostly due to the perceived risk of contamination; conversely rural groundwater is being over-exploited. To enable urban groundwater to be utilized effectively a probabilistic water management tool has been developed. The management tool combines three models to identify the best use for water pumped from a user-defined location. The probabilistic catchment zone model determines the spatial distribution of the probability that water originating from a given point in the aquifer reaches the pumping well. The land-use model then identifies the potential contaminant sources in this region from a large set of GIS-based coverages and databases. The contaminant source data are passed to a pollution risk model that calculates the probability distribution for the concentration of a contaminant at the pumped borehole. Initial model validation using contaminant concentrations from two sites shows the model fits the available field data. These case studies show there is risk from chlorinated solvents but little risk from the BTEX compounds.
A brief overview of eruptions from ice-covered and ice-capped volcanic systems in Iceland during the past 11 centuries: frequency, periodicity and implications
Authors: Larsen Gudrún 
Published: September 2007

Abstract
Eruptions from partly ice-covered and ice-capped volcanic systems constitute nearly 60% of all known historical (i.e. in the past 11 centuries) eruptions in Iceland. Since the fourteenth century such eruptions have been reported in contemporary or near-contemporary documents. At least 120 historical eruptions have broken through the ice on the glaciated parts of five volcanic systems and have left tephra layers in ice and soil, or been recorded at the time. An unknown number of eruptions did not breach the overlying ice and left no record at all. Beginning as subglacial eruptions, most eruptions break through the ice in minutes, hours or days and can last from a few days to several months. A single vent or the whole length of a fissure may then emerge to emit highly-fragmented tephra in hydromagmatic explosions of varying strength. The volume of airborne tephra varies by at least four orders of magnitude with dispersal range varying from near-vent to transatlantic. In most of the eruptions the magma was of basaltic composition. Eruption frequency is highest within the Grímsvötn system where up to seven eruptions every 40 years have occurred during peaks of activity and at least 70 eruptions over historical time. The observed pattern of temporally and spatially close eruptions, separated by periods of low or no activity, leaves open the question whether pre-Holocene deposits of several closely spaced subglacial eruptions can be securely distinguished from those formed in a single subglacial eruption.
Architecture and evolution of hydrovolcanic deltas in Marie Byrd Land, Antarctica
Authors: Le Masurier W. E. 
Published: September 2007

Abstract
The Marie Byrd Land volcanic province is a late Cenozoic alkaline basalt-trachyte volcanic field on the Pacific coast of West Antarctica. Most of these volcanoes are partially buried beneath the West Antarctic ice sheet, but in some, a combination of tectonic uplift and lowering of ice level has exposed basal hydrovolcanic sections produced by eruptions in an englacial environment. Some of the largest and best preserved hydrovolcanic structures are delta-like in form, with gentle distal slopes, and foreset bedded deposits composed of hyaloclastites, pillow breccias, pillow lavas, subaerial flows and air fall tephras. Three broad categories of processes related to delta evolution are described here; (1) flow of lava from a subaerial to an englacial environment; (2) intrusion of dykes and sills; and (3) edifice settling, which includes a variety of down-slope movement phenomena. This paper focuses on documenting post-depositional structures that are superbly exposed in these deltas. It describes the apparently province-wide lack of pillow lava cores in Marie Byrd Land englacial volcanoes, and factors that may be related to this anomaly, and it describes characteristics of hyaloclastites that are relevant to future glaciological, sedimentological and geophysical studies of the West Antarctic ice sheet.
Lithofacies analysis and
40
Ar/
39
Ar geochronology of ice-volcano interactions at Mt. Murphy and the Crary Mountains, Marie Byrd Land, Antarctica
Authors: Wilch Thomas I. , McIntosh William C. 
Published: September 2007

Abstract

Palaeoenvironmental reconstructions and
40
Ar/
39
Ar geochronology of volcanism at Mt. Murphy and the Crary Mountains in eastern Marie Byrd Land (MBL), West Antarctica, provide records of changing ice levels of the West Antarctic Ice Sheet (WAIS) since the late Miocene. Interpretations of eruptive and depositional environments are based on lithofacies studies and indicate whether the volcanoes erupted below, near or above the level of the ice sheet. Seventy-seven new
40
Ar/
39
Ar dates offer a precise chronological frame-work for the ice volcanic history.

Late Miocene (9–8 Ma) basal volcanic sequences at Mt. Murphy and the Crary Mountains (Mt. Rees and Mt. Steere) exhibit fluctuations between ‘wet’ ice-contact lithofacies and ‘dry’ subaerial lithofacies. The ‘wet’ lithofacies include pillow lava and hyaloclastite breccia; the ‘dry’ lithofacies include massive and deuterically oxidized lava and associated welded breccia deposits. The sequences at Mt. Murphy include several erosion surfaces and tillites, which are inferred to represent fluctuations in the WAIS. At Mt. Rees and Mt. Steere, the alternating lithofacies form the constructional slopes of the volcano and are inferred to represent interactions with local slope ice that occurred above the level of the regional ice sheet.

The Miocene to Pleistocene volcanic history of the area provides a proxy record of ice-level changes in West Antarctica, with the following three major conclusions. First, the oldest evidence for a large-scale WAIS is from Late Miocene (
c.
9 Ma) glaciovolcanic sequences at Mt. Murphy and several other sites in Marie Byrd Land. The combined Mt. Murphy and Crary Mountains records indicate that ice-level expansions of the WAIS were more extensive at coastal sites than at inland sites. Second, the present-day WAIS appears to be in a near maximum configuration that has existed at several times since 9 Ma but was rarely exceeded. Finally, a significant expansion of the WAIS above its present-day level occurred at 590 ± 15 ka, when ice levels were 550 m higher at the coastal volcano, Mt. Murphy.
Layered, massive and thin sediments on Mars: possible Late Noachian to Late Amazonian tephra?
Authors: Chapman Mary G. 
Published: September 2007

Abstract
Data from instruments on the currently orbiting Mars Global Surveyor (MGS) suggest that as an alternative interpretation to lacustrine deposits, widespread sediments on Mars may be tephra deposits of variable age, formed in part by volcano-ice interactions. The materials are often associated with outcrops of mapped geological units that have each been previously interpreted as volcanic ash deposits with identified, but unconfirmed possible volcanic vents. Spectral investigation indicates that although some outcrops are basaltic, many show moderate to high concentrations of andesite, a composition at which large explosive eruptions may be possible. In addition, many outcrops are in areas suspected to be water/ice rich. On Earth, magma and groundwater can react to create violent explosive eruptions. Observations from MGS support a pyroclastic mechanism of deposition and show some morphologies consistent with volcano-ice interactions, including subaqueous eruptions. Perhaps MGS data are finally producing more definitive evidence of the widespread tephra that were predicted to be likely in the reduced atmospheric pressure of Mars.
Geochemical and mineralogical analyses of palagonitic tuffs and altered rinds of pillow basalts in Iceland and applications to Mars
Authors: Bishop Janice L. , Schiffman P. , Southard R. 
Published: September 2007

Abstract
Samples of altered pillow basalts and hyalotuffs were collected from a volcanic tuya and hyaloclastite ridge in western Iceland. Altered basaltic material from regions such as Hlöðufell tuya and Thórólfsfell ridge may be similar to the altered basaltic surface fines on Mars. Geochemical and mineralogical analyses have been performed on the Icelandic samples in order to characterize the properties that distinguish palagonitization from other forms of low temperature alteration in this environment. Major elements were measured using an electron microprobe and mienralogy was determined through X-ray diffraction and visible-infrared reflectance spectroscopy. The primary focus in this study was on the <2 μm size fractions of the Hlöðufell altered pillow basalt and Thórólfsfell palagonitic tuff samples. Both volcanic alteration products contain at least some smectite and serpentine clay minerals, as well as poorly crystalline layer silicates. The palagonitic tuff contains more crystalline clay minerals, fewer nanophase iron oxides/oxyhydroxides, and has a higher A1/Fe ratio compared to the altered pillow basalt. Spectra of the <2 μm fractions of both Icelandic samples share similarities with the extended visible region spectra of the bright martian soils measured by Pathfinder and the infrared spectra of the martian dust measured by spectrometers on the Mariner missions.
Freeze-thaw cycles and their influence on marble deterioration: a long-term experiment
Authors: Ondrasina Josef , Kirchner Dirk , Siegesmund Siegfried 
Published: September 2007

Abstract
The deterioration of three marbles (Palissandro, Sterzing and Carrara) differing in composition and rock fabric has been studied using measurements of the thermal dilatation in the temperature range from −40°C up to 60°C. A long-term freeze-thaw experiment was performed to characterize the frost weathering via Young’s modulus. The results show that the combined effect of heating and cooling under dry and water-saturated conditions significantly influences the material properties. The thermal dilatation and its anisotropy can be explained by the crystallographic preferred orientation of calcite and dolomite as well as with the thermal expansion behaviour of these minerals. The residual strain, i.e. the permanent length change, after thermal treatment is different for the investigated samples and less pronounced for the dolomitic marble from Palissandro. The hygric expansion is of only minor importance and weak in the phlogopite-bearing Palissandro sample within the direction parallel to the foliation.
Fresh and artificially weathered marbles were exposed to 204 freeze-thaw cycles. The Young’s modulus for the Carrara marble decreases from 55 GPa to 28 GPa while the porosity increases from 0.25% to 0.62%. The effect on the Palissandro and the calcitic Sterzing marbles is less pronounced while the artificially weathered ones clearly exhibit a drastic reduction in Young’s modulus.
The progressive loss in strength is caused by progressive microfracturing or the loss of cohesion along grain boundaries due to the crystallization pressure of ice growth. The experimental data along with existing theoretical models lead to the conclusion that the physical weathering of marble is influenced by cooling and heating under mid-European climatic conditions.