There are currently few reliable data available for the concentrations of trace elements in
Scottish groundwaters. A new project Baseline Scotland, jointly funded by the British
Geological Survey (BGS) and the Scottish Environment Protection Agency (SEPA), seeks to
improve the data availability and general understanding of the chemistry of Scotland’s
groundwater. However, this is a major undertaking and these new data will take several years
to collect and interpret across the whole of Scotland.
In the interim, SEPA have asked BGS to use their existing knowledge and data to give a
rough estimate of where certain elements are more likely to be elevated in groundwater. This
information will be used to help focus future monitoring and give background for Baseline
Scotland. Predicting trace element concentrations is difficult, in part due to lack of
knowledge on the distribution of mineral phases, the reactivity of different minerals and the
geochemical environment, particularly the redox status.
This report scopes the potential scale of naturally elevated trace elements in Scottish
groundwater, in particular those elements that are potentially harmful to health: e.g.
aluminium, arsenic, barium, cadmium, chromium, lead, manganese, nickel, uranium and zinc.
The problems and limitations of prediction are discussed in the report and this work does not
replace a proper assessment based on actual chemical analyses of groundwater.
The method uses information on the geochemistry of the Scottish environment derived from
the most comprehensive geochemical data set for Scotland, the BGS Geochemical Baseline
Survey of the Environment (G-BASE), combined with the limited data available on the
chemistry of Scottish groundwaters. The conditions under which each of the elements can
become elevated in groundwater are discussed and the geological and geochemical
information interpreted to produce a series of maps highlighting areas where each trace
element may be elevated in groundwater relative to the Scottish average.
The maps are based primarily on the 1:625 000 scale bedrock geology map of Scotland. In
order to make the scheme and the maps simple and manageable, we have used the same
numbers to describe the individual rock units (1 to 114) that are usedd on the Geological map
of the UK (Solid Geology): North sheet. Some rock units have been subdivided, and other
small areas highlighted where additional information is known, either from G-BASE or
previous studies.
After assessing the results of the exercise the following conclusions can be drawn:
1. The study has provided a useful summary of geochemical information for trace
elements in Scotland, and detail the conditions in which these elements may become
elevated in groundwater. This provides essential background to the Baseline Scotland
project, which aims to improve the availability of groundwater chemistry data and the
general understanding of the chemistry of Scotland’s groundwater.
2. The predictions can be used as a first pass to help focus and prioritise additional
monitoring and for helping to interpret groundwater chemistry data from different
areas. The predictions are only preliminary and will be modified in the future by
detailed groundwater sampling and interpretation.
There are several caveats:
• For all of the trace elements considered, the lack of available groundwater chemistry
data with detailed analysis of trace elements, and their restricted spatial distribution, means that it is not possible to rigorously test whether the groundwater quality
predictions are accurate or not.
• More groundwater chemistry data are available for three elements, barium, manganese
and zinc, allowing a rudimentary test of the predictive maps. For barium the
prediction appears to work well, but there is poor correlation for zinc. For manganese,
some correlation is evident, but the complexity and variability of local conditions are
such that much variation is observed.
• This approach, using broad, national scale geological and environmental data, cannot
account for the complexity of the controls on groundwater chemistry: i.e. the
heterogeneous nature of the Scottish environment, not least the aquifer mineralogy and
glacial history, and the complex behaviour of trace elements in groundwater,
determined by aspects such as flow pathways, residence times, and the geochemical
environment (for example, oxidising/reducing or acidic/alkaline conditions).
In summary, this approach appears to be a useful first step in trying to estimate the likely
distribution of trace elements in Scottish groundwater, in the absence of much reliable
groundwater quality data. However, only by systematically collecting reliable groundwater
chemistry data, across different aquifers and regions and from different depths, can the
variation in trace elements in groundwater across Scotland be understood. Careful modelling
and interpretation of these new data in the context of the geology and environmental
conditions will help make future predictions of groundwater quality more reliable and provide
reference information for the Water Framework Directive.
Abstract The Dumfries Basin aquifer supports groundwater abstraction for public supply, agriculture and industry. Abstraction is concentrated in the western part of the basin, where falling groundwater levels and deteriorating water quality both reflect the effects of intense pumping. There are two bedrock units: a predominantly breccia-coarse sandstone sequence in the west, interfingering with a predominantly sandstone sequence in the NE and east. The basin is bounded by weakly permeable Lower Palaeozoic rocks, and is largely concealed by variable superficial deposits. Surface water flows onto the basin from the surrounding catchment via the Nith and the Lochar Water and their respective tributaries. Direct rainfall recharge occurs via superficial sands and gravels, especially in the north, and discharge is predominantly to the rivers in the central area rather than the sea. A picture is developing of two main aquifer types within the basin: the high-transmissivity western sector underlain by a fracture-flow system with younger water and active recharge and a high nitrate content, compared with the east where groundwater residence times are longer and the storage capacity is higher.
These notes are designed to accompany the ArcView geographical information system (GIS) format groundwater vulnerability index map produced by the British Geological Survey (BGS) for Fife Council. The map is based on digital geological information for both bedrock and superficial (drift) deposits. It covers the whole of the Fife Council area plus a 3 km ‘buffer zone’ around the landward boundaries to account for peripheral data and allow for more meaningful interpretation.
The purpose of the GIS map is to indicate, in broad terms, the vulnerability of groundwater to pollution. Groundwater is contained within aquifers of various types. Abstractions from these aquifers provide water for potable supplies and various domestic, industrial and agricultural uses. Some highly permeable aquifers are very productive and of regional importance as sources for public water supply; other, less permeable formations, are of local importance for domestic, agricultural and industrial supplies. Groundwater also provides the baseflow to surface watercourses. Groundwater is typically of high quality and often requires little or no treatment before use. However, it is vulnerable to contamination from both diffuse and point source pollutants, from direct discharges into groundwater and indirect discharges into and onto land. Aquifer remediation is difficult, prolonged and expensive: therefore, the prevention of pollution is important.
The approach and classifications used in the production of the groundwater vulnerability index can also be used in the assessment of specific land use practices, proposed developments and land use changes over aquifers where these could have an impact on groundwater quality. More detailed site specific assessment of vulnerability will be required where it is considered that development may have an impact on groundwater quality.
This GIS and printed maps are a compromise between the representation of natural complexity and the simplicity of interpretation at a scale of 1:50,000. This places limitations on the resolution and precision of map information. There is a wide variety of geological strata and potential pollutants, and the vulnerability index classification is, of necessity, generalised. Individual sites and circumstances will always require further and more detailed assessment to determine the specific impact on groundwater resources. The map coverages in the GIS only represent geological conditions (bedrock or superficial) as mapped at their upper surface. Where these formations have been disturbed or removed, for example, during mineral extraction, the vulnerability class may have been changed. Hence, where there is evidence of disturbance, site specific data need to be collected and used to determine the vulnerability of the groundwater.
The overall permeability of each geological unit has been interpreted to produce an index of the vulnerability of groundwater occurring in Fife, and provides a broad-based view of both the vulnerability of groundwater and the location of the more permeable aquifers in Fife. The vulnerability index classification does not follow the methodology devised for an earlier published groundwater vulnerability map (NERC and MLURI 1998). The latter methodology includes an assessment of soil leaching potential, and combines data on superficial geology and soils to produce vulnerability classifications. The other main difference between the two maps is that the new GIS map gives equal weight to bedrock and drift aquifers, whereas on the earlier map the bedrock formation takes precedence if it is highly permeable.
The data used to interpret the groundwater vulnerability index are derived from the 1:50 000 DigMap bedrock and drift geology coverage. The GIS and associated maps should not therefore be used at scales larger than 1:50 000. Locations of thick clays have been interpreted and drawn based on BGS borehole records. Information on water boreholes is derived from the British Geological Survey Scottish Water Borehole database.
Urban planners and developers in some parts of the United Kingdom can now access geodata in an easy-to-retrieve and understandable format.3D attributed geological models and associated GIS outputs developed by the British Geological Survey (BGS) provide a predictive tool for planning site investigations for some of the UK's largest regeneration projects in the Thames and Clyde River catchments.
This report describes field experiments into the groundwater environment around the Virksjőkull
glacier in southeast Iceland, which were carried out between September 2011 and September
2012. The report describes these experiments and presents the resulting data: it is not intended to
provide any interpretations of the data, but to be a record of project activities and field results.
BGS has set up a multidisciplinary observatory at Virkisjokull, which provides an excellent
opportunity to characterise and quantify groundwater in the sandur aquifer and its interaction
with glacial meltwater. For more information on the wider geoscientific research being carried
out at Virkiskjőkull see http://www.bgs.ac.uk/research/glacierMonitoring/home.html. Climate
data, including rainfall, and meltwater river flow data are being collected, and considerable
datasets are being developed related to glacial mass, glacier movement, and surface topography
and geomorphology.
The following groundwater-related activities have been carried out and are reported here:
• In three short field surveys in September 2011, February 2012 and April 2012, the focus
was on:
o Collecting samples of shallow (<1m deep) groundwater, meltwater and ice for
chemistry, stable isotope and residence time analysis
o Testing ground surface permeability on the sandur and the immediate pro-glacial
area.
• In summer 2012, a longer field campaign focussed on:
o Drilling shallow (10-15 m deep) boreholes into the unconsolidated sandur, as
three short transects away from the meltwater river, and testing the boreholes to
measure aquifer permeability
o Drilling two shallow (6-18 m deep) boreholes into volcanic bedrock between the
glacier front and the sandur, to help investigate whether groundwater flow
through the bedrock plays a significant role in glacier drainage.
o Collecting groundwater and additional meltwater samples for chemistry, stable
isotope and residence time analysis
o Installing sensors to monitor groundwater level, temperature and conductivity
throughout the year.
o Hand-constructing very shallow (<1m deep) piezometers to extend the borehole
transects and to investigate the immediate river-groundwater zone
o Further testing of ground surface permeability on the sandur.
These notes are designed to accompany the ArcView geographical information system (GIS)
format groundwater vulnerability index map produced by the British Geological Survey (BGS)
for Moray Council. The map is based on digital geological information for both bedrock and
superficial (drift) deposits. It covers the whole of the Moray Council area plus a ‘buffer zone’
around the landward boundaries to account for peripheral data and allow for more meaningful
interpretation.
The purpose of the GIS map is to indicate, in broad terms, the vulnerability of groundwater to
pollution. Groundwater is contained within aquifers of various types. Abstractions from these
aquifers provide water for potable supplies and various domestic, industrial and agricultural uses.
Some highly permeable aquifers are very productive and of regional importance as sources for
public water supply; other, less permeable formations, are of local importance for domestic,
agricultural and industrial supplies. Groundwater also provides the baseflow to surface
watercourses. Groundwater is typically of high quality and often requires little or no treatment
before use. However, it is vulnerable to contamination from both diffuse and point source
pollutants, from direct discharges into groundwater and indirect discharges into and onto land.
Aquifer remediation is difficult, prolonged and expensive: therefore, the prevention of pollution
is important.
ABSTRACT Characterising the three-dimensional (3D) distribution of hydraulic conductivity and its variability in the shallow subsurface is fundamental to understanding groundwater behaviour and to developing conceptual and numerical groundwater models to manage the subsurface. However, directly measuring in situ hydraulic conductivity can be difficult and expensive and is rarely carried out with sufficient density in urban environments. In this study we model hydraulic conductivity for 603 sites in the unconsolidated Quaternary deposits underlying Glasgow using particle size distribution and density description widely available from geotechnical investigations. Six different models were applied and the MacDonald formula was found to be most applicable in this heterogeneous environment, comparing well with the few available in situ hydraulic conductivity data. The range of the calculated hydraulic conductivity values between the 5th and 95th percentile was 1.56×10 –2 –4.38mday –1 with a median of 2.26×10 –1 mday –1 . These modelled hydraulic conductivity data were used to develop a suite of stochastic 3D simulations conditioned to existing 3D representations of lithology. Ten per cent of the input data were excluded from the modelling process for use in a split-sample validation test, which demonstrated the effectiveness of this approach compared with non-spatial or lithologically unconstrained models. Our spatial model reduces the mean squared error between the estimated and observed values at the excluded data locations over those predicted using a simple homogeneous model by 73 %. The resulting 3D hydraulic conductivity model is of a much higher resolution than would have been possible from using only direct measurements, and will improve understanding of groundwater flow in Glasgow and reduce the spatial uncertainty of hydraulic parameters in groundwater process models. The methodology employed could be replicated in other regions where significant volumes of suitable geotechnical and site investigation data are available to predict ground conditions in areas with complex superficial deposits.
The INSPIRE Directive (2007/2/EC of the European Parliament and of the Council and in force from the 15th May 2007) establishes an infrastructure for spatial information in the European Community. By facilitating the availability and access of spatial (geographic) information, best use can be made of the data for the benefit of a wide variety of users in different sectors and disciplines. Planning and development in Scotland bring together such a broad mix of users of spatial data. Therefore, the INSPIRE Directive has a key role to play in promoting improvements to spatial data infrastructures on which the efficiency and effectiveness of the planning process and successful and sustainable development depend. As a result, the Scottish economy will benefit, especially within the construction sector (which accounted for 6.6% of GDP in 2004, with a £12 billion turnover (www.scotland.gov.uk/Publications/2006/12/19143801/0)), as will society as a whole.
Hydrofracturing of new public water supply boreholes in Precambrian crystalline bedrock in Scotland has increased borehole yields by at least one order of magnitude, and made the difference between borehole abandonment and success. In many upland rural areas of the UK, low-productivity aquifers are an important resource for small public water supplies. Where a borehole in low-productivity crystalline rocks proves too low yielding for its designed purpose, hydrofracturing is a cost-effective means of enhancing yield.
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