Further description:- United Kingdom  Groundwater processes 

Glossary Entry:- United Kingdom  Groundwater processes
An introduction to the physical, chemical and biological processes that occur in groundwater 
Overview
Groundwater is an essential part of the natural water cycle. It forms the largest available store 
of fresh water in the UK. However, it is a hidden asset, out of sight and all too often out of mind. This
store of groundwater comes mostly from rainfall that has filtered down through the ground. Providing
it is not pumped directly out of the ground, for example for the public water supply, groundwater eventually
discharges into surface waters. Here it supports river flows, and maintains ecosystems. It is the
primary source of water for rivers and lakes in summer or at times of drought. Groundwater is therefore
important to wildlife. Groundwater is an important strategic resource. Three quarters of all the groundwater pumped
from boreholes or taken from springs is used for mains water supply. It directly supplies nearly a
third of the drinking water in the UK.
1. General Approach
Gravity is the main force behind groundwater flow. Groundwater flows mostly through the interconnected 
voids in rock. These may be the pore spaces between the grains in a rock, or cracks and fissures. The
total volume of the pore space is known as the porosity. For the rock to be permeable, the void spaces
must be interconnected, so that water can flow between them. The hydraulic gradient is the slope of the water table. It governs the direction of groundwater
flow. The volume of flow through an aquifer is related to the hydraulic gradient and the hydraulic
conductivity or permeability of the rock. The speed of flow is related to hydraulic conductivity,
hydraulic gradient and effective porosity. Darcys Law relates the volume of discharge through an aquifer to the hydraulic gradient and the
hydraulic conductivity Q = k i a Q = discharge (m3/d), k = hydraulic conductivity (m/d), i = hydraulic gradient, a = cross sectional area of flow (m2) Flow velocity v = k i /n v = velocity in m/d n = effective porosity Intergranular flow occurs when water moves between the grains in rock, for example in a sand or a
sandstone. However, in limestones and many hard rocks, most flow is along cracks and fissures.
This is called fissure flow and is usually significantly faster than intergranular flow. In dual
porosity aquifers, such as the Chalk, the rock mass between the larger fissures can hold considerable
volumes of water. Water flows quickly in the fissures between the rock mass, but intergranular flow
in the matrix is relatively slow. However, eventually a proportion of the water in the matrix is released
from storage. Most rivers derive their flows from both surface run-off and groundwater discharge. Surface run-off
from impermeable ground occurs mainly in winter, is intermittent and is of relatively short duration.
In summer and autumn, when river flows are lower, much of the baseflow is groundwater. There is a zone around a watercourse where surface water and groundwater interact. This is known
as the hyporheic zone. This is a zone where biological and geochemical activity are often enhanced
and where some pollutants may be attenuated. Groundwater can be contaminated by a wide range of naturally occurring substances as well as by
mans activities. In most circumstances, the overlying soils and rocks naturally protect aquifers.
However when groundwater pollution does occur it can go unnoticed for long periods. This is because
the pollutants soak into the ground and disappear from view. Pollution may only become apparent much
later V when, for example, the groundwater quality at an abstraction borehole is affected, or when
contaminated baseflow has a noticeable effect on the chemical quality or ecology of a watercourse.
Because of this time lag, a large volume of aquifer may become polluted before the impacts are readily
noticeable. The potential for groundwater pollution increases greatly if the overlying layers
are removed or bypassed, for example, by quarrying or sinking a borehole for private water supply.
 
2. Policy and Regulation
2.1 Policy
A series of guiding principles are used in the UK to ensure a consistent approach to the assessment 
and management of water resources. These are: h To secure the proper use of water resources for all purposes, including environmental need.
h To protect the environment by: - identifying a minimum flow or groundwater level below which abstraction may be curtailed or
flows augmented; - protecting flow and water-level variability across the full range of seasonal regimes from
low to high water flow/level conditions; - protecting the critical aspects of the water environment including, where relevant, habitats
that are dependent upon river flows or water levels; - recognising that some watercourses or wetlands are more sensitive than others to the impact
of flow or level changes. h To ensure no reduction in existing protected rights. h To protect the interests of other legitimate river users. h To take account of existing and future local requirements that are currently not considered.
These could be protecting or changing flows from rivers into estuaries in order to provide protection
for the estuarine environment. h To take account of water quality considerations throughout the catchment in both surface waters
and groundwater. Groundwater quality is difficult to manage. Land use in the United Kingdom is intensive, with many
potential sources of pollution. Also, the hydrogeology is highly variable. The approach to groundwater
quality protection reflects the requirements of prevailing EU legislation, such as the Groundwater,
Nitrates and Plants Protection Products Directives. Wherever possible, risk-based methods are
used to control releases of pollutants. A combination of legislative controls and influencing measures
has been and will be necessary to achieve the objective of protecting groundwater resources.
 
2.2 Regulation
The Groundwater Directive (80/68/EEC) requires Member States to:  
h prevent the entry of List I substances (the most hazardous) to groundwater;   
h limit the pollution of groundwater by List II substances.   
  
Various pieces of domestic legislation implement these EU requirements. The regulators operate 
a system of permits for intentional discharges and disposals, and control other potentially polluting
activities by measures such as Notices and Codes of Good Practice. Nitrate is not a listed substance under the Groundwater Directive. However, the Nitrates Directive
controls nitrate pollution from agricultural sources. In the United Kingdom Nitrate Vulnerable
Zones have been identified where action plans are used to control nitrate releases. The Biocides and Plant Protection Products Directives restrict the marketing and use of substances
such as pesticides and herbicides. As existing and new products are reviewed for their pollution
risks, this is becoming an increasingly effective way of protecting groundwater. The Water Framework Directive (2000/60/EC) (EC 2000) came into force in December 2000. The Directive
will change the way water is protected and managed. It establishes a new, integrated approach to the
protection, improvement and sustainable use of Europes rivers, lakes, estuaries, coastal waters
and groundwater. The Directive emphasises the need for sustainable development, and encourages
the development of sustainable solutions to water management through the active involvement of
everyone involved in both technical interpretation and implementation. The Directive will be implemented in phases, leading up to the publication of the first River Basin
Management Plans (RBMP) in December 2009. The Directive introduces two key changes to the way the
water environment must be managed. Firstly, it aims to: h protect the water environment and water users from the effects of pollution from dangerous substances;
h introduce new, broader ecological objectives.
 
3. Funding
Site Project Funding
Not relevant 
 
R&D funding
Soil Protection
Research Type: Applied

Topics: Brownfields Contaminated land, Contaminated land overview Contaminated land, Remediation options, Remediation options overview Groundwater protection, Groundwater protection overview Soil, Soil Overview

Submitted by: Maike Hauschild  Who does what?

Full Details |


Soil Biodiversity Programme
Research Type: Basic

Topics: Brownfields Contaminated land, Contaminated land overview Contaminated land, funding Soil, Soil Overview

Submitted by: Maike Hauschild  Who does what?

Full Details |


URGENT (Urban Regeneration and the Environment)
Research Type: Basic

Topics: Brownfields Contaminated land, Contaminated land overview Contaminated land, funding Groundwater protection, Groundwater protection overview Soil, Soil Overview

Submitted by: Maike Hauschild  Who does what?

Full Details |


'Infrastructure and Environment' programme and 'Engineering' programme
Research Type: Basic

Topics: Engineering, Infrastructure and Environment, Brownfields, Contaminated land, Groundwater protection, Funding, Brownfields Contaminated land, Contaminated land overview Contaminated land, funding Groundwater protection, Groundwater protection overview

Submitted by: Maike Hauschild  Who does what?

Full Details |


Bioremediation LINK Programme
Research Type: Applied, Basic

Topics: (1) To understand and exploit natural attenuation in groundwater and soil (demonstration, modelling, prediction, definition of operating window). (2) To improve engineered in-situ bioremediation, interfacing microbiology with engineering and hydrogeology; dealing with heterogeneity, improved process control and optimisation. (3) To translate the results of laboratory studies into the field (scale-up). (4) To position bioremediation within a risk management framework - bioavailability, risk-based end points and residue behaviour. (5) To develop the ability to monitor in-situ microbial processes. (6) To understand the constraints on in-situ microbial processes. (7) To integrate bioremediation with other technologies. (8) To quantify human health impacts of bioremediation and develop surrogate testing. (9) To address socio-economic issues- perception of bioremediation technologies and decision-support mechanisms.

Submitted by: Professor Paul Bardos  Who does what?

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Land Contamination
Research Type: Applied

Topics: site assessment for land contamination, decision support tools for risk management, remediation of contaminated soils, sediments, and groundwater, Brownfields Contaminated land, Contaminated land overview Contaminated land, funding Groundwater protection, Groundwater protection overview

Submitted by: Maike Hauschild  Who does what?

Full Details |


Defra Web Page on: Contaminated Land - funding
Research Type: Demonstration

Topics: There are several measures which support the clean up of contaminated land, and these are described on this web page

Submitted by: Professor Paul Bardos  Who does what?

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Market Information
Not relevant 
 
4: Management tools / decision support and guidance

No further information available

5. Authors


 
    
6. Acknowledgements