Beating the drought
Two consecutive dry winters are to blame for the current drought - the third to have occurred since 1976 - and its impact on water resources in the South-east. With water management now under the public's microscope, Jonathan Reed looks at what can be done to manage the demand for water and maintain available supplies, whilst minimising impacts on the environment.
The current drought has been caused by a lack of rainfall in the South-east over the winters of 2004/05 and 2005/06, and it is regional - Kent and Sussex are the most severely affected areas, although it also affects the Thames catchment and parts of East Anglia.
The lack of winter rainfall has resulted in low recharge, and hence lower than normal groundwater levels. This has reduced baseflow to rivers and means that there is less water available for abstraction from groundwater sources.
Rainfall over the18-month period is about 75% of the long term average. This lack of rainfall is classified by CEH as having a return period of between 1 in 35 and 1 in 50 years.
Rainfall in the South-east returned to average or near average levels during March and April 2006, which allowed some groundwater recharge and an increase in river flows. There was significant rainfall in May, although this was offset by higher temperatures and the start of the growing season, which reduces the quantity of water available to recharge aquifers.
Since the 1976 drought people have grown accustomed to using increased amounts of water in their daily lives. Society is more affluent resulting in more widespread ownership of water using appliances.
Water companies take account of changes in domestic water consumption and increased housing development in their future planning which is to ensure that the available supplies can meet the demand even during drought conditions.
As a drought situation develops there are a number of actions that they can take to constrain demand, starting with appeals to their customers' to reduce water use and leading up to more severe measures that are available under the Water Resources Act.
Water companies work with the Environment Agency (EA), the media and local groups in order to promote demand management.
This often takes the form of providing advice about water efficiency, undertaking audits and providing free repairs to customer supply pipes. A description of the actions people can take to reduce water use in their homes can be seen by visiting www.beatthedrought.com
The first actions that water companies can take are to impose either an unattended hosepipe and sprinkler ban or a full hosepipe ban, and they have the legal right to do this under the Water Industry Act. A hosepipe ban actually only restricts domestic customers from using a hosepipe to wash a car or water a garden.
This leads to some inconsistencies as other activities, such as using a pressure washer to wash a patio, are permitted. Hosepipe bans are currently in force in several areas.
Leakage is undoubtedly a contentious issue, particularly during a drought when water companies ask customers to reduce their water use to conserve resources.
Members of the public see large volumes of water being "wasted" by companies, with little being done about it. Leakage should be minimised, but in reality there is little that can be done during a drought to increase resources by reducing leakage.
The level of leakage that companies are required to meet is controlled through the regulatory framework, whereby companies aim to reduce leakage below the Ofwat defined target level of leakage.
This is usually related to the 'Economic Level of Leakage' (ELL) which is the most justifiable level of leakage in financial, environmental and social terms when compared against the cost of developing other resources.
Water companies can apply for Drought Permits that allow them to change conditions of existing abstraction licences or to abstract water from new sources.
Drought Permits are granted by the EA for a period of up to six months, following which time they can be extended for up to a further six months.
In order for a Drought Permit to be granted, two legal tests must be proved. These are:
- That there has been an exceptional shortage of rain
- A deficiency of supplies of water in any area exists or is threatened.
This report is in effect an Environmental Impact Assessment (EIA) of the proposal, although it is focused on the short-term nature of the Drought Permit.
The EA will often impose conditions on the Drought Permit, for example stipulating when Figor how the abstraction may take place and what monitoring is required.
Over the last year the Environment Agency has granted several Drought
Permits, such as that altering the abstraction from the River Medway to refill Bewl Water.
Drought Orders are Statutory Instruments that are made in England by the
Secretary of State for Environment, Food & Rural Affairs and in Wales by the National Assembly for Wales.
These allow water companies to apply to:
- Vary conditions on abstraction licences or abstract water from new locations
- Prevent others abstracting water
- Change the location of discharges
- Prohibit the non-essential use of water
There are usually public hearings as a result of applications for Drought Orders where objectors put their case in front of an independent inspector, who then reports to the Secretary of State or the National Assembly for Wales.
In March 2006, Mid Kent Water, Sutton & East Surrey Water and Southern Water
all applied for Drought Orders to prohibit the non-essential use of water.
This allows them to ban a number of activities that are specified in the Drought Direction (1991).
These include some business activities such as window cleaning and car washing. Therefore, a non-essential use ban will cause social and economic hardships.
To minimise the potential impact on businesses the companies have developed a phased approach to the implementation of restrictions.
Water companies and the EA produce Drought Plans to set out the actions they will take during a drought.
These include increased monitoring of critical sources as a drought deepens and the implementation of appropriate demand restrictions and resource management options.
Water companies have recently submitted their revised Drought Plans to DEFRA and the National Assembly for Wales.
Most Drought Plans are currently available for public consultation.
Many companies now have access to complex water resource models, which allow them to investigate the potential impacts of a drought on their sources.
This analysis leads to a strategy of how best to deal with the consequences of a drought as timely and appropriate interventions can be identified which can
maximise the benefit of increased abstraction whilst minimising the impact on the environment.
In conclusion, different types of drought have different impacts on resources, all of which must be managed. Drought Permits and Orders to abstract additional water have the potential to impact the water environment at a time when it is already stressed.
Hence drought planning must include both management of demand and prudent and timely use of resources to ensure that impacts on the environment are minimised.
Jonathan Reed is senior engineer at Atkins Water & Environment.
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