Reservoir dogs future water supply
Population growth, climate change, increased consumption: how are future water shortages to be resolved?
Shelter, food and water are three basic human needs. Securing water supply in the UK rests with 27 private water companies.
The largest, Thames Water is planning for a supply problem in the future. Even if it saves the 864.91 Ml (mega litres) a day leaking out of its 19th Century pipes, it still needs a larger supply. It estimates that a London population of over 12 million will face water shortages within 20 years. Their solution will cost £800 million.
What is the problem?
Supply and demand is at the root. Natural population growth in London is expected to grow by 700,000 by 2016. John Prescott has announced plans for 200,000 new homes in the London region. This summer and autumn are proving to be one of the driest ever; suggesting climate change is already having an impact on the UK. Already the Thames region has less rain per capita than Istanbul or Madrid. This combines to produce a pattern of increasing demand, and reduced supply.
What is the plan?
Thames Water is looking at the possibility of building a reservoir on 3,500 acres of farmland between Abingdon and Wantage in Oxfordshire. This will allow water currently flowing into the Thames to be harnessed for human use. However to build and fill the £600 million reservoir could take 20 years; a more immediate solution is needed to cope with the problem of water shortages owing to a drier climate. Thames Water is proposing a desalinisation plant at Beckton, East London, to allow water from the Thames Estuary to be used.
What is the broader picture?
There are multiple causes and multiple impacts of these proposals. Building the reservoir will mean less pressure on ground water stores that currently used to supplement water supplies. Use of these groundwater stores, however, creates the risk of lowering the water table and causing soils to dry out leading to, among other things, subsidence of buildings, and shrinking of soil (causing cracking of water mains and road surfaces).
Wildlife habitats such as those that have been disappearing over the past 60 years with the mechanisation of, and the chemicals used in, farming, can be created by reservoirs. Slow moving shallow water at the entry point can become a breeding ground for birds and vegetation around the banks can provide animal habitats. The water body itself has potential for water sports as well as for providing drinking water.
Conversely, flooding of farmland means the loss of agricultural production, thus reducing the capacity of the local area to produce food, should we ever return to a localised production system through future changes to the C.A.P. The harvesting of water before it reaches the Thames means there will be a reduction in sediment input not so crucial for the heavily modified river in London - but more important for the tributaries in Oxfordshire. The reservoir itself will require dredging and servicing, necessitating infrastructure improvements the locality. The reservoir could also change fish movements in the Thames.
What are the alternatives?
Another approach to meeting demand could be to reduce it. Instead of investing in infrastructure to provide water, investments could be made to reduce consumption. An example of how water demand from Thames Water was reduced was seen at the Millennium Dome where rainwater runoff from its huge roof was used to flush toilets. Compulsory metering of all water use could increase water consciousness and raise revenue for future investment in sustainable water management. Dishwashers, power showers and other household appliances are all growing in number and using more water maybe manufacturers need be forced to increase efficiency of their products through legislation. Maybe London has or will soon exceed its carrying capacity; maybe we just cant provide enough water sustainable to serve the population.
Whatever is done, the taps cannot run dry in the short or long term, nor must we jeopardise opportunities for future generations.