The UK is highly variable in terms of water supply and demand. A lot of the rainfall received by the UK falls in the North and West, whereas most people live in the South East. This means that the North and West of the British Isles are WATER SURPLUS (areas that have more water than is needed by the population) areas, whilst the south east is a water shortage area (where demand can exceed supply).
The North and the West receive more rainfall because the bulk of our weather comes from the South West with our prevailing wind. This brings moist air because the air is warm and has travelled a long way over the Atlantic Ocean. The wet areas also coincide with our highland areas, as the wet incoming air is forced to rise over these hills, and as it does so it cools, condenses and forms clouds and then rain. These patterns are clearly visible on the maps opposite:
Figure 8 - UK precipitation
People in the UK use a lot of water, they use on average of 175 litres of water per day. This contrasts to just 83 litres in Bangladesh. Only 4percent of the drinkable water in the UK is actually drunk. The rest is used for other uses such as toilet flushing, washing clothes, or cleansing. The demands on our water in the UK have also gone up by 70% since 1985, this is because;
1. The UK population has increased a lot over that time period.
2. Personal habits have changed, people shower more regularly whereas people in the past would have had less frequent baths, often sharing the water with family members.
3. People are wealthier so have more water intensive machines such as dishwashers, washing machines and even power washers.
4. Farm uses have gone up as irrigation systems improve and consumers demand out of season food which needs watering in greenhouses.
5. Industrial uses of water have increased, as has our use of water in producing electricity.
Areas of the UK that suffer from severe water shortages are said to be under water stress. The UK can have unreliable rainfall and during these water stress periods it has been known for hosepipe bans to be put in place and even for standpipes to be put into streets to limit water use.
Figure 9 - population density of British Isles - Contains Ordnance Survey data © Crown copyright and database right [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons)
Water transfer schemes
To combat these issues, we have several water transfer schemes to move water from areas of surplus to areas of demand. Water transfer schemes attempt to make up for water shortages by constructing elaborate systems of canals, pipes, and dredging over long distances to transport water from one river basin to another. More large-scale transfers have been planned to meet future demands but are controversial. The schemes would cost a lot and cause large scale environmental disruption. The schemes can be seen on the map and one suggested scheme would move water from Kielder Water in Northumberland to the reservoirs around London, over 350 miles away.
Kielder water is a good example of a current LOCAL water transfer scheme. Water is trapped behind a dam in North West Northumberland then moved by pipe and rivers into the Derwent, River Wear and River Tees to supply the major settlements along the north east coast such as Newcastle and Middlesbrough.
Figure 10 - England and Wales water transfer schemes