Controlled Water Supply and Demand Studies of England and Whales Conducted by Water Companies

In the future, climate change in England and Whales will likely cause wetter winters and dryer summers. Along with other factors, the amount of useable water available will likely decrease overall. The amount of water demanded will likely increase overall as well. Charlton and Arnell (2010) assesse the balance of supply and demand in England and Whales from 2009/2010 to 2034/35.  The estimated loss of useable water from 2009–2035 is 520 Megaliteters per day and 475 Ml/day due to climate change. Climate change is shown to likely be the largest impact on water loss with sustainability reductions, or more regulations on water taken, shown as the second largest impact. 37% of the supply-demand water stress predicted is caused by climate change. Demand increase of 620 Ml/day accounts for 56% of the pressure increase. Climate change could have such a high impact, that most companies have agreed that it must be safe guarded against and future plans must be made to access more water in the case of negative climate affects.

–Darien Martin

Charlton, M., Arnell, N. 2010., 2010. Adapting to climate change impacts

on water resources in England—an assessment of draft Water Resources

Management Plans. Global Environmental Change, Human Policy and Dimensions. 21, 238–248.

Twenty-one water companies compiled plans for 2009–2035. Data were gathered from 80 zones, compiled and analyzed to predict the amount of impact climate change would have on water supply, and to compare this magnitude to other calculated impacts. The change in demand was then calculated from 2009/10–2034/35 using 55 of the 80 zones, and compared to supply. Lastly, companies’ plans and options for future were discussed.

England and Whales have wet winters, and dryer summers, when water companies worry about having enough water supply to meet demand.  These data are compiled from 23 companies’ studies, which have been moderated economically by Oftwat, and Environmentally by an The Environmental Agency. This plan was required of each company. Each company surveyed its own resource zone and calculated the supply demand balance in its zone with the same equation: Useable output – climate change impact – sustainability reduction (or diminishing in resource use efficiency) – other reductions – other allowances – process use loss – untreated water export + untreated water import – treated water export + treated water import. Companies used this formula to determine available headroom, the amount of excess supply, which is left unused, which can recharge supplies.

          The three tasks assigned to guide companies with formulating this Water Plan were 1. Calculate river flows and levels of river when it’s replenished in different seasons; 2. Calculate future water data (by plugging groundwater data into a simulation which will predict future output); 3. Calculate future estimates of water demand; 4. Predict future headroom in wet, medium, and dry conditions. Climate change is predicted to cause hotter summers and wetter winters.

          In projections for 2034–35, climate change impact alone caused an increase in fewer than 20% of company resources zones more than 5%. The greatest impact increases were seen in the southeast of up to 15-20% in 4 zones, and 10 –15% in two zones. Small zones were impacted by climate change more generally. Other factors affected supply. The second highest impact change came from reductions of sustainable water use practices. Other affects projected were very marginal in comparison (such as water exports, process losses, and other allowances). This study also showed well that the impact of climate change in changing water supply in 2034–35 was uncertain, but that the amount of impact possible was substantial and should definitely be accounted for in companies’ future plans.

          Water supply was evaluated from present to 2035, with concern to useable output, climate change effect, sustainability reduction, outage allowance, process losses, water export, and water import. The amount of useable water was measured for three scenarios: wet, medium and dry climates. 10% loss of useable water was seen nationally. Fewer than 20% of zones had a reduction of more than 5% water supply. 58% of the water loss projected to be in the southeast of England. The total water loss predicted is equivalent to a large reservoir, holding 21,320 Ml which provides water for 1.65 million people. This poses a danger to England and Whales if they do not plan accordingly.     

In relation to this loss in water, demand is projected to increase 620 Ml/d over the 55 zones. Climate change is the dominant factor in water stress accounting for 407MI/d in these zones. A reduction in the sustainable practices required in England is the second largest impact, causing a loss of 80Ml/d in these regions. It is shown that in the case of a wetter climate scenario, some regions will have an increase in supply in the future, which could reduce the demand-supply pressure, however, this would be irrelevant, because companies would not be able to take this water.

          Possible actions for future water company plans include storage and increased connectivity. Dams would have the capacity to store excess water in the increasingly wetter wet seasons. Companies are starting to make their systems more coherent and connect their grids to flow more smoothly between zones, and correspond more directly to the networks of the water flows themselves. These connections may reduce water use losses.

Charlton and Arnell estimated that Britain would have a loss of 520MI/d of water in the next 25 years. This is 3% of overall useable water supply. The great majority of this reduction prediction will be caused by climate change.

                   In total, future water supply is projected to decrease 1117Ml/d by 2034–35 from climate change, and water companies must adapt. Companies plan to focus on water supply increase. Building more reservoirs, and connecting water systems across companies to make a more coherent grid that coincide with whole river and aquifer systems are options. Charlton and Arnell believe this would build more water resource resilience for England and Whales in dryer summers and other unforeseen circumstances.