Safe enough? Proportionate climate change adaptation in London’s water supply system

London faces increased risk of water shortages in the future due to climate change and population growth if no actions are taken to increase supply or reduce demand, according to a new study led by Edoardo Borgomeo and Jim Hall at the Environmental Change Institute. The research presents a new methodology for water managers to incorporate climate change uncertainties into water resources planning.

Water resources managers have significant experience in planning and operating their systems in the face of hydrological and weather variability. The reality of climate change, however, poses new challenges for water resources managers. Whilst the precise impacts of climate change for temperature, precipitation and water availability remain uncertain, water managers still need to take into account these uncertainties in their water plans. In the UK water companies are now legally obliged to evaluate the impacts of climate-related risks on their systems.

To help water managers address this challenge, this study develops a methodology for incorporating climate change related uncertainties in water resources planning. The methodology uses a risk-based metric to compare different water management options on the basis of their ability to reduce risks of water shortages under continuously changing climate conditions.

This methodology responds to the need in the UK and worldwide for a way of identifying water management investments which are proportionate to the risks the water systems are facing. Supply-side and demand-side management strategies can be compared based on how cost-effective they are at reducing risks to acceptable levels.

The risk-based methodology was applied to the London water supply area to characterise the most important uncertainties and identify water management options that are capable of reducing the harmful impacts of climate change. Results from the study demonstrate that without further supply or demand interventions, the combined effects of climate change and population growth are projected to increase the risk of water shortages in the future in London.

This research, led by Edoardo Borgomeo and Jim Hall, was carried out in partnership with Thames Water and the Environment Agency. The study contributes to the ongoing discussion in the UK water sector on whether the current approach to water resources planning should change for the next round of water resources management plans in 2019.

Reference

Borgomeo, E., Hall, J.W., Fung, F., Watts, G., Colquhoun, K. and Lambert, C. (2014) Risk-based water resources planning: Incorporating probabilistic nonstationary climate uncertainties. Water Resources Research. DOI: 10.1002/2014WR015558