Exploring regional water transfers to secure future water supply: a case study from the UK

McBride, A. and Durant, M. and Counsell, C. and Ball, A. (2019) Exploring regional water transfers to secure future water supply: a case study from the UK. In: Irish National Hydrology Conference 2019, 19 November 2019, Athlone, Ireland.

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Abstract

Water companies in the UK are required to produce long-term plans of water resources for their supply area every five years, detailing how they will maintain secure and sustainable supplies, taking account of social and environmental impacts as well as economic costs. As a result, the water environment is highly regulated to ensure competing demands are satisfied. Approximately a quarter of the UK population lives in the south-east of the country where six separate water companies supply water. The population of this region is projected to grow at a rate exceeding the national average, with some areas predicted to face water supply deficits in the near future. Therefore, should no action be taken, the demand for water is forecast to increase whilst the availability of water resources decreases due to climate change and the reduction of some licences to improve the freshwater environment. A recent exercise highlighted the very real difficulties that would be faced in implementing existing severe drought response and mitigation measures in practice in response to a drought affecting the south-east. A key conclusion from the WaterUK long term planning framework report was that large-scale inter-regional transfers of water could offer the best value for money. Strategic schemes to transfer water from areas of projected water security to those of projected water scarcity are actively being explored. OFWAT, the financial regulator of the UK water industry, expects a fully informed decision to be made on which scheme, if any, to progress with, by 2022. These potential transfers pose several regulatory, environmental, and operational challenges. For example: How can water companies be confident that the water will be available when they need it?; How can regulators test the scheme without damaging the environment?; How can all stakeholders agree to the data and analytical approaches being used to assess the scheme?. We have undertaken several studies to support the assessment of the feasibility of a transfer of water from reservoirs in the upper reaches of the River Severn in Wales to the south-east via the River Severn and the River Thames. As part of this work, hydrological and water resources models of both catchments were developed for the study area exceeding 20,000 km2. These models brought to light uncertainties across key flow gauging stations and the challenges of operating a scheme in a highly regulated river network. Using these models, and a series of drought libraries developed using both synthetic and stochastic time series, an assessment of the likelihood of coincident drought in both catchments was undertaken. Drought events in the River Thames which would trigger the need requirement for additional resources via a strategic scheme were mapped to the River Severn. The assessment highlighted conditions under which a water supply system with several sources of supply could increase its resilience to drought. To understand the net gain of the scheme, the catchments were divided into key reaches and factors such as attenuation, groundwater-surface water interactions, and travel time were systematically assessed. The results of this study concluded that the key source of uncertainty associated with this strategic scheme were not physical processes, but rather were attributed to how the scheme would be operated and regulated. A scoping phase of work is currently being planned with regulators across the two catchments, water companies, and stakeholders to physically test the scheme. Our presentation will discuss the technical approach, challenges, and results of these studies, as well as an overview of the perspectives of water companies, regulators, and stakeholders.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: Water resource planning, water demand, strategic schemes, water transfer, climate change, drought, United Kingdom
Subjects: Water > Water resources
Divisions: Water
Depositing User: Unnamed user with email i.services@hrwallingford.com
Date Deposited: 02 Apr 2020 09:54
Last Modified: 02 Apr 2020 09:54
URI: http://eprints.hrwallingford.com/id/eprint/1378

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