A new paradigm for urban flood design storms accounting for variability in space and time under climate change

The extent and severity of the damage caused by urban floods is a product of both the intensity and duration of the rainfall (variable in space and time) and its interaction with the complex flowpaths of a city, on the surface and below ground (drainage network). Resilient design of urban drainage under climate change is currently blocked by the lack of a realistic design storm methodology. Conventionally, Intensity-Duration-Frequency (IDF) curves based on point rainfall measurements are used in design and such use of single events with standard profiles in time and uniform in space is widely recognised to be unrealistic, as individual storm events in large urban areas show great variation in key properties, and their spatial distribution and sequencing can interact strongly with critical pathways and vulnerable areas in cities. The main objective of this proposed PhD research is therefore to analyse precipitation extremes in a changing climate using high resolution climate model outputs, advanced stochastic modelling methodologies and the CityCAT urban flood modelling system.

This project will develop new ensemble descriptions of storms to be used in multiple hydrodynamic simulations of cities with different characteristics. The new methodology will be developed using real cities, as well as synthetic networks in order to provide a wider range of situations to demonstrate robust design optimisation. The resulting framework will be widely applicable and of interest to water utilities, lead local flood authorities and consultancies.

In this work, high-resolution climate model outputs will be used in order to create a methodology for deriving realistic storm events for a range of cities under climate change. These events then are going to be used to optimize urban drainage design. This will be achieved by creating a framework to run and analyse hydrodynamic simulations from the fully coupled (surface and surface drainage network) hydrodynamic model CityCat. Possible blue-green interventions also be explored.

Graduates from the WRIC programme will produce new knowledge across the disciplinary landscape and graduate to occupy professional roles of influence and authority which require a thorough understanding of the pathways by which knowledge and technology are adopted and put to socially significant use. The people and knowledge delivered through the CDT will improve the efficiency and effectiveness of the nation's >£5bn annual spend on water and water related infrastructure (OFWAT, 2017), improving its resilience and securing its value for society for generations to come. With ambitions to nurture domain experts who can flourish at the interfaces of scientific disciplines and economic/industry sectors, the impact imperative is a significant but stimulating challenge for the WRIC CDT. Our impact strategy seeks to; (i) ensure rapid dissemination of scientific insights, (ii) maximise awareness and uptake of research sponsored through the CDT, and (iii) improve professional and lay understandings of the water infrastructure challenges facing society and the science behind candidate solutions. This strategy has been developed with project and Centre stakeholders so as to leverage additional resources, and maximise impact.
Improving the resilience of water infrastructure systems will be of benefit to a wide range of stakeholders. Given the CDT's bold intention to tackle knowledge gaps at the interfaces between disciplines and problems, new scientific understandings generated through WRIC will be of value to the knowledge users in the public sector (local authorities, regulators) and private sector (utilities, consultancies, technology providers), ultimately benefiting both lives and livelihoods across the UK and beyond. The UK economy will benefit from robust and resilient water infrastructure, in-line with the UK Government's Industrial Strategy for cleaner economic growth, the efficient use of resources, and building a regenerative circular economy. In the next Price Review PR19 (2020-25), water companies will be financially rewarded for implementing enhanced system resilience and innovation. Research outputs from WRIC will enable water companies to be able to meet these demands, alongside ambitious industry targets for zero water and wastewater quality failures, demand reduction and chemical recycling (OFWAT, 2017; UKWIR, 2017). These developments will facilitate inward international investment, development of new technology providers and supply chains, and opportunities for exporting intellectual property and know-how worldwide, further benefiting the UK economy. Project partners, including Thames Water, Severn Trent Water, Atkins, Stantec, Datatecnics also benefit from access to high quality graduates and facilities. Furthermore, regulatory agencies (Environment Agency, Drinking Water Inspectorate) and the European Commission will see benefits from improved compliance to regulations and sustainability agendas (Water Framework Directive 2008/32/EC and Drinking Water Directive 2017/0332(COD)).
The CDT programme will benefit the UK Collaboratorium for Research on Infrastructure and Cities (UKCRIC) government investments (£138M). Sheffield, Cranfield and Newcastle Universities have all received capital grants through UKCRIC to fund industrial scale test facility and observatory facilities to form an Urban Water Hub. The CDT will supply the resources to use and maximise the benefits and outputs from these facilities. Cooperation with other UKCRIC CDTs will help students better understand contemporary challenges for infrastructure and cities will catalyse horizontal innovation transfer and elevate the transformative potential of WRIC graduates.