Climate Adaptation Control Technologies for Urban Spaces (CACTUS)

Climate change is causing, and will continue to cause, more intense precipitation events and greater amplitude of warm and cold temperatures leading to severe flooding, extreme drying, freezing and thawing. This will affect many parts of the urban geo-infrastructure such as shallow foundations, retaining structures, buried utilities, road subbase and railway formations. The costs of damage due to shrink/swell movements on clay soils have resulted in economic losses of over £1.6 billion in the UK during drought years. The novelty of the proposed research is the development of "climate adaptation composite barrier systems" (comprising water holding layers and a capillary barrier) capable of limiting the impact of a changing environment on the geo-infrastructure and hence increasing their engineering sustainability and resilience. Environmental cyclic actions imposed on our infrastructure are governed by soil-plant-atmosphere interaction, which is a coupled thermo-hydro-mechanical problem driven by the atmosphere and influenced by soil type, stress history, stress level, mineralogy, soil-water chemistry and vegetation. Understanding this complex problem requires systematic research and a coherent approach. This proposal describes systematic experimental and numerical modelling studies to understand the response of composite barrier systems, when subjected to extreme weather events and long-term climate changes, and to develop appropriate sustainable adaptation technologies to mitigate potential impacts on urban geo-infrastructure.

The CACTUS project will demonstrate the following contributions to society and the economy:

1. It will demonstrate major economic impact in providing technologies that can reduce the costs to the UK economy of:

(i) Flooding. Flash flooding has become a highly significant economic and social problem in our cities. The project will demonstrate technologies to provide flash flood control measures by increasing the flood holding capacity of soils, thereby reducing runoff of rainwater. The clean-up costs of flooding in the UK in recent years have been £1-4 billion for each period of flooding, as identified in the Case for Support. The RIBA estimates that future clean-up costs will be in the order of £23 billion in 2050, in the absence of any appropriate measures.

(ii) Damage to infrastructure due to wetting/drying and freeze/thaw cycles. The project will enhance the resilience of infrastructure through barrier systems that will prevent water entry/egress to/from the sub-soil thus preventing the shrink/swell action that causes damage to buildings, roads, railway formations and buried services. Insurance claims due to shrink/swell movements on clay soils have resulted in economic losses in the UK of over £1.6 billion during drought years.

2. It will have social impact through assisting in "greening" the built environment by providing guidelines for civil engineers in adopting vegetation in urban spaces that will enhance the quality of life in UK cities.

3. It will provide contributions to public services and policy, by setting out clear advice on use of climate adaptation technologies that can adopted by town planners and local government.

4. It will provide economic opportunities for geotechnical design consultants and geotechnical contractors as a potentially novel product for climate adaptation that will have an international market.

To ensure impact within the construction industry, the project team will publish a definitive advice document with the Construction Industry Research and Information Association (CIRIA) (similar to CIRIA's SuDS Manual) giving clear design and construction protocols for climate adaptation technologies for urban spaces.