IAP2-23-134

Compound Floods: Fluvial and Surface Water Flood Nature based Solutions

Flooding, and its management, cost the UK £2.2billion per year. Many locations across the UK now experience compound flood risks, whereby risks associated with fluvial (river) and surface water (pluvial) flooding interact. Under current climate change and economic pressures, flood management policy is shifting from entirely flood defences to broader management strategies which involve holistic, multi-benefit and integrated approaches. This includes “Natural Flood Management” and “Nature based Solutions” (NbS) which aim to restore the natural functioning of catchments and cities to store water and slow the flow. Catchment wide solutions often include tree planting, setting aside upstream agricultural land and soil management. In cities, sustainable urban drainage systems (SuDS) can be used to manage surface water drainage and include rain gardens, green roofs and swales.

This PhD will focus on the flood risk problem in Musselburgh, near Edinburgh, and the wider River Esk catchment. Musselburgh has been identified by SEPA as a “Potentially Vulnerable Area” under the Flood Risk Management Act Scotland (2009) meaning that East Lothian Council have to act to reduce flood risk within the town. Floods have occurred historically in 1927, 1948, 1966, 1990 and 2000. Currently 900 properties are at flood risk from the 1 in 200-year return period flood event. In 2016, the council commissioned the Musselburgh Flood Protection Scheme (MFPS) to manage flood risk. The town also experiences surface water flooding from sub-surface sewer network capacity being exceeded, especially during high river flows

However, despite gaining popularity with policy makers and flood action groups, a lack of evidence on the effectiveness of Nature based Solutions and advice regarding the implementation of these innovative approaches are limiting its uptake.

This project will look at the interactions between the different sources of flooding (river, surface water, sewer flooding) and determine how each are managed. Particular questions of interest include:
– How do floods generated upstream in catchments impact on surface water floods in urban areas downstream?
– Are the same type of NbS beneficial for managing both fluvial and surface water flooding?
– How can NbS in the wider catchment be combined with NbS in the urban areas themselves to mitigate both types of floods?
– How do traditional engineering approaches to fluvial flood management e.g. walls, embankments interact with surface water flooding management interventions?

This project will work closely with the Musselburgh Flood Protection Scheme and other interested catchment stakeholders to develop practical, applied understanding of the above questions.

This project will utilise a mixed methods approach, combining field monitoring, numerical modelling and stakeholder engagement.

Field trials will seek to form a process-based understanding of how individual NbS features function, for example using a wide range of soil property tests to study role of agricultural management/urban SuDS in flood mitigation and quantify scale dependency and similarity of processes between different types of NbS.

Numerical modelling, hydrological and hydraulic models, will be used to upscale the results to the larger catchment scale and also to compare and test different “What if” scenarios.

Finally, you will be able to engage with the stakeholders in this real time flood management project, the Musselburgh Flood Protection Scheme, and consult with a large number of environmental catchment manager stakeholders to understand the factors which govern what type of NFM features are popular and what measures could be put in place to overcome barriers of implementation. Potential methods of engagement could include, but are not limited to, questionnaires and focus groups.

Year 1

General research skills training (e.g. literature reviewing, project management, working with stakeholders). Undertake a comprehensive literature review and develop detailed project objectives, particularly around which NBS interventions will be focussed upon, and design monitoring experiments to test their effectiveness and assess the multiple benefits.

Year 2

Continue field monitoring of NBS interventions and develop models for larger scale assessment of the multiple benefits and their effectiveness.

Year 3

Finalise data collection and analysis. Work closely with stakeholders to ensure key messages are translated into practice and policy.

Year 3.5

Thesis Writing and journal publications

In addition to the core training provided by IAPETUS2, you will undertake specific training on numerical modelling through dedicated courses arranged by HR Wallingford and the Environment Agency. You will also attend a 5 day Annual Catchment Science Summer School, led by internationally leading hydrologists. Further training opportunities will be accessed through the British Hydrological Society. The student will get the opportunity to present their research at a range of national and international conferences, to build communication and networking skills. You will be a member of the Nature based Solutions research group at Heriot Watt, which run a series of seminars and training workshops.