Co-designing Opportunities and Modelling Performance of Catchment Scale Natural Flood Risk Management: Stour Valley, Warwickshire-Avon, UK

  • Tom Lavers

Student thesis: Doctoral ThesisDoctor of Philosophy

Abstract

Flood Risk Management (FRM) in the UK has undergone a paradigm shift in response to recent catastrophic flood events, particularly the June/July 2007 summer floods and the winter floods of 2015/2016 that affected much of Northern Britain, Northern Ireland and parts of Wales. Traditional engineered FRM techniques, such as river walls and levees, have historically been designed to increase conveyance in the water network, moving storm-flow downstream from the community at risk.
However, more recently a holistic catchment systems approach targeting FRM activities in the farmed uplands, known as Natural Flood Risk Management (NFRM), has gained increasing prevalence in policy and practice. NFRM constitutes a wide variety of techniques that aim to alter the biophysical characteristics of catchment surfaces for a reduction in conveyance, attenuating the downstream peak through the manipulation of upstream storm-flows. Whilst advocated, there are large gaps in research and practice such as how receptive farmers are to altering their land management practices to slow, store, infiltrate and disconnect flood flows. These critical stakeholders are also recognised to provide valuable local knowledge and place-based thinking that can better inform where best to apply NFRM techniques. There is also a critical need for a better understanding of NFRM performance to provide much needed empirical evidence. This lack of quantification, especially at the large catchment scale,
prevents such an approach becoming more widely adopted.

In this study a new, integrated Participatory GIS (PGIS) mapping framework has been devised and tested with 38 farmers across the study site in order to co-design NFRM, applying active engagement and local flood risk management (LFRM) communication methods. The digitised PGIS-NFRM scenario
was tested against a distributed rainfall-runoff model to demonstrate the performance of the techniques to multiple hydrological scales and rainfall events. The research found farmers were variably receptive to having NFRM techniques applied to their holdings. Furthermore, there was considerable variation in the number and types of techniques identified, which was highly dependent on cadastral land use. The performance of the PGIS-NFRM techniques was also found to be variable
based on event magnitude, antecedent conditions, sub-catchment timings of peaks and types of techniques applied. NFRM mainly demonstrated a reduction in flooding from smaller events,
especially at small hydrological scales (<10km2). However, it did not demonstrate significant flood risk benefits for larger events, especially at scales >100km2. The study is the first of its kind to show how local knowledge can be incorporated into NFRM, and wider LFRM, decision-making. As a result itgenerates a transferrable framework for relevant agencies, river management authorities and catchment stakeholders to adopt when identifying NFRM opportunities and tests their performance across multiple hydrological scales and different rainfall events.
Date of Award2021
Original languageEnglish
Awarding Institution
  • Coventry University
SupervisorSM Charlesworth (Supervisor)

Cite this

'