Natural flood management (NFM) is an emerging form of land management which works with natural processes to reduce flood risk. The evidence basis for NFM schemes is immature but is growing, with wetland unimproved grassland being a particularly
understudied ecosystem in need of evidence-based research. The research presented in this thesis aimed to assess the extent to which unimproved grassland, a formerly extensive habitat that has been greatly reduced by intensive agriculture, could provide NFM benefits. This study specifically focused on unimproved grassland in southwest England known as Culm grassland; comprising of purple moor grass (Molinia caerulea) and rush pasture (Juncus effusus). Improved grassland (Lolium perenne) fields were used as a comparison/control as the grassland species which now dominates North-west European agricultural landscapes.

The study was divided into four objectives spanning a range of spatial scales to gain a multi-scale understanding of unimproved grassland hydrology. Objective 1 focused upon soil and water table properties using soil sampling and water table monitoring via dipwells. Results showed that M. caerulea and J. effusus dominated fields had on average significantly less compacted soil and slowly released water after rainfall events, compared to the more compacted and flashier L. perenne dominated sites. The research was continued in Objective
2 which used a rainfall simulator to mimic a 40 mm/hr rainfall event over plots of the three grassland types. Results showed a significant relationship between soil compaction and when saturation was reached, but volume of runoff was likely influenced by vegetation density within each plot, as no clear relationship between grassland type and overland flow was found. Objective 3 quantified surface flow pathway length in a field of M. caerulea and L. perenne using an unpiloted aerial vehicle and structure from motion photogrammetry to produce a detailed surface model through which surface flow pathways could be measured. The M. caerulea field had on average 1.4 times greater flow pathway length than the L. perenne control field and a rougher round/vegetation surface which could delay and store surface water. All three field experiments fed into Objective 4: sub-catchment rainfall-runoff response modelling of the Upper Tamar. Scenarios of 0, 10, 20 and 30% unimproved grassland restoration were modelled to assess potential impacts on within river flood hydrographs. Results showed peak flow and peak volume were reduced with increasing unimproved grassland extent. The four objectives of this study showed that unimproved grassland restoration has a place in the NFM toolkit, and that unimproved grassland can deliver other environmental benefits such as greater carbon storage and a diverse habitat for wildlife.

Natural flood management (NFM), or working with natural processes, is a growing flood risk management method in the UK, Europe and worldwide. However, unlike the current dominant technical flood management, it lacks an established evidence base of flood risk parameters. This lack of evidence base can limit the uptake of NFM as a flood management method. This paper critically evaluates examples of NFM and wider relevant literature in order to identify NFM knowledge gaps and suggest how to overcome these. The UK is used as a microcosm of different environments for diverse examples. The sections include: land cover, land management, landscape interactions and trade-offs, evaluating the wider benefits of NFM and, finally, scaling from plot to catchment. This concludes in a suggested framework for a new approach to NFM research, which encompasses spatial scales, interactions and trade-offs of NFM and consistency of reporting results. Widening the NFM empirical evidence base should be seen as an opportunity for a new approach to flood research through exploring new habitats and new flood resilience methods.

Footpaths are a prominent consequence of natural area tourism and reflect damage caused to valuable, sensitive habitats by people pressure. Degradation impacts on vegetation, wildlife, on and off-site soil movement and loss, creation of additional informal off-path footpaths (desire lines), and visual destruction of landscapes. Impacts need to be measured and monitored on a large temporal and spatial scale to aid in land management to maintain access and preserve natural environments. This study combined remote sensing (Light Detection and Ranging [LiDAR] and aerial photography) with on-site measurement of footpaths within a sensitive heathland habitat (Land's End, Cornwall, UK). Soil loss, slope angle change, vegetation damage and a hydrology model were combined to comprehensively study the site. Results showed 0.09 m mean soil loss over five years, footpath widening, increasing grass cover into heathland, and water channelling on the footpaths exacerbating erosion. The environments surrounding the footpaths were affected with visitors walking off path, requiring further management and monitoring. Multiple remote sensing techniques were highly successful in comprehensively assessing the area, particularly the hydrology model, demonstrating the potential of providing a valuable objective and quantitative monitoring and management tool.