Making space for coastal change in cities: Which reclaimed land can we let go? (UrbanCoastAdapt)
The most recent IPPC report (IPCC, 2021) clearly shows sea levels will continue to rise until 2300 and (landward) retreat is one of the six recommended responses to maintain community resilience in the face of sea level rise. Around the UK, erosion risks due to climate change are accelerating and in many urban areas coastal and estuarine engineering structures are coming to the end of their design life. The land currently protected by these structures is often comprised of artificial made ground – land that was reclaimed by extending into the sea, which is often post-industrial, currently derelict or has light industrial use which is often identified by planners as suitable land for ‘regeneration’. This combination of low value land use and unsuitable defences gives society a choice– protect this low-lying land at increased risk and cost with rising sea levels – or return land to the sea, in order to improve the long-term resilience of our coastal cities and towns? If we want to consider the latter option, then we urgently need more data on the composition, erosivity and rates of sediment transport of this often highly heterogeneous ‘made ground’. These data are required to provide an evidence base to better underpin urban coastal climate change adaptation options and restoring of the land-sea natural boundary using nature-based solutions.
Without data on the nature, processes and change of former made or reclaimed urban ground, it is difficult to assess risk, to determine if it is feasible for this made ground to ‘retreat’ by allowing erosion and coastal realignment to a more natural position. This retreat option has the potential to reduce the requirement for developing or maintaining expensive hard coastal defenses and to allow us to live more sustainably with a dynamic coast. This project will address this key knowledge gap, by carrying out pioneering research in urban geomorphology and climate change risk assessment that can directly feed into existing practitioner tools & datasets.
The project’s specific objectives are to:
1) Characterise made ground using secondary data from a range of sources (e.g. local authorities, British Geological Survey) and using GIS, map the distribution of made ground along the UK coast subject to natural erosion and associated future climate change risks (e.g. using existing coastal erosion risk data).
2) Undertake field surveys and laboratory analyses to assess the geomorphological and sedimentological characteristics of artificial made ground – on land and also on reclaimed land and the coastal sedimentary systems fronting them. This detailed scientific work, using a range of geospatial (e.g. LIDAR, SfM) and laboratory testing methods (e.g. ICP-OES/MS to determine ecotoxic metal concentrations), to determine for selected UK sites: how toxic is this made ground, what is its sediment composition and volume?
3) Investigate and model the morphodynamic processes and sediment transport pathways controlling the integration of made ground materials within coastal sedimentary systems to help answer how fast may this heterogenous made ground erode and mix into the more natural coastal sediment system?
4) Develop an outline risk assessment framework to aid identification of reclaimed land sites with artificial sediments suitable (i.e. benign enough) to retreat and re-enter the coastal system.
1) quantitative data to underpin coastal change risk assessments and climate change adaptation planning to support government agencies and local authorities.
2) Methodology for identifying and assessing the suitability of made ground for urban managed realignments.
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Urban mixed beach in Edinburgh,Urban reclaimed land,Advanced drone technology