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SWOT-UK: The UK contribution to validating SWOT in the Bristol Channel and River Severn, with application to coastal and river management.

Lead Research Organisation: University of Bristol
Department Name: Geographical Sciences

Abstract

The Surface Water and Ocean Topography (SWOT) mission will provide for the first time from space two-dimensional high-resolution maps of surface water levels globally over ocean and inland waters. If SWOT meets its performance targets, it will represent a major milestone in our abiity to observe, study and understand the nature and evolution of the Earth's marine and land surface water systems, globally. The UK Space Agency invested in SWOT jointly with the US NASA, French CNES and Canadian Space Agency to enable the implementation and launch of this mission. The SWOT-UK project proposes a comprehensive programme of campaigns and multidisciplinary research centred on the Bristol Channel and River Severn region as the UK contribution to the international SWOT Science Team validation efforts. In accordance with the requirements of the NERC/UKSA SWOT CalVal call, SWOT-UK takes an open and inclusive approach, putting special emphasis on disseminating value-added SWOT validation datasets and engaging with the wider UK science and stakeholder communities to raise awareness of the SWOT capabilities.
 
Description Conventional radar altimeters struggle within 5-10 km of shorelines due to land-water interference, large footprints, and wide inter-track spacing. While SAR-mode altimetry and waveform retracking improve near-shore (1-5 km) coverage, residual errors, and inter-track gaps limit fine-scale coastal applications. Surface Water and Ocean Topography (SWOT)'s Ka-band radar interferometry promises to overcome these limitations, delivering wide-swath water surface elevation (WSE) monitoring in complex coastal systems. We validated SWOT during its March-July 2023 Calibration/Validation (Cal/Val) phase in the macro-tidal Bristol Channel using ADCP-mounted pressure sensors, tide gauges, and ~446 million airborne LiDAR points under varying tidal conditions. Spatial aggregation with quality control produces accurate WSE estimates despite high pixel-level variability, demonstrating SWOT's capability to capture coastal hydrodynamics and extend reliable WSE observations into challenging coastal environments.
Exploitation Route The research undertaken proves that the SWOT satellite can be used for water elevation monitoring in dynamic coastal zones.
Sectors Aerospace

Defence and Marine

Agriculture

Food and Drink

Communities and Social Services/Policy

Construction

Energy

Environment

Financial Services

and Management Consultancy

Leisure Activities

including Sports

Recreation and Tourism

Culture

Heritage

Museums and Collections

Transport

URL https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2025GL116590
 
Description Collaboration with Clevedon Pier & Heritage Trust 
Organisation Clevedon Pier & Heritage Trust
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution We are using Clevedon pier to install monitoring equipment for our project and will also be developing public outreach activities with them
Collaborator Contribution Provided access to pier for installing instruments.
Impact None yet
Start Year 2021