Supervisors:
Dr Justin Dix (UoS), Dr Mark Vardy (NOC), Professor Richard Whitehouse (HR Wallingford), Dr John Harris (HR Wallingford), Dr Chris Roman (UoRI), Peter Hogarth (Kongsberg Maritime)
Case/industry partner:
Kongsberg Maritime, HR Wallingford
The last decade has seen a proliferation in the construction of a wide range of engineering structures offshore (e.g. windfarms and other marine renewable structures; offshore components of nuclear power stations; and a wide range of cables and pipelines). Placing any object within a bi-directional [tides], oscillatory [waves] and combined [tides and waves] flow regime can lead to flow acceleration and the extensive erosion (scour) and re-deposition of material associated with such objects. Scour can result in the exposure of buried infrastructure, significantly reducing structure stability and affecting structure performance. The majority of research and monitoring to date has focused on measuring maximum scour depth and at time intervals of many months or even years after installation. However, recent collation of disparate extant datasets, measurements from bridge piers in rivers and physical modelling suggests that the key period for scour development can be in the first few days after installation. This project aims to undertake the first continuous survey to capture the initial phase of scour evolution around an offshore structure. In order to get continuous survey data and as extensive coverage around a structure data acquisition will be undertaken from a commercially available AUV.
This project intends to use the Kongsberg Maritime Munin AUV, with a payload to include EM2040 multibeam swath bathymetry system, HISAS 2040 interferometric synthetic aperture sonar or an Edge Tech dual frequency side scan sonar and potentially and Edge Tech swept frequency sub-bottom profiler. This AUV has an endurance capability of between 12-24 hours and can be easily recovered, batteries replaced, data extracted and re-deployed from small vessels of opportunity to allow almost continuous running. The aim of this project will be to deploy the system within 1-2 hours of a structure being emplaced on the seabed and to run continuously for a maximum of 10 days after the installation or to the point at which scour has reached a quasi-equilibrium state. Data will be processed, integrated and analysed using a range of software (e.g. CARIS, ARCGIS, CODA, Petrel). We shall also be able to include both geophysical and hydrodynamic data from ambient conditions both prior to and post-installation as collected as part of conventional boat based surveys for monitoring purposes. We shall also utilise SLAM (Simultaneous Localisation and Mapping) algorithms developed by URI to enhance positional accuracy and hence fidelity of scour growth with time.
The NEXUSS CDT provides state-of-the-art, highly experiential training in the application and development of cutting-edge Smart and Autonomous Observing Systems for the environmental sciences, alongside comprehensive personal and professional development. There will be extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial / government / policy partners. The student will be registered at University of Southampton, and hosted at Ocean and Earth Science. Specific training will include: deployment and retrieval of the AUV (Kongsberg Maritime); processing of all geophysical and hydrodynamic datasets (OES – using established modules); scour processes (HR Wallingford – attending established courses). There will also be the opportunity for the student to spend a short period at the University of Rhode Island to work on applying the SLAM algorithms to the data.
Background Reading:
Harris, J. M., R. J. S. Whitehouse, and T. Benson (2010), The time evolution of scour around offshore structures, Proceedings of the Institution of Civil Engineers, Marine Engineering,163 (MA1), 3–17, doi:10.1680/maen.2010.163.
Whitehouse, R. J. S., J. M. Harris, J. Sutherland, and J. Rees (2011a), The nature of scour development and scour protection at offshore windfarm foundations., Marine Pollution Bulletin, 62 (1), 73–88, doi:10.1016/j.marpolbul.2010.09.007.
To apply for this project, use the: apply for a NEXUSS CDT studentship