INSHORE - Integration of optical and acoustic remote sensing data over the backshore-foreshore-nearshore continuum, a case study in Oostende

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Context and objectives

In the view of the ongoing sea-level rise, an effective management of the Belgian coastline becomes increasingly important. In this, a realistic estimation of the coastal sediment budget is crucial and requires data from the dune foot up to the seabed. Studies are mostly restricted to the beach and only sporadically the nearshore zone is taken into account. However, coastal processes act over the continuum of the dunes to the near- and offshore (hereafter called the inshore area) and it is often the morpho-sedimentary state and dynamics of the latter that will determine how well beach sections recover from erosive events or if sufficient sediment is available to cope with sea-level rise.

The INSHORE project aims at integrating optical and acoustic remote sensing data in view of studying morpho-sedimentary processes over the nearshore-shore continuum. This corresponds to an area that comprises the dry beach (backshore), the intertidal beach (foreshore), the nearshore (lower shoreface) and the first nearshore channel. This spatial continuum will be called inshore.

he objective of this project is to develop and test a methodology to produce spatially integrated sedimentological and morphological maps over the inshore continuum. The purpose is that this methodology can be applied in future studies; as such its set-up is ideally based on a dataset that is sufficiently detailed and diverse in terms of its sedimentology and morphology.

Project outcome

  1. Based on different airborne LiDAR datasets obtained in the period 2004 – 2009 relevant height difference maps could be constructed in order to study the morphological evolution of the dry beach area. This data was completed with bathymetric data of the nearshore to get a complete coverage of the inshore area. Difference maps of the complete inshore area could be produced showing the morphological evolution over the past years (2004 – 2009). The results are classified maps and vector files.
  2. The airborne hyperspectral data, in combination with in the field collected ground truth data, was used to classify the dry beach area in: (a) 16 highly detailed classes with an average accuracy of 97 % and a kappa of 0.96. In order to obtain a workable map and for comparison with historical data, the detailed classes were merged to eight significant classes leading to an average accuracy of 98 % and a kappa of 0.97.
  3. Both, multibeam backscatter and sidescan sonar data were used to produce a sedimentary surface facies map of the nearshore area. Because no automatic classification method is available yet, manual screening of the data was done in order to produce twelve sedimentary classes.
  4. Finally, the airborne and seaborne derived maps were combined to construct an integrated sedimentological and morphological map of the inshore continuum which were used subsequently to interpret and formulate statements about the sediment dynamics of area.