The survey brief was to provide seabed levels within all areas where the seabed level was lower than -1 metre below OD(N).  A dense grid of seabed levels were required to complement an aerial lidar survey to give complete coverage of the estuary.  The survey presented numerous challenges to overcome.  The areas to be surveyed were uncharted and required careful navigation over the 8000 hectare area of Site of Specific Scientific Interest (SSSI) where the sand banks migrate regularly.  Tidal windows were limited to a maximum of 4 hours on the top of a spring tide.
 

To provide the seabed levels required, the locations of the channels first had to be identified.  As no information was available from the recent lidar survey, a previous survey was utilised to outline the approximate areas of investigation.  With the use of RTK GPS aboard a shallow drafted survey vessel, real time seabed levels could be calculated and the survey area extended to meet the specified seabed level.
 

Project date: Summer 2006 – 2008