example at the seaward side the morphology of the sea bed is an important
factor. The line up to where the sediment processes are significant may
act as the coastal zone boundary. At the landward side, the end of dune
formation may act as a boundary. However, situations exist where (parts
of) river basins must be included in the 'coastal zone' because of the
influence of their discharge and transported matter on the problems considered.
In such cases, the extent of the considered area enlarges considerable
and may cross international boundaries.