Groynes are cross-shore structures designed to reduce longshore transport on open beaches or to deflect nearshore currents within an estuary. On an open beach they are normally built as a series to influence a long section of shoreline that has been nourished or is managed by recycling. In an estuary they may be single structures.
Riverine floods or slow rise floods are induced by large scale precipitation or snow melt. In contrast to flash floods, slow rise floods or riverine floods are characterised by relatively slow onset (up to several days), a less severe increase of discharge, increased but still moderate flow velocities and moderate sediment and debris transport.