Hard engineering = expensive, manmade structures, faster results but short term.
Soft engineering = cheaper, natural processes, slower results but long term.
Hard Engineering:
http://www.youtube.com/watch?v=HiNGGwRfdMU
You can see that hard engineering is very expensive and is often used to protect properties and other manmade structures. This is often used as immediate prevention that would otherwise cause extensive and expensive damage.
This is a simple flash on groyne, groynes are used to prevent erosion by longshore drift.
http://www.bbc.co.uk/schools/riversandcoasts/coasts/change_coast/pg_18_flash.shtml
