How can coastal management strategies be harmful in other places along the coast?

This is the process of downdrift, which is when the dynamic equilibrium of the coastal system is upset by manmade process, such as the installation of 'groynes'. Groynes are features which stick out past the coastline to prevent erosion by LONGSHORE DRIFT, which happens on 'drift aligned coastlines' (which are at an angle to the prevailing wind), as the current pulls the sand from the shore back directly and brings it forward again at an angle, like a zigzag motion. Groynes therefore trap the sand within each segment of beach, preventing erosion via longshore drift. However, this has knock-on effects further down the coastline as the sediment which is used to form the beach has not entered into the system and therefore the beach may lose material.