Hero photograph
Moeraki township, New Zealand
Photo by Eli Duke

Land movement

Lesley Brook —

Coastal land stability issues were the subject of research projects by several of our Civil Engineering students.

For many years now Haven Street in Moeraki township has suffered from land slips after heavy rain events. Scott Rhodes investigated the causes and possible solutions in his final year research project, consulting with the community, iwi and the local authority. Unfortunately slowing land movement to keep the road open is likely to be very expensive. 

Sarah Maybin looked at coastal erosion at St Clair Beach, Dunedin. A decline in sediment inputs from rivers to the south may be a factor. Sand sampling indicated that mechanical weathering occurs during long shore transport of sediment northwards. Sarah suggests that a breakwater extending from an existing rock wall would help with beach sand retention.

A decommissioned landfill lies under Kettle Park in Dunedin, adjacent to Middle Beach. Beach erosion means there is a risk of breach of the sand dune and exposure of hazardous waste. Devon Quinn designed a sloped seawall revetment to reduce this risk.

Coastal erosion has also been a problem at Ringaringa Beach in Paterson Inlet, Rakiura. Loss of sand from the beach means the cliff is eroding, endangering houses and a community golf course. Cameron Sinclair recommended and designed a rock revetment to reduce risk. A groyne or plantings could help slow migration of sand southwards.