Beach nourishment to mitigate the impact of sea level rise in Southeast Australia

Beach nourishment to mitigate the impact of sea level rise in Southeast Australia

Langedijk, J.M.P.A.

Stive, M.J.F. (mentor)
Cowell, P.J. (mentor)
van de Graaff, J. (mentor)
Enserink, B. (mentor)

University of Sydney

Civil Engineering and Geosciences

2008-11-21

The rise of sea level (18 to 91 cm in South Australia by the end of the 21st century) will result in beach erosion and, hence, poses a significant risk to the beaches of southeast Australia. This risk can be mitigated by means of beach nourishment. The costs of applying beach nourishment to the coast of southeast Australia in the 21st century have been estimated in the present study. The uncertainty associated with sea level rise and its impact on the coast has been managed by adopting a probabilistic approach. The expected offshore sand losses due to sea level rise have been estimated with the raising the profile method, a derivative of the Bruun Rule, and are between 2.8 and 6.2 billion m3, where the actual value depends on the selected risk level (between 1 and 50%). The offshore sand resources in southeast Australia contain enough good quality sand to replenish these sand losses. Because the economic viability of applying beach nourishment depends strongly on the degree of beach development, it has been assumed that only the presently developed beaches (20% of the coastline), in due time, the future developed beaches (up to 60%) will be nourished. The beach nourishment costs have been estimated by multiplying the required amounts of sand with the sand costs, which are the lowest in case of using offshore sand resources. In that case, the costs of nourishing the presently developed beaches are between 2.6 and 6.3 billion Australian dollars and the costs of nourishing both the presently and the future developed beaches are between 7.3 and 17.4 billion Australian dollars. However, offshore sand extraction is currently prohibited in the state New South Wales and in case the beaches are nourished with onshore sand, the costs will be about seven times higher. The results of the present study can be used to develop an economically optimum beach nourishment programme.

beach nourishment
Southeast Australia
sea level rise
Bruun rule
probabilistic approach

http://resolver.tudelft.nl/uuid:002370b6-d8cf-47dc-9269-78a54faa3b8f

TU Delft, Civil Engineering and Geosciences, Hydraulic Engineering

Student theses

master thesis

(c) 2008 Langedijk, J.M.P.A.