Coastal Sand Dune Degradation
and Rehabilitation
James Ruediger
Coastal Sand Dunes, Little Dip National Park, South Australia
Why are Coastal Dunes so important?
• Dunes are critical to
the health of a beach
system.
• Storage of sand to
replace beach sand
lost during storm
events
• Essential havens for
wildlife and plant
species.
Healthy dune vegetation, South Port beach.
Case Study: Adelaide’s beach and dune
system.
• Every coastal system is
different.
• Adelaide has a rather
unique system with
strong coastal currents
and very limited input
of material.
• Large levels of
development on coast
has affected dune
systems significantly
Courtesy of SA Dept. of Planning
Case Study Site: South Port Beach
• One of the best
examples of a healthy
beach system in
Adelaide.
• Mouth of Onkaparinga
River
• Extensive upkeep by
volunteers and
environment groups
• Restricted from
development to
preserve environment.
South Port beach showing dunes and river
Case Study Site: Hallett Cove
• Unusual beach system, all
material for small dune
system is from erosion of
cliffs above.
• Beach system heavily
influenced by
development, first shacks,
then housing, then
Conservation park reserve.
• Site of recent
rehabilitation work by
National Parks and
community groups
Hallett Cove Beach
Case Study Site: Glenelg North Beach
• One of the most developed
beach areas on the Adelaide
coastline.
• Dunes levelled and sealed
with housing and roads
• Main river, The Patawalonga,
heavily flow controlled.
• Beach non existent at high
tide, and storms often wash
onto roadways.
• Riprap walls installed to
protect housing cause even
greater scouring of beaches
by waves.
Aerial view of Glenelg North beach, courtesy City of Holdfast Bay.
So what's so special about Adelaide's
Dune system?
• Adelaide, being built on a gulf, experiences
strong South-North coastal currents
• Very limited material input into system, Three
main rivers, Onkaparinga, Sturt/Patawalonga,
Torrens, All dammed.
• Sand migration in current scours southern
beaches and deposits on northern beaches
• High level of urban development onto dune
fields and beach fronts.
And the result of this?
• Most of Adelaide's beaches
are severely degraded.
• Many beaches vanish
completely at high tide.
• Loss of breeding sites for
fauna and important flora.
• Storm events can cause
waves to overtop coastal
embankments and damage
houses and roads.
• Costs to society- Sand
cartage, Dredging,
replenishment, Aesthetics,
Infrastructure repairs.
Henley Beach, 1953 showing storm damage. Courtesy of DENR
Rehabilitation?
• Whilst it is impossible to easily restore a lot of
Adelaide's dune systems, short of demolishing
very expensive houses, it is possible to restore
and maintain those areas that remain.
• Several key areas, as part of the parks and
reserves system, such as Aldinga Beach, South
Port, Hallett Cove and Tennyson are being
managed and rehabilitated.
Where to start?
• DENR recently undertook
works at Hallett cove to
protect the remnant dune
system.
• Boardwalks to limit erosion.
• Fencing to exclude people
from sensitive areas
• Revegetation
• Sand matting to limit
erosion.
• Community Education
• Weed species removal
• Only the beginning- much
more work still needed.
Fencing, Reveg area and boardwalks at Hallett Cove
Hallett Cove- Lots to be done…
New vegetation growing through sand matting
Sand grass slowly rehabilitating dune/beach interface
Getting There….
• South Port beach is an
example of a much
better maintained
ecosystem.
• Strong vegetation
communities
• Active community
groups and council
support for the area.
• Sustainable balance of
conservation and
public utilisation.
Healthy dune-beach interface, South Port Beach
Dunes. Using them the RIGHT way.
Area of
erosion
controlled
with fencing
and
replanting
Storm
damage
repaired with
compostable
seagrass
sand bags
Boardwalks keep foot traffic off dunes,
limiting erosion and vegetation destruction
Conclusions
• No “quick fix” - much of the damage has
already been done and is essentially
irreversible
• Critical to maintain and rehabilitate the areas
we have left.
• No “One solution fits all” - coasts in Adelaide
differ to coasts in other capital cities and
require different management methods.
References
• Department of Environment and Natural
resources: Coastal Management Branch
• Coast care SA
• City of Holdfast Bay
• Adelaide and Mount Lofty Natural Resource
Management Board.
• All photographs by author unless otherwise
noted.