assessing the utility of outline geomorphic sensitivity ... · geomorphology plays an important...
Post on 06-Jun-2020
3 Views
Preview:
TRANSCRIPT
1
ASSESSING THE UTILITY OF GEOMORPHIC SENSITIVITY MAPPING ON
THE ILLAWARRA COAST
Pamela Abuodha1, Christina Baker2, Chris Sharples3, Darren Skene2
and Colin Woodroffe1
1 Geoquest Research Centre, University of Wollongong2 National Coastal Vulnerability Assessment, Geoscience Australia
3 School of Geography and Environmental Studies, University of Tasmania
17th NSW Coastal Conference, Wollongong 4-7 November 2008
Outline
� Aim and objectives
� Components of vulnerability
� National Coastal Vulnerability Assessment� Smartline mapping
� Polygon mapping
� ‘Smartline’ mapping of the Illawarra coast� Landform types
� Sensitivity rankings and maps
� Evaluation of sensitivity
� ConclusionStanwell Park beach
North Wollongong beach Flagstaff Point
Aims and Objectives
� Map landforms that are sensitive to coastal hazards and the
potential impacts of sea-level rise.
� Describe landform types of the Illawarra and derive sensitivity
rankings.
� Evaluate Smartline and polygon mapping.
Exposure Sensitivity
Potential
impact
Adaptive
Capacity
VulnerabilityAllen Consulting Group, 2005
‘Vulnerability’ is a combination of the physical sensitivity, the assets at risk and the
ability of society to cope with these risks (Harvey and Woodroffe, 2007)
Large swell at Flagstaff Point
Seawall at Warilla
Eroded beach dunes at Corrimal beach
What is ‘coastal vulnerability’?
The National Coastal Vulnerability Assessment
� Department of Climate Change - ‘first pass’ assessment of coastal
vulnerability to the impacts of climate change.
� Identify coastal ecosystems and infrastructure most at risk.
� Rely on geomorphic mapping.
� 2 phases,
1. ‘Smartline’ mapping (UTas)
2. Polygon mapping (GA)
Lake Illawarra and Perkins beach
� Available through the OzCoasts website (www.ozcoasts.org.au)
Smartline Maps(University of Tasmania)
� Geomorphic line map of Australia’s
coastal zone using existing geomorphic and geology data.
� Polyline segmented into various
attributes related to the landform type, exposure, geology etc of the coast.
� Identify shores that are potentially
susceptible (sensitive) to physical instability (erosion, slumping etc).
Broad tidally-defined and shore-parallel zones
Backshore(bedrock slope with soil)
Backshore(dune)
2
Coastal geomorphology polygon mapping
� Procure existing digital polygon datasets � State/local government and private consultancies
� Geology, geomorphology and habitat data
� Develop and apply a consistent coastal geomorphology classification scheme.
� Amalgamate datasets and realign with detailed coastline position.
+1:250K Geology
WA Dept. of Industry and Resources
1:100K Geo-habitat Types
Geoscience Australia
Classification Scheme
Level 1
Level 3
Level 2
Level 4
Level 2a
Level 3a
Coastal depositional environment, i.e. alluvial plain, estuarine plain, coastal barrier/backbarrier, shelf, bedrock feature, anthropogenic feature.
Coastal geomorphic feature, i.e. beach, channel, dune, delta… This is the primary field (1:100K – 1:25K).
Coastal geomorphic feature detail, i.e. dune type. Will be mapped if additional information is available (1:25K – 1:10K).
Sediment texture and lithology, i.e. mud/sand/gravel, carbonate, plutonic… (1:250K – 1:100K).
Rock Type, lithology description i.e. basalt, sandstone, conglomerate… Mapped where data is available (1:100K – 1:25K).
Level 5
Biota, i.e. mangrove, salt marsh, coral, seagrass… Mapped where data is available (1:100K – 1:25K).
Substrate type – CONSOLIDATED or UNCONSOLIDATED
Case Study: The Comprehensive Coastal Assessment ToolkitNSW Dept. of Planning
Lake Illawarra to Seven Mile beach
Reclassification – Level 1 Coastal Depositional Environment Reclassification – Level 2 Coastal Geomorphic Feature
3
Reclassification – Level 4 Biota Type Level 5 – identification of consolidated (hard) and unconsolidated (soft)
sediments.
Line vs. Polygon
� Polylines� Store many attributes for a single spatial location (i.e. backshore, near
shore, exposure described in one line segment).
� Allow simple GIS queries.
� Polygons� Map the spatial extent that vulnerable landform units occupy, allows for
modelling of coastal processes.
Lake Illawarra, NSW, geo-habitats Hardy Inlet, WA, intertidal landform type
Illawarra coast� 80 km S. of Sydney
� 167 km long
� Narrow coastal plain
� Wave-dominated
� Over 300,000 people
Stanwell
Park
Seven
Mile
Pacific Ocean
Lake Illawarra
Rocky shore
01
Coarse grained sand
06
Fine –medium grained sand
07
Cliffs & rocky shore
Sediment plains
Dunes & dune ridges
Artificial shoreline
Plains
(0o – 6o)
Gentle slopes
(6o – 20o)
Steep slopes
(>20o)
High cliffs
(> 50 m)
‘Smartline’ segmentation
Intertidal
Backshore
Profile
01 02 03 11
1 2 3 4
Coastline1 432 5 6 7 8
Landform types - intertidal
Coarse grained
06
Rocky shore
01
Fine – grained
07
4
Landform types - backshore
Dunes & dune ridges03
Rocky shore & cliffs 01
Artificial structures 11
Sediment plains
02
Landform types - profile
High cliffed coast 4
Sediment Plains (0o - 6o)1
Moderate slopes ((6o - 20o) 2
Steep slopes (> 20o
3
GIS queries - sandy sensitivity
!!
!!
!!!
!!
!!!
!!
±
200 m
Intertidal 07 (fine sand)Backshore 03 (dunes)
Profile 1 (low plains)
Intertidal 07 (fine sand)Backshore 11 (artificial)
Profile 1 (low plains)
Intertidal 07 (fine sand)Backshore 01 (bedrock)
Profile 1 (low plains)
07 + 03 = 23 Sandy shores backed by dunes
07 + 11 = 27
Sandy shores backed by artificial
structures
07 + 01 = 25
Sandy shores backed by bedrock
GIS queries - sandy sensitivity
Intertidal = 07Fine sand
Backshore = 01Bedrock
07 + 01 = 25
Backshore = 02
Profile = 1
Intertidal = 07
07 + 02 + 1 = 20
Backshore = 11Artificial
Intertidal = 07Fine sand
07 + 11 = 27
Intertidal = 07Fine sand
Backshore = 03Dunes
07 + 03 = 23
Illawarra sandy sensitivity
Intertidal
!
!!!! !
!!! !! !
!!
!
!! !!!
!!! !!!
! !!!!!!!
!
! !
! !
! !
!! !
!! !
!! !! !
!
!!
!
!
! !!!
!
! !
!!
!!
!! !! ! !
!
!!!!! !!! !!
!
!
!
! !
!
!
! ! !!
! !!
! !
!!!! !!
!
!! !!!!
! !
! !
!
!!!
!!
!
!
!
!
!
!!
!
!
!
!
!!
!
!
!
!! !
!
!
!
!!
!
!
!
!
!!
!
!
!
!
!
!!!
!
!
! !
±
5 km
! ! ! ! 01
06
07
01
06
07
Backshore
!!!!!
!!!!!!!! !
!!! !!
!
!
!!
! !!!!!!! !! !!!
!! !!!
!! !!!! !!!!!
!!! !!!!!!
!!! !!
!
! !
! !
! ! !
!! !!!
!! !
!!
!! ! !! ! !
! !
!!!! !!!
!
! !
!!
!!
!! !! ! !
! !!!!! !!!! !!
!!
!
!
! !
!
!
! ! !
! !!
! !!!
!!!! !!
!
!! !!!!
! !
! !
!
!
!! !! !
!
!
!
!
!
!!
!
!
!
!
!!
!!
!
!! !
!
!
!
!!
!
!
!
!!!
!
!
!
!
!
!
!!!
!
!
! !
!
±
5 km
! ! ! ! 01
02
03
11
+
01
02
03
11
Profile
+
!
!!!!!!!! !
!!! !
!
!
!
!!
! !!!!!!!!! !!!
!!
!!!
!! !!!!! !! !!!!
!!!! !!!! !!!! !!!
!!
! !
! !!
!
!!! !
! !
!
! !!!!
! !!! !!
!
! !
!
!! !!
!!!
!
!
!
!
!
!
!
!
!
!
!
! !
!
!
±
5 km
1
! ! ! 2
3
1
2
3
Sensitivity
!!!
!!!! !!!!
!!!!!!
!
!
!
!!
!!
!
!
±
5 km
00
20
23
25
! ! ! ! 27
30
37
40
=
00
20
23
25
27
30
37
40
45.5
0.2
54.3
0.0 10.0 20.0 30.0 40.0 50.0 60.0
Rocky shore (01)
Coarse-grained sandy
shore (06)
Fine-medium grained
sandy shore (07)
Inte
rtid
al la
nd
form
typ
es
Percentage of shoreline
47.1
23.1
18.3
11.5
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0
Rocky shore or cliffs (01)
Sediment plains (02)
Dunes and dune ridges
(03)
Artificial structures (11)
Backsh
ore
lan
dfo
rm t
yp
es
Percentage of shoreline
5
47.3
17.8
34.9
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0
Exposed (1)
Semi-exposed (2)
Sheltered (3)
Sh
ore
lin
e s
eg
men
t exp
osu
re
Percentage of shoreline
70.8
22.5
6.7
0.0
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0
Low plains (1)
Gentle to moderate
slopes (2)
Steep slopes (3)
High cliffs (4)
Backsh
ore
in
lan
d s
lop
e
Percentage of shoreline
Sandy sensitivity for the Illawarra
37.4
7.6
18.3
5.5
4.4
15.4
3.3
8.1
0 5 10 15 20 25 30 35 40
Not a sandy shore (00)
Open sandy shores backed by plains (20)
Open sandy shore backed by dunes (23)
Open sandy shore backed by bedrock (25)
Open sandy shore backed by artificial
structures (27)
Re-entrant sandy shore backed by plains (30)
Re-entrant sandy shore backed by structures
(37)
Sheltered re-entrant but not a sandy shore
(40)
Sa
nd
y s
en
sit
ivit
y
Percentage of shoreline
Low
Moderate
High
Conclusions
� Geomorphology plays an important role in the identification of coastal areas that are vulnerable to the potential impacts of sea-level rise.
� Coastal geomorphology maps are currently being developed for Australia and these will provide fundamental data layers for assessing the impacts of sea-level rise.
� Illawarra coast:
- high sensitivity 25.9 %
- moderate sensitivity 15.4%
- low sensitivity 21.3 %
- non-sandy shores 37.4 %
� Future study:
Investigate historic rates of shoreline movement
Bellambi/Woonona beach
Questions?
top related