Aim and objectives Components of vulnerability National Coastal Vulnerability Assessment 2

Transcription

1 ASSESSING THE UTILITY OF GEOMORPHIC SENSITIVITY MAPPING ON THE ILLAWARRA COAST Pamela Abuodha, Christina Baker, Chris Sharples, Darren Skene and Colin Woodroffe Geoquest Research Centre, University of Wollongong National Coastal Vulnerability Assessment, Geoscience Australia School of Geography and Environmental Studies, University of Tasmania Outline Aim and objectives Components of vulnerability National Coastal Vulnerability Assessment 7th NSW Coastal Conference, Wollongong -7 November 008 Smartline mapping Polygon mapping Smartline mapping of the Illawarra coast Landform types Sensitivity rankings and maps Evaluation of sensitivity Conclusion Stanwell Park beach Aims and Objectives What is coastal vulnerability? Exposure Sensitivity Map landforms that are sensitive to coastal hazards and the potential impacts of sea-level rise. Adaptive Capacity Potential impact Describe landform types of the Illawarra and derive sensitivity rankings. Large swell at Flagstaff Point Evaluate Smartline and polygon mapping. Vulnerability Allen Consulting Group, 005 Seawall at Warilla Eroded beach dunes at Corrimal beach Vulnerability North Wollongong beach Flagstaff Point The National Coastal Vulnerability Assessment Smartline Maps (University of Tasmania) Department of Climate Change - first pass assessment of coastal vulnerability to the impacts of climate change. 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). Identify coastal ecosystems and infrastructure most at risk. Rely on geomorphic mapping. phases,. Smartline mapping (UTas). Polygon mapping (GA) Available through the OzCoasts website ( is a combination of the physical sensitivity, the assets at risk and the ability of society to cope with these risks (Harvey and Woodroffe, 0) (bedrock slope with soil) (dune) Broad tidally-defined and shore-parallel zones Lake Illawarra and Perkins beach

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. :50K Geology WA Dept. of Industry and Resources :00K Geohabitat Types Geoscience Australia Level Classification Scheme Coastal depositional environment, i.e. alluvial plain, estuarine plain, coastal barrier/backbarrier, shelf, bedrock feature, anthropogenic feature. Case Study: The Comprehensive Coastal Assessment Toolkit NSW Dept. of Planning Lake Illawarra to Seven Mile beach Level Level a Coastal geomorphic feature, i.e. beach, channel, dune, delta This is the primary field (:00K :5K). Coastal geomorphic feature detail, i.e. dune type. Will be mapped if additional information is available (:5K :0K). Level Sediment texture and lithology, i.e. mud/sand/gravel, carbonate, plutonic (:50K :00K). Level a Rock Type, lithology description i.e. basalt, sandstone, conglomerate Mapped where data is available (:00K :5K). Level Biota, i.e. mangrove, salt marsh, coral, seagrass Mapped where data is available (:00K :5K). Level 5 Substrate type CONSOLIDATED or UNCONSOLIDATED Reclassification Level Coastal Depositional Environment Reclassification Level Coastal Geomorphic Feature

3 Reclassification Level Biota Type Level 5 identification of consolidated (hard) and unconsolidated (soft) sediments. Line vs. Polygon Illawarra coast Polylines Stanwell 80 km S. of Sydney Store many attributes for a single spatial location (i.e. backshore, near shore, exposure described in one line segment). Allow simple GIS queries. Park 67 km long Narrow coastal plain Polygons Map the spatial extent that vulnerable landform units occupy, allows for modelling of coastal processes. Lake Illawarra Wave-dominated Over 00,000 people Pacific Ocean Seven Mile Lake Illawarra, NSW, geo-habitats Hardy Inlet, WA, intertidal landform type Smartline segmentation Rocky shore Coarse grained sand Cliffs & rocky shore Sediment plains 0 Plains (0o 6o) Gentle slopes (6o 0o) Landform types - intertidal Fine medium grained sand Dunes & dune ridges Rocky shore Coarse grained Artificial shoreline 0 Steep slopes (>0o) High cliffs (> 50 m) Fine grained Coastline

4 Landform types - profile Landform types - backshore Rocky shore & cliffs Sediment plains Dunes & dune ridges 0 Artificial structures 0 GIS queries - sandy sensitivity Moderate slopes ((6o - 0o) Steep slopes (> 0o High cliffed coast GIS queries - sandy sensitivity 0 = (fine sand) 0 (dunes) (low plains) 0 = 0 backed by dunes Sediment Plains (0o - 6o) 0 = = 0 = = = 7 (fine sand) (artificial) (low plains) (fine sand) (bedrock) (low plains) 00 m = 0 Dunes = backed by artificial structures = 7 = 5 = 5 backed by bedrock = Artificial = Illawarra sandy sensitivity = Fine-medium grained sandy shore () Coarse-grained sandy shore () Rocky shore () 0.0 landform types = Bedrock = Artificial structures () Dunes and dune ridges (0) 8.. Sediment plains (0) 7. Rocky shore or cliffs () 5 5 landform types Sensitivity

5 Shoreline segment exposure inland slope High cliffs () 0.0 Steep slopes () 6.7 Gentle to moderate.5 slopes () Low plains () Sheltered ().9 Semi-exposed () 7.8 Exposed () Sandy sensitivity for the Illawarra Sandy sensitivity Sheltered re-entrant but not a sandy shore (0) Re-entrant sandy shore backed by structures (7) Re-entrant sandy shore backed by plains (0) Open sandy shore backed by artificial structures (7) Open sandy shore backed by bedrock (5) Open sandy shore backed by dunes () Open sandy shores backed by plains (0) Low Moderate High Not a sandy shore (00) 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 5.9 % - moderate sensitivity 5.% - low sensitivity. % - non-sandy shores 7. % Bellambi/Woonona beach Future study: Investigate historic rates of shoreline movement Questions? 5