Elevation data and modelling

Coastal areas will be vulnerable to inundation from sea level rise in different ways, due to the topography of the landscape. Highly accurate mapping of the ground surface topography or elevation of the landscape is essential to highlight low-lying areas close to the coastline that are at risk of inundation.

Digital elevation models (DEMs) are three-dimensional digital representations of the ground surface topography that show the elevation of the landscape. They represent a 'bare earth' model that excludes vegetation and buildings.

The quality of DEMs has improved rapidly over the last decade with the emergence of new technology and approaches. Today most high resolution DEMs are captured using airborne stereo imaging, radar or LiDAR (Light Detection and Ranging) technologies. The quality of DEMs is generally expressed in terms of horizontal and vertical accuracy (or resolution) and horizontal spacing of the grid. Most organisations currently investing in coastal DEMs in Australia are capturing airborne LiDAR data with vertical accuracy of 10-15cm and horizontal grid spacing of 1-2m.

ANZLIC – the Spatial Information Council has been tasked with coordinating the development of the National Elevation Data Framework (NEDF) with the support of the State and Territory jurisdictions and the Australian Government; and in particular Geoscience Australia and the Cooperative Research Centre for Spatial Information (CRCSI). The NEDF is being developed to optimise investment and access to existing and future spatial information data collections and ensure this investment is directed to policy and operational needs across national, state/territory and local levels.

The NEDF-Portal has been developed to provide easy web access to a wide range of digital elevation data and derived products for public good use. The Portal allows users to search, discover, view, licence and take delivery of elevation and related data products. It is based on the latest web services technologies, and will be the first system of it's type offered by government in Australia providing access to terabytes of data worth many millions of dollars.

The Australian Government, through the Department of Climate Change and Energy Efficiency's Urban Digital Elevation Modelling in High Priority Regions (Urban DEM) project, has funded the acquisition and processing of high resolution elevation data of priority coastal areas in collaboration with State, Territory and Local Governments. The Urban DEM project is a significant vehicle for the implementation of the NEDF. The Urban DEM project is managed by the CRCSI in collaboration with Geoscience Australia. The Urban DEM project data can be accessed through the NEDF-Portal.

A LiDAR DEM over a coastal area in Sydney, NSW.
A LiDAR DEM over a coastal area in Sydney, NSW.
     
The same area depicting contours derived from the DEM over an aerial imagery. 
The 2m and 10m elevation contours are highlighted showing significant development below 2m.
The same area depicting 2m and 10m elevation contours
derived from the DEM over an aerial imagery.

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