ACKNOWLEDGMENTS CLOUD COMPARE ANALYSIS OF BUSHFIRE RISK IN PENNESHAW Catherine Fitzmaurice a1766463 Class REPRESENTATION III 2021 Tutor Carlos Bartesaghikoc LInk to Sketchfab: https://sketchfab.com/3d-model s/3cdd2619a0884ad38448c426195ffe35
University of Adelaide Bachelor of Architecture and the Built Environment
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CONTENTS 1. Acknowledgements 2. Contents INITIAL RESEARCH
3. Introduction 5. Climatic Information ASSEMBLY
ANALYSIS
8. Colouring the Site
7. Topography Analyisis 8. Canopy Height Calculations
REASSEMBLY
9. Final Model Modifications 12 Final Model 14. Reference
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INTRODUCTION
level 4: High Risk level 3: Medium Risk Bushfire Safer Places
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INTRODUCTION Government Bushfire Risk Assessment
The Australian Government has been closely observing the concerning increase in weather extremes, a result of climate change, which has been resulting in longer and more devastating bushfires nationwide. Climatic changes such as longer heatwaves, higher temperatures, less rainfall and increased droughts. Most recently the bushfires in Kangaroo Island in the summer of 2019- 20 saw 49% of the island burn. Although bushfires play an important part of the natural ecological cycle in initiating seed germination, these fires are now the biggest recorded historically for the island. An aftermath of a severely compromised wildlife with major loss of natural habitat for several endangered animals. The destruction of key tourism infrastructure and parks removed the island’s key economy.
This analysis is an investigation into Penneshaw, unaffected by the recent fires, to assess its potential bush fire risk. Taking into consideration how the topography, climatic conditions and vegetation interact to create bushfire weather. Highlighting any concerning connections to local residential properties, key habitats and access routes in case of emergency.
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SITE ANALYSIS
Allocasuanna Forest and Woodland Eucalyptus Mallee Forest and Mallee
Vegetation Types The surrounding vegetation is classified as Eucalyptus Mallee Forest. Generally wid-spread eucalyptus trees with dense under stories. They are among one of the most fire prone plant communities in semi-arid and arid zones.
Bushfire Conditions:
- Fuel Loads - Fuel Moistures - Wind Speed - Slope Angle - Humidity - Temperature
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Dry Conditions Rainfall in the summer is very unreliable, and in combination with the island’s sandy soils that do not retain ground water, there is low fuel moisture. Humidity stay low all year which increases evapouration of the soil and vegetation. Creating conceringly dry conditions. However temperatures during the summer months generally stay between 21 - 24 degrees. Unfortunately in the last 30 years there has been an increase from 5 to 15 days that are over 35 degrees. This is increasing the number of high risk fire days.
Wind Speed Jan-March Attention should be payed to speeds that above 12km. There are concerning southernly summer gails.
ASSEMBLY Colouring the Site: Combining Point Clouds The LiDAR spans were retrieved from ELVIS, locating Penneshaw and downloading the multiple point clouds for the site. Using Cloud Compare to stitch these data sets together as one, and then segmenting to isolate the desired perameters for the site analysis.
Apply Colour Once site parameters were defined, the corrosponding statelite image found on Google Earth was then georeferenced using the Quick Map Service tool on QGIS. Then using the LasColor tool to combine the segmented point cloud and the georeferenced image to colour the site.
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ANALYSIS Topography Anaylsis Using the Cross Section tool in Cloud Compare to create alternating 50 metre sections through the Eastern half of the site that contains the dense vegetation to further anaylise the topography. We can begin to identify any extreme inclines that would accelerate bushfires.
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Apply CSF Filter to extract relief points. Subsample ground points.
ANALYSIS
Tree Heighty Anaylsis
Create a mesh of the ground points using the poisson surface reconstrcution tool. Reduce scaler range to the tree canopy and export scaler field in z coordinates. Using the distance computation tool to then calculate the difference between the mesh ground level and tree canopy z coordinates. Once again adjust the scaler range and export to increase the tree canopy height gradient.
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REASSEMBLY
REASSEMBLY Final Model Modifications
Collating the topography, vegetation type and canopy height analysis to determine a new focused site that is identified to be at the most at risk for bush fires. This is determined by the understanding that where the tree canopy is the highest and most dense, we can identify the most mature trees. These pose a risk as they amount to more fuel for a fire and in the case of a lightening storm, the cause for the 2019 fires, these trees being the tallest are the most vulbnerable. To emphasise this pont in the final model, a selection of tallest heights is extracted in the red. Then using the Shadvis tool to redefine the tree canopy for better clarity and a more defined range of colour. This canopy is translated up to separate the selection from the base model. A subsampled verion is then translated down to create a trail. The final model required to be heavy subsampled and reduce in size inorder to be accomodated by the online visualisation tools.
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FINAL MODEL
In conclusion the model identifies a residential area that is at the highest risk in case of a bushfire. Surrounded by the highly flammable eucalyptus mallee woodlands located on a steep incline that is vulnerable to strong southernly summer winds. In case of a bushfire, the extremely dry conditions would make the dense vegetation a large fuel load, while the incline would accelerate the burn. Although Penneshaw has emergency guidelines in place, the increasing likelihoods of bushfire puts the whole town at risk year after year.
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References Arcgis.com. 2021. Kangaroo Island Bushfire 2019-20. [online] Available at: <https://www.arcgis.com/apps/Cascade/index. html?appid=ef29c850d8e34e98a8307dbdfe0aaaab> [Accessed 2 April 2021]. Bom.gov.au. 2021. [online] Available at: <http://www.bom.gov. au/climate/climate-guides/guides/049-Kangaroo-Island-SAClimate-Guide.pdf> [Accessed 2 April 2021]. Environment.gov.au. 2021. MVG 14 – Mallee woodlands and shrublands. [online] Available at: <https://www.environment. gov.au/system/files/resources/2edcda80-d9b7-49d4-9e9736236b91e9f9/files/mvg14-nvis-mallee-woodlands-andshrublands.pdf> [Accessed 2 April 2021]. Ga.gov.au. 2021. Bushfire | Geoscience Australia. [online] Available at: <https://www.ga.gov.au/scientific-topics/community-safety/ bushfire> [Accessed 15 March 2021]. Location.sa.gov.au. 2021. Location SA Viewer. [online] Available at: <http://location.sa.gov.au/viewer/?map=hybrid&x=140.54624&y=32.85173&z=6&uids=25#> [Accessed 2 April 2021]. Spatialwebapps.environment.sa.gov.au. 2021. Nature Maps. [online] Available at: <http://spatialwebapps.environment.sa.gov. au/naturemaps/?locale=en-us&viewer=naturemaps> [Accessed 17 March 2021]. WorldWeatherOnline.com. 2021. Penneshaw Monthly Climate Averages. [online] Available at: <https://www.worldweatheronline. com/penneshaw-weather-averages/south-australia/au.aspx> [Accessed 2 April 2021].
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