As I write this post the first waves from the tsunami that originated from the devastating 8.9 magnitude have reached Hawaii. The Honolulu metropolitan region is home to over 900,000 people and contains numerous businesses, and key pieces infrastructure, including the airport. By all accounts from the media the excellent alert system that our government has in place will prevent the loss of life. Predicting the significance of the tsunami's impact is difficult, but Honolulu is fortunate in that LiDAR was acquired back in 2009. Unlike traditional digital elevation models (DEM) that only represent the bare earth, LiDAR digital surface models (DSM) are a 3D representation of all features. When I came into work this morning I loaded in the LiDAR DSM for Honolulu into
Quick Terrain Modeler, draped on top of it the existing aerial imagery, and then ran some flood simulations for the
Honolulu International Airport (HNL). HNL is an interesting airport. It is literally on the Pacific Ocean, with its "Reef Runway" being the world's first major runway to be constructed entirely off shore.
The graphics below show what HNL would look like if the ocean levels were to increase by 5 meters.
Please note that these graphics are done for demonstration purposes only.
There is no indication that the sea level will rise by 5 meters, nor has this analysis been subjected to detailed quality assurance and quality control procedures.
Inundation mapping is far more complex than just raising the sea level. If you are looking for the official inundation maps please visit the the
Honolulu government web site. Here is a
nice article on how the updated inundation maps were generated using LiDAR. There is also an interesting report from
Spatial Informatics Group on the
The Protective Role of Natural and Engineered Defense Systems in Coastal Hazards that was prepared for HI. I hope that those communities affected by this tragedy are able to recover quickly.
5 comments:
Thank you Jarlath,this is excellent information and a useful visual of how LIDAR could help us with this very recent challenge. One quick correction, Honolulu airport's code is HNL, not HIA. Aloha!
Thanks for catching that Kevin, I made the correction. Glad to hear that there was little damage to 50th state!
Thanks Jarlath for this excellent work. Really appreciate your practical presentation on the flood simulation. I would like to get your views on building an application that provides the same simulation using open source GIS on the web platform. Would it be possible and what kind of resources do we need if we combine free and open source GIS solutions? Thanks in advance.
Thanks Jarlath for this excellent work. Really appreciate your practical presentation on the flood simulation. I would like to get your views on building an application that provides the same simulation using open source GIS on the web platform. Would it be possible and what kind of resources do we need if we combine free and open source GIS solutions? Thanks in advance.
I think a web based portal do this type of flood simulation based on LiDAR could be challenging for two reasons: 1) the geoprocessing and 2) data access. The first has to do with the fact that interactive flood analysis can be very RAM intensive. The second challenge has to do with the fact that access to LiDAR data sets collected by certain agencies (principally NGA and FEMA) is restricted under circumstances. That being said there was quite a bit of simulation done for the recent floods in Brisbane, although I could not find if it was an interactive online portal. I simple solution would be to cache the data for floods at various intervals, and serve that data up. This would be fast and simple. One could use any combination of Google Maps, GeoServer, Arc2Earth Cloud, etc.
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