Making a terrain map with LiDAR data
Using free digital height data to work out where to locate the sail and explore the topography of the surrounding landscape.
Key to the concept of Flotilla is that the sails are located in locations that could potentially be inundated by the sea. In the case of Phase 2, that would be spread out across the North Somerset Levels.
Phase One will also be located in an area that would flood if sea defences didn’t exist. To check the exact height above mean sea level at the sail sculptures proposed location, I used LiDAR data. Using QGIS GIS software, it allows me to move the cursor across a map and tells me the exact height that spot is. (Google Earth can do similar but is a lot less accurate).
This will allow me to mark on the mast different levels the sea could come up to due to sea level rise, storm surges etc, as well as mark historic floods that have already happened.
LiDAR data, which is produced by firing a laser at the ground from a plane and measuring the time it takes, can also produce visual representations of the topography of a place. In the render below, the marine lake and Salthouse Fields can be clearly seen. The sail will be located almost dead centre in this image.
It also shows how the combination of the cliffs and sea wall protect the low lying park which would frequently flood during high spring tides if unprotected. The image at the top shows a wider view showing the estuary and the sea wall extending to the south of the high ground. This defence runs all along the Somerset coast. It can also be seen in the photo below.
The LiDAR data is provided by DEFRA for free download and QGIS is free to use open-source GIS software.
