Flood modelling senario with lidar data

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01-24-2017 12:40 AM
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RobertBuckley1
Occasional Contributor

I am currently working on a small project which entails creating some flood senarios using newly current lidar data. However I have an issue with lidar data. The Lidar data which we have received contains reflections on the water surface so called specular reflections ( see attatchment beneath) which cause the water surface to have elevations where there are nearby trees and vegetation. In order to create a flood senario, we will therefore not be able to use the current water surfaces in the lidar data. How then will we be able to create flooding estimates in the water surface height is not reliable?

Does anyone have any information regarding how to "clean" these types of distortions? Or would my model somehow disregard the water surface anyway?

1 Reply
IanMurray
Frequent Contributor

Hi Robert,

A few questions are you points classified into classes(ground, low veg, high veg, overlap, non-ground, etc.)?  What program are you planning to use for your flood modelling?  What data type input will be using for the flood modelling(Las File, DEM, etc.)?  Are the specular reflection points classified as ground, are there points that are actually along the water surface beneath the reflection points(I can't tell from the image)?

I'm assuming you want to work with the bare earth only, so you will likely need to subset your LiDAR data into only ground classified points(If the points are classified).  If this does not remove the spurious reflection points, you may need to digitize the area that is the water surface that has the spurious reflection points, create a constant value raster for the approximate elevation of the water surface for that area, then burn that into any DEM you would need for modelling.