Freely available DEM s include buildings and trees and their resolution is 30m, most of time these DEM can't capture the low lying areas within highly dense urban areas. I think there may be some freely available DEM which can avoid this problems or there may be some methodology which can correct these problem and provide more accurate result for urban inundation area from a storm event. If anybody have any information regarding DEM or correction methodology please suggest me.
Dear Sasanka
In my expereince there are no freely available DTMs that can be used to undertake flood modelling of urban areas. As you correctly state that best DTMs that are available are basedon a 30 m gird and are no appripraite for carryying out urban flood studie. In my expereince 30 m DTMs based on staelitte data are often inappropraietly used by practitioners. There are no suitable methods suitable to improve the accuracy of these DTMs. The only answer is to procure a more accurate source of topographic data via for example a LiDAR survey at an appropraite grid size (e.g. 2 m or 5 m) with a suitable vertical accuracay e.g. +/- 200 mm.
I hope that this is of help.
Darren
Dear Sasanka,
Well, there is no freely available DEM (High resolution) that can be used for urban flood modelling.If you really want to then use ALOS PALSAR DEM Data (Resolution 12.5 m). It will be helps better.
best wishes
Hello there,
To solve the problem, perhaps you can calibrate the DEM using elevation data from secondary sources such as gps, construction map.
I think you may download 12.5 m DEM from alaska website, they have provided this under policy of NASA, hope it works will