I am using the Hydrology tools (Flow Direction; Flow Accumulation etc.) to create a stream network from a 1m Lidar-derived raster DEM. The area has a railway running through it, with large embankments that have culverts under them to allow water flow upstream of the embankments to flow through downstream. However, the DEM does not recognise these culverts and converts the embankments to "dam walls", creating an incorrect streamflow network upstream of the embankments. Any ideas on how to overcome this?
Thanks very much.