Sinks in Arc Hydro

[JeffBlack]

Hello, I have a general question about sinks in Arc Hydro. I have a DEM and I am trying to impose known lakes and streams (in the form of shapefiles from the NHD dataset) into it.

I am confused about what a sink really is. I understand that it is a low point in the DEM, so are all the lakes considered sinks? I am just a little confused about what a proper workflow would be. I am thinking it would be level the DEM, then burn in the streams, then fill sinks, then do a flow direction with sinks, using the lake shapefile as sinks? Any guidance would be appreciated greatly.

Thanks,

[MarkBoucher]

You have the right work flow.

A sink is a grid cell that is lower than all the grid cells around it in the DEM. In a DEM this can happen just about anywhere since the DEM is usually an average of the spot (survey shots or LidAR) elevations or interpolated between contours (polylines) and in the averaging or interpolating you can get a local low grid cell. If you don't fill the sinks, then the flow direction grid created from the DEM will "stop" in the middle of nowhere, so to speak.

The link below my signature is a forum thread that has several tips on the Arc Hydro process.