This is not the first time I've stumbled over this issue; it seems that I am unable to generate a correct drainage network model and the resulting catchments from full resolution (1m cells) LiDAR data. 

When I generalize the LiDAR dataset and fill sinks, all is good and I can easily create all that is needed, however I would like to produce a detailed site model for a large scale map and this is where I am having problems. 

I should point out that most issues occur in flatter areas but surely there must be a way to use full resolution data for say highway drainage models, etc.

I would like the drainage network to accurately follow the terrain but when I use the full resolution data the drainage network is often "disconnected" in areas where it should not be. There are also a lot of "orphan" or "go nowhere" segments. The resulting drainage network also does not appear to follow the terrain correctly. I would expect the "Flow Accumulation" algorithm to perform better. 

The workaround is to fill sinks but the resulting drainage network is obviously inaccurate when overlaid over data. The higher the sink value, the more inaccurate the drainage network becomes (network outside of clearly visible channels, etc.). 

I suspect my problem lies with data preparation; integer vs floating point raster, filling sinks correctly, etc. 

Can someone describe the correct methodology for doing this with Spatial Analyst?

*I am attaching a image with several obvious problem areas circled. Please note that there is actually a stream in what appears to be the main drainage channel. I added a very generalized version of the stream.*
![enter image description here][1]

 


  [1]: https://i.sstatic.net/n6QVB.jpg