[pmurfe]

Lee,

I have done several models using LDD and the Hydrology module. There are some quirks/guidelines to adhere to, but I've had good results.

1. You have to have a surface. Be it 3-d contour lines, points, etc. you have to create a TIN (surface) to be able to output the data.

2. You can only use polylines with 2 or 3 verticies for your river sections. To date, I haven't found a way around this. The polylines have to be created from left to right as you are looking downstream.

3. Don't be confused by the "multiple section" command. Generally, you want to do the "single section" command and individually select each polyline (river station) starting from the most downstream river section to the most upstream river section.

4. Once the sections have been defined, you must provide some parameters for completion such as starting WSE, stream slope, Q, etc.

5. The output file from LDD is essentially a HEC-2 geometry file.

As with your Carlson software, you will still have to input your Manning's "n" values and put in the correct stream bank locations. You don't have to worry about the overbank distances. This is automatically done during the river station selection process.

This is a quick and nasty description. I apologize if I'm not filling in the blanks well enough.