adding tributaries to existing reaches

[Ken Colgate]

Hi Chris,

I read the question from Greg Johnson on 08/16/02 and your response. My situation is a little different.

I'm getting warning messages that I have junctions with only two reaches.

When I modeled the main channel I divided it into logical reaches where there will be future inflows or outflows. I am now trying to put in the tributaries as data becomes available and want to put in zero flows from the tributaries that usually run dry.

I'm getting the impression that I shouldn't have pre-set junction points. Do you or anyone else know how to put in "new" tributaries that tie into "existing" junctions? Some of the "tributaries" will be just point sources of inflow or outflow. Is there a way to model "point sources" without having to model complete reaches with sections and such?

Thanks for your help,
Ken

[Chris Maeder]

Ken:

In HEC-RAS, you can define a lateral inflow at any cross-section in your model.

From the Steady Flow Data Editor, select the River Station (i.e., cross-section) that you want to define the additional (lateral) flow at. Then, click on the button "Add a Flow Change Location". HEC-RAS will add another row to the data editor with this cross-section ID, allowing you to define what the "total flow" (stream flow and additional lateral flow) is for downstream of this cross-section.

In this way, you will not have to define a junction and a tributary to define the additional lateral inflow, but can simply add it in as increased total flow in the river reach.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com