reduced flow rate

[howertonengr]

I am using HEC1 with Hydrodynamic routing to model a creek. I have taken cross sections along many areas of the creek. The first time I ran my model I had very large cross sections with points that were way above the elevation I needed. I recduced the size of my cross sections to only include points near the creek and added about six more so I could study one area in better detail. When I did this my flow rate reduced from around 6000-8000 to around 2000-3000. I changed nothing other than the number of crosssections and deleted some of the points not in the area close to the water on existing ones. Any idea why this happened?

[Chris Maeder]

Check the amount of runoff coming from the subbasin. It is possible that the cross section is choking off the subbasin peak runoff by throttling what flow the cross section can handle.