We are trying to convert a previous FLDWAV model to HEC-RAS (to determine PMF for a dam). Being new to HEC-RAS, I have the following questions:
1. We are modeling unsteady state flow and used a flow hydrograph to set the upstream boundary conditions and a stage table to set the downstream boundary condition. Is this appropriate for a PMF study?
2. We have two incoming streams. Do I insert these as lateral hydrographs? Looks like the old FLDWAV model had inserted a constant flow for these tributaries.
3. When modeled in HEC-RAS as described above, I get negative flow for the x-section located in the upper third of the reach. I saw in another posting that this may be due to having too few x-sections. Is that true or are there other causes? Should I be concerned about this negative flow? Does it really represent water flowing in the opposite direction?
Thank you for assistance in advance.
1. We are modeling unsteady state flow and used a flow hydrograph to set the upstream boundary conditions and a stage table to set the downstream boundary condition. Is this appropriate for a PMF study?
2. We have two incoming streams. Do I insert these as lateral hydrographs? Looks like the old FLDWAV model had inserted a constant flow for these tributaries.
3. When modeled in HEC-RAS as described above, I get negative flow for the x-section located in the upper third of the reach. I saw in another posting that this may be due to having too few x-sections. Is that true or are there other causes? Should I be concerned about this negative flow? Does it really represent water flowing in the opposite direction?
Thank you for assistance in advance.