To Determine the Base Flood Elevation on an Urban Area

First, review your scope of work that is in the contract; I presume it should contain level of effort needed to perform the analysis and what shall be included (Hydrology & limits of mapping). From there establish your plan to develop the H&H needed to map the base flood. I would recommend a FEMA Search first to determine what has been determined for the Zone A flood zone and then determine the validity of that data. Then local H&H Studies or your own hydrology based on your specific scope of work.

Step by Step for H&H:
Hydrology: Mapping/Topo, Soils, Land Use, Methodology
Hydraulics: Mapping/Topo/Survey, Hydraulic Method, Consider storm surge????
Documents: Prepare Technical Support Data Notebook in accordance with your local requirements

Real general; but, I do not know your scope. Hope this helps.

Sebast73-

I recommend contacting FEMA to get information on what modeling they will accept for this study. SCS method is not typically the first (or second) choice for establishing flow in FEMA flood studies. For hydraulics, HEC-RAS has been the preferred method for establishing water surfaces in channels. When you add the fact that you are dealing with a coastal city, coastal flooding can certainly play a factor. Coastal flooding has entirely different modeling vs. storm runoff models. You may want to consult with a firm who has experience with FEMA studies.

Thanks for the Posts guys, finally getting back to this. On my way to do some research.

Thanks for the input.