I got Flood hydrograph from rainfall data by HEC-HMS software. In this model there have no River flow data. Now I have to make a inundation map from that hydrograph by HEC-RAS for my study area. But I am confused to setup the boundary condition on 2D flow area. Since the hydrograph generated from rainfall so where and how can I set it in HEC-RAS?
I have attached a image for better understanding.