Converting a NEXRAD Rainfall Map into a Flood Inundation Map by ...

Once the hyetograph is defined (for each subbasin in this case) it can beentered into the HEC-HMS system manually (internal gage definition) or bymaking a reference to it through a HEC-DSS pathname record inside the flow filecontent (external DSS gage definition). The previous statement implies that ameteorologic file needs to be generated referencing the appropriate DSS recordscontaining the rainfall hyetograph for each subbasin.4.1.3.4 Writing the Gage FileAfter the HEC-DSS descriptors have been extracted from the geodatabasetable and the target HEC-DSS filename and directory location is established, theapplication writes the gage file (.gage) for HEC-HMS based on the subbasin’snames and using the extracted HEC-DSS pathnames (one per subbasin) anddirectory location. The main purpose of this file is to store a complete list of alltype of gages inside or outside the basin that could potentially be used by theHEC-HMS model setup. Some or all of the precipitation gages for example areused to define the meteorologic input of the model and depending on the type ofmeteorologic model to be used; the gages will need to be georeferenced by meansof geographic coordinates (the inverse distance weighting method in whichrelative position is needed). For the Map2Map implementation only the HEC-DSS filename and location with the specific DSS card pathname pointing to therainfall time series is needed.4.1.3.5 Writing the Meteorologic FileBy means of the DSSTSType table the application (GDB2HMSDSS scripttool) gets hold of the DSS descriptors needed for the exchange and the HMS input95