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

4.1.9.1 Opening the HEC-DSS fileThe first thing done by the GDB2RASDSS script tool is to open orgenerate the HEC-DSS file that stores the streamflow records for the new HEC-RAS input configuration. The ZOPEN DSS subroutine is used for attaching thenew or existing DSS file to the GDB2RASDSS application and also for obtainingbasic information from the file that allows the application to write new records toit. As mentioned before, the ZOPEN is the first DSS subroutine to be called wheninterfacing with the HEC-DSS system. Again, the DSS file does not need to existbefore the ZOPEN subroutine is called and it will be created if it is not present.4.1.9.2 Reading Time Series InformationThe next section of the application is in charge of reading the Arc Hydrotime series table and the DSSTSType with all the HEC-DSS descriptors for eachflow change location. By reading this information the application is able to writeinto a new or existing HEC-DSS file, and write the new flow file based on thenew flow hydrographs and for the HEC-RAS setup.The application reads the DSSTSType table to get all the DSS descriptorsfor each pathname containing records for a flow change location from the DSScatalog. The DSS descriptors (Figure 3.21) are stored in a 2-D array in which thefirst dimension contains each flow change location point and the seconddimension contains each of the needed DSS descriptors. The DSS descriptorsneeded for the writing of records into a HEC-DSS file are described in Table 4.9.139