I was wondering if there is a way to feed live flow data into HECRAS either directly or via DSS, and also a way to export modelling results as a continuous feed to be picked up by a webpage
There is a way to do this. HEC has a software called RTS (CWMS non-public version) that you can set up to grab data from a website, enter it into HEC-RAS, and map the floodplain.