This is the base flood model for the ChennaiFloodManagement.org project.
It is a hydrologic/hydraulic model that takes rainfall and terrain data as an input and produces flood maps as an output. Of course it gets more complicated than that, but that's the basics.
The model depends on the ANUGA open-source modelling solution, produced by the Australian National University and Geoscience Australia (hence ANU-GA). This package and documentation is available here: https://github.com/GeoscienceAustralia/anuga_core
A user-interface is currently under development. Contact david.kennewell@hydrata.com for more details.