Addition Electricity Circuits Symbols On Dc Voltage Schematic Symbols Flood hazard comes from different sources, including: riverine (or fluvial) flooding, stormwater (or urban) flooding, and coastal flooding. Natural infrastructure can play a role for each of these. Related to stormwater flooding - the focus of the InVEST flood risk mitigation model, natural infrastructure operates mainly by: reducing runoff production, slowing surface flows, creating space for water (in floodplains or basins). The InVEST model calculates the runoff reduction, i.e. the amount of runoff retained per pixel compared to the storm volume. It also calculates, for each watershed, the potential economic damage, by overlaying information on flood extent potential and built infrastructure.