When we set out to design the latest generation RMS High Definition (HD) flood loss models we identified five key challenges:
a) Resolution: Neighboring properties separated by a few feet in elevation can have dramatically different flood risk costs. However, the finer the model resolution, the bigger the hazard and loss files — and the slower the modeling. We needed an objective way of determining the best trade-offs around model resolution.
b) Duration: Once groundwater levels are raised, more precipitation can set off another round of flooding. The climatology can persist, bringing;
- a succession of storms on the same path, or
- a fixed long lasting atmospheric river, or
- a procession of rain bands from a stalled circulation parked at the coast as from Hurricane Harvey.
Flooding episodes can endure for days and weeks, but reinsurers want a predetermined definition of event duration. The model needed to provide the flexibility to explore how event duration affects results.