  Flood-related risks to people and property are expected to increase in the
future due to environmental and demographic changes. It is important to
quantify and effectively communicate flood hazards and exposure to inform the
design and implementation of flood risk management strategies. Here we develop
an integrated modeling framework to assess projected changes in regional
riverine flood inundation risks. The framework samples climate model outputs to
force a hydrologic model and generate streamflow projections. Together with a
statistical and hydraulic model, we use the projected streamflow to map the
uncertainty of flood inundation projections for extreme flood events. We
implement the framework for rivers across the state of Pennsylvania, United
States. Our projections suggest that flood hazards and exposure across
Pennsylvania are overall increasing with future climate change. Specific
regions, including the main stem Susquehanna River, lower portion of the
Allegheny basin and central portion of Delaware River basin, demonstrate higher
flood inundation risks. In our analysis, the climate uncertainty dominates the
overall uncertainty surrounding the flood inundation projection chain. The
combined hydrologic and hydraulic uncertainties can account for as much as 37%
of the total uncertainty. We discuss how this framework can provide regional
and dynamic flood-risk assessments and help to inform the design of
risk-management strategies.
