Precipitation- and Temperature-Driven Future Changes to Flooding in Alaska

Examining large-scale projected changes in streamflow and flood extent (e.g., inundation) for Alaska is essential for raising awareness of flood hazards under a changing climate and supporting broad-scale adaptation planning. Therefore, we examine projected changes in peak streamflow timing and magnitude using a physically based hydrologic model. For model inputs, we utilize climate simulations conducted at 4-km horizontal grid spacing over Alaska from 2005 to 2016, providing a historical and future pseudo-global warming scenario. Analysis of hydrographs reveals the peak timing shifts slightly earlier in the year for most of Alaska's streams. The change in peak magnitude is more heterogeneous across the state, with the northernmost region showing the highest projected increases. The changes in timing are driven by temperature, while precipitation and temperature drive the changes in magnitude. These changes are then transformed into inundation maps, showing a similar albeit more muted pattern compared to the changes in magnitude.