Journal Article

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

Johnson, David R., Michalek, Alexander T., Prein, Andreas F., Wang, Chao, Done, James M., Villarini, Gabriele

2025

Overview

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. Plain Language Summary This study examines how the timing and magnitude of median daily streamflows are projected to change across all streams in Alaska under climate change. Much of Alaska shows a shift in the peak timing to earlier in the year, with the highest increase in peak magnitude observed for the northernmost regions. 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. Overall, we provide an assessment of the changes in flood extent across Alaska under warming climate conditions. Key Points We perform hydrologic modeling across Alaska and assess the change in flood magnitude and inundation using km‐scale modeling of the climate Temperature and precipitation (temperature) shift hydrograph peak magnitude (timing) under pseudo‐global warming simulations for Alaska Higher precipitation and higher evapotranspiration compensate, resulting in only a small increase in flooding across Alaska

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Alaska / Awareness-raising / Climate change / Climate models / Climatic conditions / Creeks & streams / flood / Flood hazards / Flooding / Floods / Global warming / Hydrologic models / innundation / PGW / Precipitation / Precipitation-temperature relationships / Rivers / Stream discharge / Stream flow / Temperature