Brian A. Ebel 2024 <div>Upper magnitude limits and scaling with basin size for post-wildfire floods are unknown. An envelope curve was estimated defining post-wildfire flood upper limits as a function of basin area. We show the importance of separating peak flows by floods versus debris flows. Post-wildfire flood maxima are a constant 43 m³<span>&nbsp;</span>s⁻¹<span>&nbsp;</span>km⁻²<span>&nbsp;</span>for basins from 0.01 to 23 to 34 km²<span>&nbsp;</span>and then declining with added basin area according to a power law relation. Intense rainfall spatial scaling may cause the envelope curve threshold at 23 to 34 km². Post-wildfire flood maxima are smaller than unburned flood maxima for similar basin area. Rainstorm comparisons indicate that post-wildfire floods are triggered by smaller precipitation depths than unburned floods. Post-wildfire exceptional floods are driven by extreme rainfall rates, in contrast to post-wildfire debris flows. Runoff rates for post-wildfire envelope floods are consistent with infiltration-excess runoff. Future increases in precipitation intensity or wildfire frequency and extent could increase post-wildfire flood upper limits.</div> application/pdf 10.1126/sciadv.adk5713 en American Association for the Advancement of Science Upper limits for post-wildfire floods and distinction from debris flows article