User needs assessment for postfire debris-flow inundation hazard products

First posted April 6, 2023 For additional information, contact: Director, Geologic Hazards Science CenterU.S. Geological Survey1711 Illinois StreetGolden, Colorado 80401Contact Pubs Warehouse Debris flows are a type of mass movement that is more likely after wildfires, and while existing hazard assessments evaluate the rainfall intensities to trigger debris flows, no operational assessment exists for identifying areas where they will run out initiation. Fifteen participants who work in wide range job functions associated with southern California postfire hazards were selected using purposive sampling unstructured interviews about useful characteristics needs debris-flow inundation assessments. The interview guide was developed by team social physical scientists following best practices engaging users. focused on target information could influence ongoing or not-yet-initiated research physics methodology. Following standard methods user assessment, audio from recorded, transcribed, analyzed thematic coding scheme. Participants reported as one multiple their reflect this breadth. Most organizations life property mandates, concerns impact people’s safety, ability populations egress, damage property. Common comments included, (1) need interpret context forecast rainfall—which typically different timeframes, 15 60 minutes, respectively; (2) provide scenarios show how changes under external factors such varying intensity; (3) tension between fully reflecting all sources uncertainty impacted high level precision needed determine evacuation zones order reduce fatigue. saw utility both low-resolution over large fine-resolution targeted small areas, noting identification pose an ethical challenge because some might be prioritized others. concerned posed continuum hydrologic hazards, including hyperconcentrated flows. Finally, recognized shrinking time window end fire season start wet makes production, interpretation, use rapid important challenging.