Decision-maker based flood risk response event maps

Most approaches of risk modeling only address the risk to infrastructure.  In this work a modeling approach for representing event-based response risk is presented. This model uses the preferences of flood decision-makers during flood response by surveying local emergency management officials from six states. To accomplish this, surveys were sent to over 450 flood emergency managers to determine what the response priorities of decision-makers are during flood disasters. The priorities were linked to geographic information to create maps of event-based risk for response. This fills a gap in the current literature on responding to flood disasters, because while risk has been discussed for other phases in the emergency management cycle, it is rarely discussed from a response perspective.

High Water Marks

The high water marks (HWM) and flood inundation maps are valuable datasets useful for calibrating floodplain engineering models used to generate flood hazard mapping and provide additional flood awareness and hazard identification. One of the limitations associated with HWMs and historic flood inundation maps is that the frequency of the associated events is often unknown. This is because flood frequencies are determined by the magnitude of the volumetric streamflow (discharge) associated with the water level that left a HWM. Obtaining the streamflow associated with a HWM can be done with the greatest confidence at a streamgage that has a documented relation of water level versus discharge (called a “rating”). Confidence decreases on a given “gaged” stream (stream that has a gage on its main stem) with distance upstream or downstream of the gage. For HWMs on streams with no gage at any point on the stream (“ungaged” stream), estimating the discharge and associated flood frequency can be very difficult. This project evaluates methods to compute or estimate flood frequencies associated with documented flood events on gaged and ungaged streams.

Collaborators: Association of State Floodplain Managers (ASFPM, The Polis Center