Situational Awareness of Postfire Debris Flow Activity using Big Data

In semi-arid regions of the United States rainfall intensity thresholds are used to estimate when postfire debris flows may occur. Prior research has shown that postfire debris flows are highly correlated with short-duration rainfall intensity, and that short duration rainfall thresholds (e.g., 15-minute rainfall intensity) can be estimated based on wildfire and terrain attributes. Consequently, it is possible to determine possible debris flow activity in recent burn areas in the western United States by tracking rainfall rates using publicly available rainfall data. We have developed a software (FlowAlert) and an accompanying map dashboard that monitors when and where rain gages near burn areas cross rainfall intensity thresholds. The software runs continuously on a linux server, processing more than 2500 rain gages every two hours. When rainfall rates near a burn area are higher than a rainfall threshold, symbols are updated on a map indicating possible debris flow activity. Rainfall plots are also provided on the dashboard, and via email alerts for the gages that have crossed the rainfall intensity threshold. FlowAlert can be used for situational awareness to alert authorities of potential debris flow activity in remote areas. Additionally, the data stream produced by FlowAlert can be used by managers to adjust the rainfall intensity threshold in areas following storms based on observed activity. For example, if rainfall thresholds were crossed, but no debris flows were observed, managers may choose to increase the rainfall threshold to avoid warning fatigue.  This presentation will focus on the utility of the new FlowAlert software, and how it might be used for decision support in burn areas.