Mitigating debris flow hazard through a community designed warning system and citizen scientist operated sensor network

Abstract:

Debris flows are geomorphic processes that present significant hazards to mountainous communities resulting in hundreds of fatalities, globally, each year. As studies continue working towards predicting initiation and runout, debris flows remain difficult to forecast. We can, however, monitor debris flow triggering conditions, and use those to warn the public when they may present risk. Recent studies suggest that developing a people-centered, participatory warning system, one which relies on the user community for design input and system operation, will lead to greater system effectiveness and longevity. We are developing such a system in Sitka, Alaska, where an extreme rainfall event in August 2015 triggered over 40 debris flows, one of which was deadly. The public is engaged and contributing to this warning system though design contributions that are provided during yearly workshops hosted by experts in risk management (see Turner et al). Citizens also participate in data collection and analysis. Here we describe a citizen science monitoring effort to observe precipitation in which citizens operate and maintain a network of rain gauges called Sitka Mesonet. In addition to helping us acquire useful data, the Mesonet has been built to increase hazards awareness and response capability. We incorporated this network into one of stream gauges, meteorological stations, and soil moisture sensors (see Patton et al) to provide data that can be used to predict debris flow imminence. Thus far, the publicly available tipping bucket data reveals that microclimates throughout Sitka experience rainfall events at very similar times, though the magnitude of rainfall varies by site. Success of this program is demonstrated by the enthusiastic response by the public towards this monitoring effort as well as the independent application of the data by private citizens. Developing this warning system is an iterative process and the ways in which it is used will evolve as the community continues to provide input. Through this collaborative effort, we have set a community in motion to minimize the impacts of debris flows and increase local resilience in the face of natural hazards.