Improving Forecasts of Glacier Outburst Flood Events

Suicide Basin is a glacier-fed lake that branches off Mendenhall Glacier in Juneau, Alaska. Since 2011, Suicide Basin has been collecting melt- and rainwater each summer, creating a temporary glacier-dammed lake. Water that accumulates typically gets released through channels that run beneath the glacier. These channels are normally blocked by ice, but if the water pressure gets too high the channel breaks open, rapidly draining the basin in what is known as an “outburst flood”. In past years, these events have led to flooding along Mendenhall Lake and Mendenhall River in the most heavily populated neighborhood of Juneau.

 

Because of the threats posed to infrastructure in the Mendenhall Valley, it is critical that scientists closely monitor and forecast outburst flood events. The goal of this project is to design a tool to improve forecasting of the timing and flood peak associated with outburst events from Suicide Basin. The forecasting tool will be web-interfaced and provide real-time monitoring data from a USGS streamflow gage in Suicide Basin. After the onset of an outburst flood event, the web tool will also provide continuously updated forecasts of the flood peak (including timing) that will be used by the National Weather Service and the City and Borough of Juneau to warn the public about closures and threats to life and property. Accurate forecasts will improve the process of initiating and implementing closures and evacuations in the Mendenhall Valley. This tool can also benefit other Alaskan communities that are subject to similar glacier lake outburst floods.