Use of unmanned aerial vehicles and stakeholder-driven knowledge co-production enhance forecasting of the Suicide Basin glacier lake outburst flood in Juneau, Alaska

Abstract:

As climate warms in northern high latitude regions, small, fast-responding, tributary glaciers detach and retreat from larger trunk glaciers. Glacier-dammed lakes commonly form in the basins formerly occupied by these tributary glaciers, and occasionally drain rapidly, producing glacier lake outburst floods (GLOFs). Every year since 2011, Juneau Alaska has been impacted by a GLOF originating from Suicide Basin, a partly glacierized marginal basin of the Mendenhall Glacier. These floods cause inundation and erosion in the heavily populated Mendenhall Valley, with modest impacts to infrastructure so far. The focus of this project is to use a suite of on the ground and remotely sensed data collection methods to monitor and predictively model the annual GLOF from Suicide Basin. In particular, unmanned aerial vehicles (UAVs) have been used extensively to survey and map the basin as it fills and drains. During 2018 and 2019, approximately 30 M m³ of water was released from Suicide Basin in the course of a 4-5 day flood event.

Because of the pronounced risk to property and infrastructure, the project team has worked diligently to develop relationships with a variety of stakeholders including the City and Borough of Juneau, the National Weather Service, the US Forest Service, the US Geological Survey, the Alaska Division of Geological & Geophysical Surveys, and impacted Juneau citizens. Collaboration amongst these groups has facilitated the co-production of actionable forecast models and monitoring tools that directly benefit a broad variety of stakeholders. As examples, Juneau citizens can track real-time monitoring efforts in Suicide Basin through a multi-agency website developed for this project, and National Weather Service Forecasters can use statistical models that account for water storage in the basin to produce continuously updated real time estimates of the peak and timing of the GLOF. Looking to the future, GLOF estimates become increasing complicated; thinning of the ice dam across Suicide Basin will reduce water storage in the basin, however, declining ice volume in the basin and longitudinal lake expansion will increase water storage capacity. Ultimately, we expect that GLOFs from Suicide Basin will continue to impact Juneau for at least another decade.