Using Unmanned Aircraft Systems to Monitor River Ice Breakup in Support of Hydrologic Forecast Operations in Alaska

The annual spring breakup of rivers in Alaska brings the threat of flooding from ice jams to many communities.  The National Weather Service (NWS) and the Alaska Department of Homeland Security and Emergency Management have monitored Alaskan rivers during breakup using manned fixed-wing aircraft for several decades as part of the River Watch program. In recent years, advancements in temporal and spatial resolution of polar orbiting satellites have improved broad scale monitoring of river ice conditions and flooding. However, the satellite imagery does have some limitations: the grid cell size of satellite imagery often limits determination of ice presence to the largest river channels, the image collections are restricted to fixed times when satellite pass overhead, and cloud free days are required to obtain useable imagery.

In support of the National Oceanic and Atmospheric Administration (NOAA) Unmanned Aircraft Systems (UAS) Program, the NWS Alaska Region and the Alaska Center for Unmanned Aircraft Systems Integration (ACUASI) partnered to evaluate the use of an UAS to monitor ice conditions during the 2016 spring breakup of the Yukon River. The objectives of this mission were to examine the ability of UAS to enhance near-real-time, operational forecaster Decision Support Service, provide rapid response surveillance of river ice and/or flooding, and to validate and calibrate satellite-derived river ice and flood products. The Yukon River at Circle City was selected for the mission for several reasons: the community is on the road system; the River Watch team monitors this stretch of the Yukon River; the UAS data collection complements larger scale, manned fixed-wing in the area by the University of Alaska; and the community frequently experiences spring ice jam flooding. The NWS requested multiple flights over several days to observe pre-breakup ice surface signatures that may act as precursors to ice movement (breakup) and to improve lead-time for forecasting ice breakup, ice jams and flooding.

This presentation will discuss the results, limitations, and challenges of using UAS technology to monitor river ice conditions in support of hydrologic and flood forecast operations in Alaska. In addition, improvements and plans for future missions during the 2017 spring ice breakup of the Yukon River will be addressed.