Remnant aufeis on the Katakturuk River

Photo of Katakturuk River in Alaska with aufeis.  Aufeis forms when overflowing water freezes as it encounters cold air during the winter. The aufies is created by a spring that occurs in the active floodplain of the Katakturuk River which creates the aufies field in the winter. This is why the ice appears to be by itself (away from flowing water) and also why it can last far into the summer. The main river flow is to viewer's left during the regular flow season and therefore does not eat away at the ice accumulation created overwinter. Aufeis is a critical source of water in northern Alaska, and its presence may help USGS better understand subsurface hydrology in a region with few wells.