Physical mechanics of aufeis growth

Abstract

All arctic travelers have encountered streams and braided rivers swollen with ice during the winter months. Numerous field measurements were made in an attempt to develop an understanding of the mechanics of aufeis growth. Piezometers were installed at several sites in central Alaska to measure the pressure variations of the fluid in the porous streambank. Time series analyses were utilized for correlating the variations in the observed pore pressures with climatic variables. It was concluded from the piezometer measurements of pore water pressure that subpermafrost groundwater or groundwater from nonpermafrost regions was the source of water for these ice deposits. Water from the active layer did not contribute to these accumulations of ice. Time series analysis revealed that pore water pressures started to increase following warming trends. A time lag existed between the start of a warming trend and the corresponding changes in pore water pressure; this time lag increased as the thickness of ice increased.