Aufeis Formation and Remediation

Jarvis Creek in Central Alaska flows through the Donnelly Training Area of Fort Wainwright. Low permeability moraine deposits which abut Jarvis Creek may be a factor leading to significant aufeis formations which can block spring rain and snowmelt. When severe, this blockage can cause the flow in Jarvis Creek to divert out of the main flow channel and into the overbank areas and through the Battle Area Complex (BAX) in the Donnelly Training Area. Field observations of the aufeis formation process, its extent, and the impact on flooding of Jarvis Creek and the adjacent BAX were conducted during the winters of 2006–07, 2007–08, and 2008–09. Trenching the aufeis was also used during these three winters to prevent flooding by providing a relief channel for the flow. The aufeis changes continuously throughout each winter and displays wide variability in extent and thickness from winter to winter, which presents difficulties to the planning and effective use of trenching to control flooding. A two-dimensional shallow flow model (ADH) was developed for Jarvis Creek and the major part of the Donnelly Training Area that floods to investigate two proposed flood control alternatives: an 800-m berm and a 3100-m berm. Both berm options would intercept the flow out of Jarvis Creek and return it to the main channel and were found to provide a more reliable flooding solution than the annual trenching operations.