Historic Glacier Change in the Western US: Database and Modeling

Portland State University, Portland OR

Investigators

Abstract

This proposal develops a comprehensive GIS database of historic glacier change in the American west, exclusive of Alaska. We will define the spatial extent and temporal variation of glaciers in the American west based on the historic record derived from topographic maps and from aerial and ground-based images stored in federal and state agency archives, university libraries, and in hiking clubs. We expect to find at least two extents at different times for every glacier in the west. In some well visited areas (e.g. Mt. Rainier, Glacier National Park) we will find many glacier extents over time. These data will be compiled in a GIS database from which the magnitude and rates of change will be derived. The database will be made publicly available via the world wide web for use by professionals, educators, and the general public. In addition to the shape files of glacier extent, we will include photographs and bibliographic references when available. This achievement alone will accelerate our understanding of spatial and temporal patterns of glacier change. Volume changes will be estimated, where topographic data are absent, through area-volume scaling equations. This is a critical step towards defining the effect of glacier mass wastage on stream flow and global sea level rise. We will also test whether a cellular automata approach can reasonably predict the location and geometry of individual alpine glaciers within a given alpine region. The model will be driven by climate and numerically grow glaciers to an equilibrium geometry on the known topographic surface using a set of rules based on a simplification of glacier physics.