Geospatial Techniques to Assess High Mountain Hazards: A Case Study on California Rock Glacier and an Application for Management in the Andes

Abstract

California rock glacier, located in the Sangre de Cristo Mountains of Colorado, was used as a case study to exemplify the geospatial techniques needed to assess geomorphic hazards in mountainous regions. Horizontal and vertical velocities from 1983 to 1998 were calculated using GIS and photogrammetric techniques, and GPS measurements from 2003 to 2008 were used to supplement photogrammetric measurements. From 1983 to 1998, horizontal rates of flow averaged 57 cm/yr (± 3 cm/yr) and vertical thinning averaged 30 cm/yr (± 7 cm/yr) near the head of the rock glacier. GPS measurements from 2003 to 2008 indicate an average horizontal velocity of 52 cm/yr (± 5 cm/yr) for seven points extending from the midsection of the rock glacier to the toe. When comparing mean velocities, the rock glacier has experienced an overall slight deceleration; however, a detailed spatial evaluation of flow indicates GPS points 5–7 show an increase in horizontal velocity from 2003 to 2008 in an isolated section of the toe of the rock glacier. Regional climate data suggest that slightly drier and warmer conditions existed from 2003 to 2008, which may allow ice near the toe to deform more quickly. This region also contains the end of a longitudinal furrow that may funnel and accumulate water in a slightly concave toe. The water could act as a lubricant between shear planes or may warm ice, and allow it to flow more quickly. Although the observed change in horizontal velocity is not significant compared to other rock glaciers that are accelerating to over 300 cm/yr, the analysis has identified a potentially sensitive region of the rock glacier that should be monitored in the future. Mountain hazards, in the form of catastrophic rockfalls, moraine dammed lake outburst floods, avalanches, slumps, slides or others may become more prominent in changing climatic conditions; the GIS, remote sensing, and GPS techniques utilized in this study can easily be replicated or enhanced with other spatial, spectral, or temporal data to evaluate the potential for hazards in mountainous environments. A geospatial application for the Andes is discussed. Increased awareness of hazards and hydrological implications associated with receding glaciers could lead to proactive public participation and implementation of adaptive management strategies designed to adjust to short-term climate change.