Geoscience Reference
In-Depth Information
Chapter 5
Geospatial Techniques to Assess High Mountain
Hazards: A Case Study on California Rock
Glacier and an Application for Management
in the Andes
Jason R. Janke and Antonio Bellisario
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 veloci-
ties from 1983 to 1998 were calculated using GIS and photogrammetric techniques,
and GPS measurements from 2003 to 2008 were used to supplement photogrammet-
ric measurements. From 1983 to 1998, horizontal rates of flow averaged 57 cm/yr
(
7 cm/yr) near the head of
the rock glacier. GPS measurements from 2003 to 2008 indicate an average horizon-
tal velocity of 52 cm/yr (
±
3 cm/yr) and vertical thinning averaged 30 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 repli-
cated 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
