Using remote sensing data for monitoring rock glacier distribution in the Bolivian Andes: Implications for future water supply
SALLY RANGECROFT*, DR. KAREN ANDERSON, DR. STEPHAN HARRISON University of Exeter *PhD student: [email protected]
Photo: GILPIN ROCK GLACIER, COLORADO http://www.summitpost.org/gilpin-rock-glacier/645639 Presentation outline
• Motivation for research
• Introduction to rock glaciers
• Methodology
• Study sites
• Preliminary results
• Future work Motivation for research
Annual temperature deviation from the 1961–90 average in the tropical Variations in the Earths surface temperature Andes (1°N–23°S) based on a in the past 1000 years (Mann et al., 1999) compilation of 279 station records over the past 60 years (Vuille and Mark, 2008) Motivation for research
IDRC, 2010 What is a rock glacier? RockGlobal glaciersestimate 40 - 60% ice under top layer of rock
“a tongue-like or lobate Locally important as stores of frozen body, usually of angular water, found worldwide boulders, that resembles a small glacier, generally occurs in high mountainous terrain’’
(Potter, 1972; Washburn, 1979) Steep front slope
Lobate or tongue Flow lines, ridges shaped and furrows No vegetation cover
No vegetation cover
Rock supply
Photograph acquired from fieldwork 2011 Research objectives
- How many rock glaciers are there in Bolivia? Google Earth - How big are they? Chacaltaya Glacier - What is their distribution?
- What is their ice content? Geophysical surveying - Water content? Field season 2012 La Paz
-What are their responses to Historical aerial recent climate change? photos, satellite - Comparison to ice glacier imagery, meteorological response? data
- What will be their future Climate projections, response to projected climate GIS change in Bolivia? Methodology
• Remote sensing data to initially identify and map rock glaciers in the Bolivian Andes: - Inventory using Google Earth
• Fieldwork : - to understand the geomorphology of Bolivian rock glaciers - to validate information derived from Google Earth - to obtain in situ digital photographs - collection of survey data (GPS, slope angle, transects of surface features) Bolivia: Study sites
Tuni Condoriri Chacaltaya Glacier
La Paz
La Paz Glacier ice coverage = 32% Rock glacier and other permafrost Results features = 7%
Blue outlines = Green boxes = permafrost field sites features identified studied 2011 Results 2: Using Google Earth
1000m 400m
0m 0m
Rock glacier in the South of Bolivia. Rock glacier in the Pampalarama Elevation ~4800m. 1km in length area. Elevation ~4800m Results 3: Fieldwork data
Rock supply
Compression ridges angular rocks without Striations on rocks = glacier lichens = activity status = derived rock glacier Frontal slope = 32° active? Preliminary data derived from Google Earth
Feature Frequency Rock glaciers 89 Other permafrost features 31 TOTAL 120 Feature aspect Frequency Percent Rock glacier Percent of total N 1 0.83 activity frequency NE 0 0 Active/inactive 80% E 1 0.83 relict 20% SE 39 32.5 S 27 22.5 Difference noticed in altitude between SW 34 28.33 active and relict rock glaciers W 11 9.17 e.g. Sajama: active: 5077m relict: 4880m NW 7 5.83 TOTAL 120 100% Google Earth validation
Altitude data 5400 R² = 0,994
5200 )
a.s.l 5000
4800
4600
4400
4200
Google Earthaltitude Google (m 4000 4000 4200 4400 4600 4800 5000 5200 5400 Handheld GPS altitude (m a.s.l) Coordinates collected 80
70 R² = 1 60 50 R² = 0,999 R² = 0,999 40 30 20
10 Google Earthcoordinate Google reading 0 0 10 20 30 40 50 60 70 80 Handheld GPS coordinate reading Future work
- How many rock glaciers are there in Bolivia? Google Earth - How big are they? Chacaltaya Glacier - What is their distribution?
- What is their ice content? Geophysical surveying - Water content? Field season 2012 La Paz
-What are their responses to Historical aerial recent climate change? photos, satellite - Comparison to ice glacier imagery, meteorological response? data
- What will be their future Climate projections response to projected climate GIS change in Bolivia? Thank you for listening
ACKNOWLEDGEMENTS
NERC John Macgrath at Oxfam Simon Ticehurst at Oxfam, Bolivia Paula Pacheco and Ana Paola Castel at Agua Sustentable, La Paz, Bolivia