Monitoring groundwater storage in an alpine watershed in the Canadian Rockies using microgravity measurements
Abstract
Alpine areas form the headwaters of most major river systems in western North America. To estimate the response of mountain rivers to future climate warming it is critical to understand the water-storage capacity and other hydrogeological parameters of typical geological deposits within alpine watersheds, such as moraines and talus slopes. Because of logistical difficulties and environmental impact considerations, conventional hydrogeological techniques, such as drilling and piezometer installation, are rarely feasible in these environments. Here, we present the results of repeat high-precision gravity surveys that were used to gauge the spatial distribution of groundwater within a large moraine-talus field that plays a dominant role in transferring snow and ice melt to stream headwaters within the Lake O'Hara alpine watershed of the Canadian Rockies. An initial gravity survey comprising a network of 80 gravity stations over an area of 1500 x 1000 m was undertaken during July, soon after peak melting of the seasonal snow pack. The same stations were reoccupied in mid-September when the volume of groundwater within the moraine-talus field was much lower. Changes in gravity between the two surveys allow us to delineate localized regions of groundwater storage and to gain a first-order estimate of their volumes. We relate our observations to surrounding lake water-balance data and hydrogeological information gained from other geophysical datasets (ground-penetrating radar, seismic refraction, and electrical resistivity tomography) over the same area to establish a conceptual model for groundwater flow and storage within the moraine-talus field.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.H52B..06M
- Keywords:
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- 0920 EXPLORATION GEOPHYSICS / Gravity methods;
- 1200 GEODESY AND GRAVITY;
- 1829 HYDROLOGY / Groundwater hydrology;
- 1835 HYDROLOGY / Hydrogeophysics