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| Titel |
Groundwater flow and storage within an alpine meadow-talus complex |
| VerfasserIn |
A. F. McClymont, M. Hayashi, L. R. Bentley, D. Muir, E. Ernst |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 14, no. 6 ; Nr. 14, no. 6 (2010-06-01), S.859-872 |
| Datensatznummer |
250012328
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| Publikation (Nr.) |
 copernicus.org/hess-14-859-2010.pdf |
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| Zusammenfassung |
| The different types of geological deposits and rock formations found in
alpine watersheds play key roles in regulating the rate and timing of runoff
to mountain rivers. Talus and alpine meadows are dominant features in these
areas, but scant data exist for their capacity to store and transmit
groundwater. To gain further understanding of these processes, we have
undertaken a combined geophysical and hydrological study of a small (2100 m2)
alpine meadow and surrounding talus within the Lake O'Hara
watershed in the Canadian Rockies. Several intersecting ground-penetrating
radar (GPR) and electrical resistivity tomography (ERT) profiles and a
seismic refraction profile were acquired to map the thickness of the talus
and to image the topography of the bedrock basin that underlies the meadow.
From analysis of the GPR and seismic profiles, we estimate that the talus
deposits are relatively thin (<6 m). Combined interpretations from the
GPR and ERT data show that the fine-grained sediment comprising the meadow
basin has a total volume of ca. 3300 m3 and has a maximum thickness of
ca. 4 m. Annual snow surveys and stream gauging reveal that the total input
volume of snowmelt and rainfall to the meadow basin is several times larger
than its groundwater storage capacity, giving rise to low total-dissolved
species concentrations (14–21 mg/L) within the meadow groundwater.
Observations from four piezometers established on the meadow show that the
water table fluctuates rapidly in response to spring snowmelt and
precipitation events but otherwise maintains a relatively stable depth of
0.3–0.4 m below the meadow surface during summer months. A slug test
performed on one of the piezometers indicated that the saturated hydraulic
conductivity of the shallow meadow sediments is 2.5×10−7 m/s.
We suggest that a bedrock saddle imaged underneath the southern end of the
meadow forms a natural constriction to subsurface flow out of the basin and
helps to maintain the stable water-table depth. |
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