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Integrated electrical resistivity tomography (ERT) and self-potential (SP) techniques for assessing hydrological processes within glacial lake moraine dams

journal contribution
posted on 2023-05-20, 17:36 authored by Sarah ThompsonSarah Thompson, Kulessa, B, Luckman, A
Moraine dams can be inherently unstable, but effective assessment strategies remain poorly identified. We integrate electrical resistivity tomography (ERT) with electrical self-potential (SP) and lake-level measurements to investigate the structure of, and hydrological processes within, a moraine-dam complex adjacent to Miage glacier, Italy. This complex separates two meltwater lakes characterized by an efficient subterranean hydraulic connection. Our ERT data reveal a continuous free surface within the complex, whose morphology reflects the topography of the moraine complex akin to unconfined groundwater aquifers. SP data were corrected for spatial changes in the thickness of the upper unsaturated layer using principles of electrography. The residual streaming-potential map is consistent with Darcian flow of lake waters through the moraine complex, characterized by a negative-to-positive potential change from <-30 mV to >+70 mV. These electrical signatures are consistent with those generated by water seepage through earth dams in various non-glacial settings. Integrated electrical geophysical methods thus provided an inexpensive and unobtrusive evaluation of the hydrological properties of and processes within the moraine complex. Since spatio-temporal patterns of subsurface water flow critically affect the strengths of moraine sediments, such methods promise to be powerful in assessing the long-term stability of moraine-dammed glacial lakes.

History

Publication title

Journal of Glaciology

Volume

58

Issue

211

Pagination

849-858

ISSN

0022-1430

Department/School

Institute for Marine and Antarctic Studies

Publisher

Int Glaciol Soc

Place of publication

Lensfield Rd, Cambridge, England, Cb2 1Er

Rights statement

Copyright 2012 International Glaciological Society

Repository Status

  • Restricted

Socio-economic Objectives

Natural hazards not elsewhere classified; Expanding knowledge in engineering

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