Estimation of erosion, deposition, and net volumetric change caused by the 1996 Skeiðarársandur jökulhlaup, Iceland, from Synthetic Aperture Radar Interferometry

Authors

  • Laurence C. Smith,

  • Douglas E. Alsdorf,

  • Francis J. Magilligan,

  • Basil Gomez,

  • Leal A. K. Mertes,

  • Norman D. Smith,

  • James B. Garvin


Abstract

Using repeat-pass satellite synthetic aperture radar interferometry, we develop a methodology to measure flood-induced erosion and deposition and apply it to a record 1996 glacier outburst flood (jökulhlaup) on Skeiðarársandur, Iceland. The procedures include (1) coregistration of backscatter intensity images to observe morphological differences; (2) mapping of interferometric phase correlation to identify preserved and modified surfaces; and (3) construction, correction, and differencing of pre-jökulhlaup and post-jökulhlaup topography. Procedures 1 and 2 are robust and should be widely applicable to other fluvial environments, while procedure 3 is complicated by uncertainties in phase measurement, baseline estimate, and atmospheric effects. After a correction procedure involving interpolation of digital elevation model elevation differences across low-correlation areas, we find ∼4 m of elevation change are required to calculate volumes of erosion or deposition. This condition was satisfied for the 40 km2 proglacial zone of Skeiðarársandur, where we estimate +38×106 m3 of net sediment deposition along the ice margin, −2 ×106 m3 of net erosion in channels downstream, and a total net balance of +13 × 106. These estimates are supported by field observations and survey data collected in 1997.

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