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

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.