Ice-Dominated Deltas

Abstract:

River delta morphologies are often categorized into river-, wave-, or tide-dominated systems. Arctic deltas, however, are frozen for 8-9 months of the year and are strongly influenced by the presence of ice and permafrost. Here we argue that Arctic river deltas are ice-dominated systems, characterized by a strong seasonality, flashy and short-lived river floods, permafrost-limited channel migration, ice-mediated overbank flooding, abundant thermokarst lake cover, under-ice sediment transport creating extensive pro-delta deposits, and a short duration of marine reworking. We present results from remote sensing and numerical modeling experiments to highlight these unique features and processes present on Arctic deltas. We also put Arctic deltas in a global context by comparing their relative rates of wave, tide, and river sediment transport, rates of geomorphic change, and overall basin characteristics. Finally, we discuss the future transition from ice-dominated deltas to river-, wave-, or tide-dominated deltas in a warming climate and hypothesize the effects on delta aggradation, progradation, and hydrologic connectivity.