Riverbank Erosion in the Colville Delta, Alaska

Monitoring Inter- and Intra-Seasonal Dynamics of Rapidly Degrading Ice-Rich Permafrost Riverbanks in the Lena Delta with TerraSAR-X Time Series

“…Thermal erosion is the removal of ice-bearing permafrost by the combined thermal and mechanical action of moving water [6,9], and is also the most effective process of permafrost degradation [10,11]. It dominates the reshaping of permafrost landscapes by the erosion of ice-bearing riverbanks [12,13], coastlines [9,14] and lake shores [15] and leads to the formation of retrogressive thaw slumps [7], as well as gullies and valleys [16]. Thermo-denudation is the combined influence of solar insulation and heat advection on the energy balance of the ground surface causing erosion above the water level [9].…”

“…Riverbank erosion in continuous permafrost is strongly influenced by the hydro-mechanical and thermal forces of water [9] but the magnitude and timing is determined by factors such as sediment type, snow and ice cover, air and water temperature, and wind [12]. Thermo-erosional niching is the undercutting of cohesive, ice-rich banks by water and is a prominent process of riverbank erosion [17] leading to rates of up to 19 m per year [11].…”

River meandering on Earth and Mars: A comparative study of Aeolis Dorsa meanders, Mars and possible terrestrial analogs of the Usuktuk River, AK, and the Quinn River, NV

“…Exposures of ice, either as ice wedges or massive bedded ice are common on eroding banks of larger rivers (e.g. Walker and Arnborg (1966), Walker et al (1987), Costard et al (2003), Walker and Hudson (2003), Rowland et al (2009)) and erosion of river banks is often attributed to be dominated by thermo-erosional niching (Walker and Arnborg, 1966;Lewellen, 1972;Scott, 1978;Walker et al, 1987;Costard et al, 2003;Gautier et al, 2003;Walker and Hudson, 2003). This suggests that cohesion introduced by interstitial or massive ice in river banks limits rates of bank erosion and might provide the bank stability necessary to favor meandering over braided stream patterns.…”

“…Scott (1978) suggests rates of bank erosion are commonly less than seasonal depth of thaw. On the other hand, in large rivers thermomechanical notching and attendant bank retreat can exceed 3-5 m, with extremes exceeding 8 m for an individual event (Walker et al, 1987;Walker and Hudson, 2003;Walker and Jorgenson, 2011). But average rates of bank erosion in bends of large rivers is more typically 0.9 m per year and less for cohesive banks, with local maximum rates several times higher (Walker et al, 1987;Gautier et al, 2003;Walker and Jorgenson, 2011).…”

“…In large arctic rivers and deltas lateral erosion generally occurs by notching of the lower parts of river banks and undermining and collapse or slumping of the more cohesive, frozen, and generally vegetated upper portions of the bank (Lewellen, 1972;Scott, 1978;Walker et al, 1987;Walker and Hudson, 2003;Walker and Jorgenson, 2011). Seasonal depth of thaw can reach 50 cm in coarse sediment, but can be only a few centimeters in cohesive sediment (Scott, 1978).…”