Hydrologic and geomorphic changes resulting from episodic glacial lake outburst floods: Rio Colonia, Patagonia, Chile

Abstract

Glacial lake outburst floods (GLOFs) are a prominent but poorly understood cryospheric hazard in a warming climate. We quantify the hydrologic and geomorphic response to 21 episodic GLOFs that began in April 2008 using multitemporal satellite imagery and field observations. Peak discharge exiting the source lake became progressively muted downstream. At ~40–60 km downstream, where the floods entered and traveled down the main stem Rio Baker, peak discharges were generally < 2000 m3 s−1, although these flows were still >1–2 times the peak annual discharge of this system, Chile's largest river by volume. As such, caution must be applied to empirical relationships relating lake volume to peak discharge, as the latter is dependent on where this observation is made along the flood path. The GLOFs and subsequent periods of free drainage resulted in > 40 m of incision, the net removal of ~25 × 106 m3 of sediment from the source lake basin, and a nonsteady channel configuration downstream. These results demonstrate that GLOFs sourced from low‐order tributaries can produce significant floods on major main stem rivers, in addition to significantly altering sediment dynamics.

Multidecadal Geomorphic Evolution of a Profoundly Disturbed Gravel Bed River System—A Complex, Nonlinear Response and Its Impact on Sediment Delivery

“…This new phase space diagram demonstrates lateral adjustments dominate most of the conceptual phase space domains representing geomorphic adjustments in alluvial rivers. The dominance of lateral over vertical adjustments is consistent with channel evolution observations across a broad array of alluvial systems (e.g., Gurnell et al, ; Jacquet et al, ; James, ; Lauer et al, ; Mertes et al, ; Vericat et al, ).…”

Seasonal Changes in Carbonate Saturation State and Air‐Sea CO2 Fluxes During an Annual Cycle in a Stratified‐Temperate Fjord (Reloncaví Fjord, Chilean Patagonia)

“…In coastal areas, the carbonate system of surface waters is modulated mainly by heating and cooling (e.g., DeGrandpre et al, 2002), production and respiration (Burgers et al, 2017;Cox et al, 2015;Feely et al, 2010;Gattuso et al, 1998;Hales et al, 2005), freshwater runoff (Harris et al, 2013;Jacquet et al, 2017;Krauss et al, 2018), transport of allochthonous nutrients and organic matter (Bhatia et al, 2013;Silva et al, 2011;Tiwari et al, 2018), surface stratification, and advective processes such as upwelling (Beitzel Barriquand et al, 2015;Burgers et al, 2017). Some of these factors play important roles in fjord systems (Jolivet et al, 2015).…”

Dam type and topological position govern ice-marginal lake area change in Alaska and NW Canada between 1984 and 2019

“…These lakes can impact human societies in a multitude of ways, ranging from water resources (Immerzeel et al, 2020) and tourist attractions (Wang and Zhou, 2019;Welling et al, 2020) to destructive and lethal hazards (Carrivick and Tweed, 2016;Cook et al, 2016;Emmer, 2017). Formation or drainage of lakes can impact ecosystem dynamics by providing or removing a source of stored freshwater, altering the sediment flux within a basin, creating new habitat (e.g., Milner et al, 2008), or altering downstream flow characteristics (Tweed and Carrivick, 2015;Jacquet et al, 2017). Glacial lake outburst floods (GLOFs; when a lake dam suddenly fails or is breached; Clague and Evans, 2000) from icemarginal lakes can have massive impacts on downstream river channel morphology (e.g., Jacquet et al, 2017), disrupt ecosystems (e.g., Meerhoff et al, 2018), destroy infrastructure, and cause the loss of human lives (e.g., Carrivick and Tweed, 2016).…”

“…Formation or drainage of lakes can impact ecosystem dynamics by providing or removing a source of stored freshwater, altering the sediment flux within a basin, creating new habitat (e.g., Milner et al, 2008), or altering downstream flow characteristics (Tweed and Carrivick, 2015;Jacquet et al, 2017). Glacial lake outburst floods (GLOFs; when a lake dam suddenly fails or is breached; Clague and Evans, 2000) from icemarginal lakes can have massive impacts on downstream river channel morphology (e.g., Jacquet et al, 2017), disrupt ecosystems (e.g., Meerhoff et al, 2018), destroy infrastructure, and cause the loss of human lives (e.g., Carrivick and Tweed, 2016). Time-varying inventories of ice-marginal lakes are a critical first step in predicting future lake evolution and assessing GLOF hazards.…”