Arctic terrestrial hydrology: A synthesis of processes, regional effects, and research challenges

Abstract

Terrestrial hydrology is central to the Arctic system and its freshwater circulation. Water transport and water constituents vary, however, across a very diverse geography. In this paper, which is a component of the Arctic Freshwater Synthesis, we review the central freshwater processes in the terrestrial Arctic drainage and how they function and change across seven hydrophysiographical regions (Arctic tundra, boreal plains, shield, mountains, grasslands, glaciers/ice caps, and wetlands). We also highlight links between terrestrial hydrology and other components of the Arctic freshwater system. In terms of key processes, snow cover extent and duration is generally decreasing on a pan-Arctic scale, but snow depth is likely to increase in the Arctic tundra. Evapotranspiration will likely increase overall, but as it is coupled to shifts in landscape characteristics, regional changes are uncertain and may vary over time. Streamflow will generally increase with increasing precipitation, but high and low flows may decrease in some regions. Continued permafrost thaw will trigger hydrological change in multiple ways, particularly through increasing connectivity between groundwater and surface water and changing water storage in lakes and soils, which will influence exchange of moisture with the atmosphere. Other effects of hydrological change include increased risks to infrastructure and water resource planning, ecosystem shifts, and growing flows of water, nutrients, sediment, and carbon to the ocean. Coordinated efforts in monitoring, modeling, and processing studies at various scales are required to improve the understanding of change, in particular at the interfaces between hydrology, atmosphere, ecology, resources, and oceans.

Methane distribution and oxidation around the Lena Delta in summer 2013

“…One is the hydrographic regime, which will experience a greater freshwater input and stronger stratification (Bring et al, 2016). The second is thawing of the permafrost, which will increase the fluxes of carbon and nutrients into the coastal Arctic region.…”

Recent climatic, cryospheric, and hydrological changes over the interior of western Canada: a review and synthesis

“…River discharge represents the spatially integrated response to inputs from rainfall, snowmelt, and glacier melt, and its character is influenced by internal watershed storage capacity, vegetation, soils, topography, and other landscape features affecting the delivery of water to the stream channel network. In cold regions, the response to input events is highly sensitive to antecedent conditions in the basin, including preconditioning of soils, snowpacks, surface and subsurface water storage, and surface drainage network connectivity (Spence and Woo, 2008;Carey et al, 2010;Bring et al, 2016), while the nature of response is also dependent on the character of precipitation and the storm type (e.g., Shook and Pomeroy, 2012). The timing, magnitude, duration, and other characteristics of discharge are therefore closely linked with climate and other Earth system components, and they are sensitive to their changes within the watershed over multiple timescales.…”

Size Distribution, Surface Coverage, Water, Carbon, and Metal Storage of Thermokarst Lakes in the Permafrost Zone of the Western Siberia Lowland

“…In particular, in the tundra, continuous permafrost development strongly influences water fluxes and storage, whereas in boreal plains, slow surface and subsurface water movement produces extensive wetlands [11]. Once the permafrost becomes discontinuous to sporadic in the south, this allows significant groundwater feeding of rivers [12] and, presumably, lakes [13].…”

“…The Arctic and subarctic permafrost-bearing regions exhibit the maximal changes in the terrestrial freshwater budget, although the hydrological responses to environmental changes strongly differ across the boreal and subarctic regions of the subarctic [11]. In particular, in the tundra, continuous permafrost development strongly influences water fluxes and storage, whereas in boreal plains, slow surface and subsurface water movement produces extensive wetlands [11].…”