Hydrologic Impacts of Thawing Permafrost—A Review

Abstract

Where present, permafrost exerts a primary control on water fluxes, flowpaths, and distribution. Climate warming and related drivers of soil thermal change are expected to modify the distribution of permafrost, leading to changing hydrologic conditions, including alterations in soil moisture, connectivity of inland waters, streamflow seasonality, and the partitioning of water stored above and below ground. The field of permafrost hydrology is undergoing rapid advancement with respect to multiscale observations, subsurface characterization, modeling, and integration with other disciplines. However, gaining predictive capability of the many interrelated consequences of climate change is a persistent challenge due to several factors. Observations of hydrologic change have been causally linked to permafrost thaw, but applications of process-based models needed to support and enhance the transferability of empirical linkages have often been restricted to generalized representations. Limitations stem from inadequate baseline permafrost and unfrozen hydrogeologic characterization, lack of historical data, and simplifications in structure and process representation needed to counter the high computational demands of cryohydrogeologic simulations. Further, due in part to the large degree of subsurface heterogeneity of permafrost landscapes and the nonuniformity in thaw patterns and rates, associations between various modes of permafrost thaw and hydrologic change are not readily scalable; even trajectories of change can differ. This review highlights promising advances in characterization and modeling of permafrost regions and presents ongoing research challenges toward projecting hydrologic and ecologic consequences of permafrost thaw at time and spatial scales that are useful to managers and researchers.Abbreviations: AEM, airborne electromagnetic; ALT, active layer thickness; CALM, Circumpolar Active Layer Monitoring; EMI, electromagnetic induction; ERT, electrical resistivity tomography; GPR, ground-penetrating radar; InSAR, Interferometric Synthetic Aperture Radar; NMR, nuclear magnetic resonance; SR, seismic refraction; TDEM, timedomain electromagnetics.Permafrost hydrology is a rapidly progressing research field, and a number of new discoveries and questions have emerged in recent years. Research interest in cold regions has been spurred in part by surface temperature warming rates in high latitudes (McBean et al., 2005) and high altitudes (Pepin et al., 2015) that are greater than the global average. This warming has produced changes to the cryosphere, including permafrost (ground that is £0°C year round), that impact hydrologic processes and conditions (ACIA, 2005;Hinzman et al., 2013). Despite increased attention, there are still critical limitations in hydrologic data coverage, subsurface characterization, process-level understanding, and integrated modeling approaches. Due to its low hydraulic conductivity (K), permafrost strongly affects the movement, storage, and exchange of surface and subsurface water. In...

Increasing Winter Baseflow in Response to Permafrost Thaw and Precipitation Regime Shifts in Northeastern China

“…Thus, the positive trends in winter baseflow indicate increased winter groundwater discharge, which likely was caused by enhanced groundwater recharge and groundwater storage due to ground thaw [23]. In general, permafrost thaw is expected to increase surface and subsurface hydrologic connectivity of watersheds and thereby lead to enhanced interactions between surface water bodies and aquifers [66]. It should be noted that the analyses presented herein do not disentangle the hydrologic changes due to permafrost thaw from those caused by seasonal frost changes, and the latter warrants further investigation.…”

“…These differences likely arise because (1) the watersheds in the present study span discontinuous, sporadic, and isolated permafrost systems that are more sensitive to climate warming than continuous permafrost environments [6,66] and (2) [68] and in Alaska (with the highest increases in winter in the interior region of 0.22 • C·decade −1 from 1949 to 1998) [69]. The spatial distribution of our results also points to the importance of permafrost thaw as a driver of hydrologic change.…”

Change in frozen soils and its effect on regional hydrology, upper Heihe basin, northeastern Qinghai–Tibetan Plateau

“…Changes in frozen soils can greatly affect land-atmosphere interactions and the energy and water balances of the land surface (Subin et al, 2013;Schuur et al, 2015), altering soil moisture, water flow pathways, and stream flow regimes (Walvoord and Kurylyk, 2016). Understanding the changes in frozen soils and their impacts on regional hydrology is important for water resources management and ecosystem protection in cold regions.…”

Estimating interaction between surface water and groundwater in a permafrost region using heat tracing methods

“…Significant hydrological changes in permafrost regions have received worldwide attention because water resources and ecosystems are particularly vulnerable to climate change (Bense et al, 2012;Woo, 2012;Walvoord and Kurylyk, 2016). Due to its hydrogeological function as an aquitard, permafrost impacts the movement, storage, and exchange of surface water (SW) and 5 groundwater (GW).…”

“…Although explanations of the linkage between permafrost thaw and hydrological processes abound, the logistical challenges of measuring and monitoring subsurface water fluxes and storage in permafrost regions limits the predictions of how future climate change may influence hydrological conditions in these regions (Walvoord et al, 2012;Walvoord and Kurylyk, 2016). Furthermore, existing modeling studies of increases in baseflow and sub-permafrost flow are based on hypothetical scenarios (Ge et al, 2011;Bense et al, 2012).…”