Links between seasonal suprapermafrost groundwater, the hydrothermal change of the active layer, and river runoff in alpine permafrost watersheds

. The seasonal dynamic of suprapermafrost groundwater significantly affects runoff generation and concentration in permafrost basins and is a leading issue that must urgently be addressed in hydrological research in cold and alpine regions. In this study, the seasonal dynamic process of the suprapermafrost groundwater level (SGL), vertical gradient changes of soil temperature (ST) and moisture content in the active layer (AL), and river level changes were systematically analyzed at four 15 permafrost watersheds in the Qinghai–Tibet Plateau using comparative analysis and the nonlinear correlation evaluation method. How freeze–thaw processes impact seasonal SGL, and the links between SGL and surface runoff, were also discussed. The SGL process in a hydrological year can be divided into four periods: (A) a rapid falling period (October– middle November), (B) a stable low-water period (late November–May), (C) a rapid rising period (approximately June), and (D) a stable high-water period (July–September), which synchronously respond to seasonal variations in soil moisture and 20 temperature in the AL. The characteristics and causes of SGL changes varied significantly during the four different periods. The freeze-thaw process of the AL has crucial regulatory effects on SGL and surface runoff in permafrost watersheds. During Period A, with rapid AL freezing, the ST had a dominant impact on the SGL. In Period B, the AL was entirely frozen because of the stably low ST, and the SGL dropped to the lowest level with small changes. During Period C, ST in the deep soil layers of the active layer (below 50 cm depth) significantly impacted the SGL (nonlinear correlation coefficient R 2 >0.74, 25 P<0.05), whereas the SGL change in the shallow soil layer (0–50 cm depth) had a closer relationship with soil moisture content. Rainfall was the major cause for the stable high SGL during Period D. In addition, the SGLs in Periods C and D were closely linked to the retreat and flood processes of river runoff. The SWL contributed approximately 57.0–65.8 % of the river runoff changes in Period D. These findings can provide references for hydrological research in permafrost basins and guide the rational development and utilization of water resources in cold and alpine regions.

[1]  T. Han,et al.  The hydrothermal changes of permafrost active layer and their impact on summer rainfall-runoff processes in an alpine meadow watershed, Northwest China , 2023, Research in Cold and Arid Regions.

[2]  Y. Sjöberg,et al.  Sensitivity of headwater streamflow to thawing permafrost and vegetation change in a warming Arctic , 2022, Environmental Research Letters.

[3]  Z. Wen,et al.  Impact process and mechanism of summertime rainfall on thermal-moisture regime of active layer in permafrost regions of central Qinghai-Tibet Plateau. , 2021, The Science of the total environment.

[4]  B. Gartsman,et al.  Spatial and Temporal Dynamics of Sources and Water Regime of the Ugol’naya-Dionisiya River (Anadyr Lowland, Chukotka) , 2021, Water Resources.

[5]  Wu Jichun,et al.  Soil hydrological process and migration mode influenced by the freeze-thaw process in the activity layer of permafrost regions in Qinghai-Tibet Plateau , 2021 .

[6]  Zeyong Gao,et al.  Suprapermafrost groundwater flow and exchange around a thermokarst lake on the Qinghai–Tibet Plateau, China , 2020 .

[7]  O. Pokrovsky,et al.  Spatial and Seasonal Variations of C, Nutrient, and Metal Concentration in Thermokarst Lakes of Western Siberia Across a Permafrost Gradient , 2020, Water.

[8]  F. Ling,et al.  Recent advances (2010–2019) in the study of taliks , 2020, Permafrost and Periglacial Processes.

[9]  Genxu Wang,et al.  The impact of land surface temperatures on suprapermafrost groundwater on the central Qinghai‐Tibet Plateau , 2019, Hydrological Processes.

[10]  G. Kling,et al.  Active Layer Groundwater Flow: The Interrelated Effects of Stratigraphy, Thaw, and Topography , 2019, Water Resources Research.

[11]  O. Pokrovsky,et al.  Permafrost thaw and climate warming may decrease the CO2, carbon, and metal concentration in peat soil waters of the Western Siberia Lowland. , 2018, The Science of the total environment.

[12]  J. Seibert,et al.  Pre-event water contributions to runoff events of different magnitude in pre-alpine headwaters , 2017 .

[13]  S. Wullschleger,et al.  Active layer hydrology in an arctic tundra ecosystem: quantifying water sources and cycling using water stable isotopes , 2016 .

[14]  Joshua C. Koch,et al.  Lateral and subsurface flows impact arctic coastal plain lake water budgets , 2016 .

[15]  O. Pokrovsky,et al.  Magnesium isotopes in permafrost-dominated Central Siberian larch forest watersheds , 2014 .

[16]  Georgia Destouni,et al.  Exchange and pathways of deep and shallow groundwater in different climate and permafrost conditions using the Forsmark site, Sweden, as an example catchment , 2013, Hydrogeology Journal.

[17]  Andrew Frampton,et al.  Using streamflow characteristics to explore permafrost thawing in northern Swedish catchments , 2013, Hydrogeology Journal.

[18]  Clifford I. Voss,et al.  Impacts of climate, lake size, and supra- and sub-permafrost groundwater flow on lake-talik evolution, Yukon Flats, Alaska (USA) , 2013, Hydrogeology Journal.

[19]  Li Chunjie,et al.  The variability of soil thermal and hydrological dynamics with vegetation cover in a permafrost region , 2012 .

[20]  Edward A. G. Schuur,et al.  Climate change: High risk of permafrost thaw , 2011, Nature.

[21]  Qingbai Wu,et al.  Exchange of groundwater and surface‐water mediated by permafrost response to seasonal and long term air temperature variation , 2011 .

[22]  Victor F. Bense,et al.  Evolution of shallow groundwater flow systems in areas of degrading permafrost , 2009 .

[23]  I. Clark,et al.  Groundwater Contributions to Discharge in a Permafrost Setting, Big Fish River, N.W.T., Canada , 2001 .

[24]  M. Woo,et al.  Hydrological Response of a Patchy High Arctic Wetland , 2000 .

[25]  L. Lebedeva.  Tracing surface and ground water with stable isotopes in a small permafrost research catchment , 2019, E3S Web of Conferences.

[26]  Yao Yong-xi.  Summarization on Monitoring Methods & Instrument for Underground Water , 2010 .

[27]  Cao Wen.  A study of the geological environmental of suprapermafrost water in the headwater area of the Yellow River , 2003 .

[28]  Ming-ko Woo,et al.  Suprapermafrost groundwater seepage in gravelly terrain, resolute, NWT, Canada , 1995 .