Hydrological impacts of near‐surface soil warming on the Tibetan Plateau

Abstract

Climate warming can cause intense changes in regional soil freeze/thaw dynamics and thus exerts strong effects on hydrological processes. Because permafrost conditions vary widely across the Tibetan Plateau (TP), a better understanding the potential influences of permafrost types is helpful to project future hydrological changes.Using multilayer soil temperatures from 45 meteorological stations, this study investigated regional near-surface soil warming on the TP and related hydrological implications in two typical alpine basins. In cold and warm seasons, nearsurface soil temperature gradient (0-5 cm) showed significant increasing trends with average rates of 0.31 ± 0.13 and 0.19 ± 0.08 C per decade (p < 0.05), respectively. This implied increasingly more heat transferred downward from the ground surface annually, which also appeared in the deeper layer (5-10 cm) but was relatively weaker. Our results also reflected that increasing warming tended to cause higher baseflow (0.66 m 3 s −1 a −1 , p < 0.10) and quicker groundwater recession (−0.05 per decade, p < 0.05) in the permafrost-dominated (>60%) basin, but had much weaker hydrological effects in the low-permafrost (<20%) basin. The contrasting responses suggested similar hydrological impacts related to the fraction of permafrost coverage as in the circum-Arctic regions. Our study implies that the warming-induced weakening of freezing process has complicated hydrological impacts in the Tibetan basins dependent on the fraction of permafrost coverage. K E Y W O R D Shydrological regimes, near-surface soil warming, permafrost coverage fraction, Tibetan Plateau

Permafrost Hydrology of the Qinghai-Tibet Plateau: A Review of Processes and Modeling

“…Ye et al (2009) proposed the Q max /Q min ratio (maximum monthly runoff divided by minimum monthly runoff) as an indicator to quantify the impact of permafrost on hydrography recession. This index has been widely used in QTP permafrost hydrology analysis, including in the headwaters of the Yellow River (Wu P. et al, 2020) and across the QTP (Liu et al, 2020;Song et al, 2020). These researchers found that there was a significant positive relationship between the Q max /Q min ratio and basin permafrost coverage.…”

Developing a Physics‐Informed Deep Learning Model to Simulate Runoff Response to Climate Change in Alpine Catchments

“…The elevation of the SRYR ranges from 2,656 m to 6,252 m, making it an amplifier of global climate change—the annual mean air temperature in this region has increased at the rate of 0.33°C per decade since 1960, which is almost twice as fast as the global temperature warming. The rapid temperature increase accelerates the degradation of the cryosphere in the SRYR, as evidenced by a decrease in the maximum thickness of seasonal permafrost of 0.012 m per year and a decline in the area ratio of permafrost of 1.1% per year during 1981–2015 (Qin et al., 2017), shorter snow accumulation periods and days of snow cover from 1978 to 2016 (X. Liu, Zhang, et al., 2020), and a glacier area shrank from 125 km 2 in 1960 to 104 km 2 in 2000 (J. Yang et al., 2003). Thus, the study on the runoff response under climate change in the SRYR is also of great reference significance for other alpine mountains.…”

“…Given that a large number of studies have shown that the impacts of the soil freeze‐thaw process on runoff can be mainly reflected in the hydrography recession (Gao et al., 2021), the Q max / Q min ratio (Ye et al., 2009) and the discontinuous baseflow recession phenomenon (DBR) (Gao et al., 2022) were selected to evaluate the performance of the model in simulating the impacts of soil freeze‐thaw on runoff from different aspects. The Q max / Q min ratio, initially defined as the ratio of maximum monthly runoff to minimum monthly runoff and later expanded to include the ratio of summer rainfall flow to winter baseflow when applied in the SRYR (P. Wu, Liang, et al., 2020), was widely used to quantify the impact of permafrost degradation on runoff (Gao et al., 2021; L. Liu, Zhang, et al., 2020). The Q max / Q min ratio is mainly based on the understanding that permafrost degradation increases soil infiltration and percolation during the thawing summer season, enhancing groundwater storage, which in turn leads to the decline of summer rainfall flow and the rise of winter baseflow (A.…”

“…Zhou et al, 2014), SWAT (Gu et al, 2022;K. Li, Wang, et al, 2021;Zeng et al, 2022), VIC(S. Li, Wang, et al, 2021;Y. Wang, Zhang, et al, 2020), Alpine3D (Brauchli et al, 2017), GBEHM (B.…”

Impact of Fully Coupled Hydrology-Atmosphere Processes on Atmosphere Conditions: Investigating the Performance of the WRF-Hydro Model in the Three River Source Region on the Tibetan Plateau, China

“…During 1956-2012, the annual runoff in LRB and YARB increased, while YRB slightly decreased [53]. Under the impact of climate change, frozen ground degradation increased the groundwater discharge rate in winter [54]. Direct snowmelt runoff coefficients are mainly controlled by the air temperature freezing index [55].…”