Impacts of Permafrost Degradation on Hydrology and Vegetation in the Source Area of the Yellow River on Northeastern Qinghai-Tibet Plateau, Southwest China

Abstract

Under a persistent warming climate and increasing human activities, permafrost in the Source Area of the Yellow River (SAYR) has been degrading regionally, resulting in many eco-environmental problems. This paper reviews the changes in air temperature and precipitation over the past 60 years and presents the distribution and degradation of alpine permafrost in the SAYR. The review is focused on the permafrost degradation–induced changes in hydrology, wetlands, thermokarst lakes, ponds, and vegetation. Mean annual air temperatures have been rising at an average rate of 0.4°C/10a over the past 60 years, while precipitation has increased only slightly (16 mm/10a). Borehole temperature monitoring at the depth of 15 m shows the permafrost warming rates of 0.01–0.21°C/10a in the Headwater Aera of the Yellow River. As a result of permafrost thaw, the amount of surface waters has declined while groundwater storage has increased. Due to permafrost degradation, the supra-permafrost water table lowers gradually, resulting in a reduction in areal extents of wetlands and lakes in the SAYR. We further renamed the concept of the burial depth of the ecologically-safe supra-permafrost water table, the minimum depth of the groundwater table for sustaining the normal growth of alpine grassland vegetation, for the SAYR to describe the relationship between the lowering permafrost table and succeeding alpine vegetation. Furthermore, we recommended more studies focusing on snow cover and carbon stock and emissions related to permafrost degradation under a warming climate. We also advised to timely establish the long-term monitoring networks for the rapidly changing mountain cryosphere, alpine ecology, alpine hydrology, eco-hydrology, cryo-hydrogeology, and carbon fluxes. Moreover, process-based models should be developed and improved to better simulate and predict the responses of alpine ecosystem changes to the interacting cryospheric and other environmental variables and their ecological and ecohydrological impacts in the SAYR and downstream Yellow River basins. This study can help better manage the ecological and hydrological environments in the Upper Yellow River that are sensitive to changes in the alpine climate and cryosphere.

Quantifying the Contribution of Climate Change and Human Activities to Runoff Changes in the Source Region of the Yellow River

“…Climate change has also led to dramatic changes in the cryosphere, making hydrological processes more complex, with glacier retreat and permafrost degradation leading to a greater proportion of runoff recharge from snow and ice melt water and an earlier runoff peak [3,4,45]. Precipitation and temperature will increase in the future, evaporation will also be enhanced, and surface water resources may be reduced in the SRYR [16,43,46].…”

“…The economic and social development of China as well as ecological security are very important [15]. Average air temperature increased by 0.4°C×(10a) -1 during 1961-2020 [16], and precipitation slightly increased by 3.6 mm×(10a) -1 during 1960-2013 [17]. Climate change has also caused the SRYR to display continued permafrost degradation, with the area of permafrost declining from 2.4×10 4 km 2 in 1980 to 2.2×10 4 km 2 in 2016 [18] and demonstrating an accelerating trend after the 1990s [19,20].…”

Dynamic response and adaptation of grassland ecosystems in the Three-River Headwaters Region under changing environment: a review

“…From 1982 to 2014, the growing season temperature in the TRHR region showed the most significant upward trend in the northwest and southeast (Chen et al, 2020). Precipitation has increased slightly in the TRHR region in recent decades (Jin et al, 2022, Li et al, 2013a, Hu et al, 2022, Bai et al, 2020). The regional differences in precipitation increase are obvious.…”

“…Over the past 60 years, the TRHR has experienced significant warming, and the rate is higher than that of the global and overall Qinghai-Tibet Plateau (Bai et al, 2020, Jin et al, 2022, Hu et al, 2022, Li et al, 2013a, Bardgett et al, 2013. Warming varies by season and region (Liang et al, 2013).…”

“…The long-term effect of the deepening of the ecological groundwater level will promote the change of vegetation species and the regional evolution of plants. This in turn leads to the degradation and even desertification of alpine grasslands (Jin et al, 2022).…”