Hydrothermal variation and its influence on the desertified ground surface of Qinghai-Tibet Plateau

Blown sand activities in Qinghai-Tibet Plateau are strong and desertified lands are widely distributed. Variation of hydrothermal conditions after ground surface desertifies in permafrost regions currently remains unclear. The variations of water content and thermal flux of the desertified ground surface were thus investigated by synchronization contrast observation of the locale field. Results show that water content decreased after the ground surface of Qinghai-Tibet Plateau desertified, especially at the surface depth of 0.05 m. The annual average water content decreased by nearly half. As the soil of desertified ground surface became coarse, water storage and water retention capacities simultaneously weakened. With the high permeability coefficient, the water holding capacity and thermal conductivity of sand layer decreased, thus causing the decrease of thermal flux on the sand layer. The heat conducted through the sand layer to the underground decreased, which can prevent the permafrost from warming and thawing and is therefore beneficial to delaying permafrost degradation.