蒙古国中部草原地区风蚀沙漠化的风沙活动特征——以乔伊尔市为例

蒙古国是中蒙俄经济走廊的重要区段,但面临严重的荒漠化问题,区域经济社会发展受到严重威胁,而蒙古国中部草原地区是主要的荒漠化新扩展区,正经历强烈的草原风蚀沙漠化过程。以戈壁苏木贝尔省首府乔伊尔市为研究区,利用自建自动气象观测站（2019年5月—2020年7月）、集沙仪观测站（2019年8月—2020年8月）及当地气象站（1990—2018年）数据,对当地风蚀沙漠化的风动力条件、风沙流输沙及其他影响因素等基本特征进行了研究。结果表明：（1） 乔伊尔市具有强劲的风动力条件,年输沙势可达735.96 VU,合成输沙势为428.76 VU,合成输沙方向为SSW（195.06°）,风向变率指数为0.58,属高风能环境、中等变率双峰风况。（2） 临界起沙风速因受土壤水分和植被盖度的共同影响而随季节变化,夏季最高,冬季最低,春季与秋季居中,且相差较小。（3） 地表具有强烈的风沙活动,年风沙流输沙通量可达2.135 t·m^-1·a^-1,Owen最大输沙量模型适于该区风沙流模拟。研究结果对于蒙古国中部草原区防沙治沙和生态恢复具有重要参考价值。

Aeolian sand activity characteristics of wind erosion and desertification in the grassland area of central Mongolia:A case of Choir City

Desertification is known to be the “cancer of the earth”. Mongolia is a country with the most serious desertification in the world. The desertified land in Mongolia is still expanding, and the central region is an important new expansion area. The frequent dust storms have caused serious harm and are a great threat to infrastructure connectivity, energy and resource base construction, ecological security, and environmental health and have become a major hurdle limiting Mongolia’s socio-economic development and ecological security. Choir City, the capital of Gobi Sumber Province, is located in the central part of Mongolia. It is an important section of the Mongolian Plateau of the China-Mongolia-Russia economic corridor. It belongs to the mixed zone of grassland, dry grassland, and desert grassland. It is sensitive to natural and human disturbance and has serious wind erosion desertification. In this study, the wind dynamic conditions for the occurrence of local wind erosion desertification were examined using observations from the self-built automatic meteorological observatory (May 2019—July 2020) and the meteorological station of Choir City (1990—2018) and the sand collector (August 2019—August 2020). The results showed that (1) there were strong wind dynamic conditions for the occurrence of wind erosion desertification in the region. The annual sand drift potential was 735.96 VU, the resultant sand drift potential was 428.76 VU, and the resultant drift direction was SSW (195.06°). The wind direction variability index was 0.58, which belonged to the high wind energy environment with a moderate rate of variation-blunted double-peak wind conditions. (2) The critical wind speed was affected by soil moisture and vegetation coverage, which varied with seasons: it was the highest in summer and the lowest in winter, and spring and autumn are in the middle. (3) Because of the strong wind dynamic conditions and degraded surface, the sediment transport flux of aeolian sand flow was very high (2.135 t·m^-1·a^-1) in Choir City. The maximum sediment transport rate model developed by Owen was suitable for the simulation of aeolian sand flow in this area. This study presented a detailed analysis of wind dynamic conditions in Choir City, located in the central desert steppe region of Mongolia. The characteristics of critical starting winds in Choir City were analyzed in each season by combining soil moisture and particle size, vegetation conditions, and other factors to identify the wind dynamic basis and related influencing factors in the central steppe region of Mongolia and provide basic data for local wind and sand disaster control. The research results could provide an important reference for desertification control, ecological restoration, and local engineering construction in the desert steppe area of central Mongolia.