中蒙俄经济走廊蒙古国段的风沙流特征

Characteristics of wind and sand flows in the Mongolian section of the China-Mongolia-Russia economic corridor

中蒙俄经济走廊穿越蒙古国主要生态类型区,本文对沿线的达尔汗、乔伊尔、赛因山达、扎门乌德4个观测区的风沙流进行研究,研究结果表明:(1)风沙流水平输沙量均随高度增加而降低,两者最优拟合函数随下垫面变化而不同,达尔汗和乔伊尔为指数函数,而赛因山达和扎门乌德为幂函数。(2)各观测区年输沙通量空间分异明显,其中乔伊尔最大,达尔汗其次,扎门乌德再次,赛因山达最小,这与传统认知有较大不同。(3)风沙流输沙通量空间差异与多种因素有关。乔伊尔处于海洋气流影响尾闾区,春季干旱发生频率高,正值风季,风速较大,风蚀强烈;其他地区春季干旱发生频率相对较低,其中达尔汗地处自然条件较好的北部河谷区,但由于农田开垦和过度放牧,风蚀较为强烈,而扎门乌德和赛因山达风季风速相对较小,且放牧强度较低,风蚀较轻。本文的研究结论对蒙古国因地制宜开展风沙灾害防治和荒漠化治理具有重要的参考价值。

Mongolia is the main route area of China-Mongolia-Russia economic corridor.Since 1990,the degradation of ecosystems has posed a severe challenge to Mongolia,especially the grasslands are seriously degraded,and the desertified grasslands reach one third of the total area of the country.Mongolia will have more economic construction activities in its desertified grassland area in the future,and wind and sand disaster control will be one of the major tasks.The China-Mongolia-Russia economic corridor crosses the main substratum ecotype landscape areas of Mongolia.In this paper,the wind erosion desertification area along the north-south longitudinal railroad in Mongolia is used as the target area for the study of wind and sand flow in four observation areas along the line,namely,Darkhan,Choir,Sayinshanda and Zamyn-Uud.Results show that:(1)The horizontal sand transport of wind and sand flow both decrease with increasing height,and the most suitable fitting functions for both vary with the subsurface,with Darkhan and Choir being exponential functions,while Sayinshanda and Zamyn-Uud are power function.(2)The spatial distribution of annual sand transport flux is not the same for each observation area,with the largest in Choir,followed by Darkhan,Zamyn-Uud,and the smallest in Sainshanda,which is different from the traditional perception.(3)The spatial distribution of sand transport fluxes from wind and sand streams is related to a variety of influencing factors.Choir has a high frequency of spring droughts because of the influence of the tail-end ocean currents,which coincides with the season of frequent strong winds,high wind speeds and severe wind erosion;other areas have relatively low frequency of spring droughts,among which,Darkhan is located in the northern valley area with better natural conditions,but wind erosion is stronger due to agricultural land reclamation and overgrazing,while in Zamyn-Uud and Sayinshanda,the winds in the windy season are relatively weak and the grazing intensity is low,so the wind erosion is light.The findings of this paper have important reference value for Mongolia to take targeted measures in wind and sand disaster and desertification control according to local conditions,and may also provide supporting evidence for the drastic changes of desertification.