半干旱区季节性河流在荒漠化发育中的作用——以内蒙古四子王旗塔布河流域为例

荒漠化发育方式和过程的各不相同 ,具有明显的地域性和成因差异性特点。半干旱区季节性河流在荒漠化地貌发育中的作用是引人注目的一个科学问题。内蒙古四子王旗塔布河流域内有丰富的第三系和第四系河湖相冲 (洪 )积沉积物。该流域正发生着内蒙古乌兰察布盟最严重的荒漠化。本文基于LandsatTM图像的处理与分析 ,对该区季节性河流流域的荒漠化程度、分布及其成因作了研究 ,探讨了风 -水复合作用下荒漠化发育的具体模式。在干旱 -半干旱的气候背景下 ,地表植被稀疏、甚至裸露 ,在暴雨作用下 ,形成的洪流搬运大量泥沙碎屑物质沉积在中下游的宽谷地带 ,随着河道的淤积、抬高与加宽 ,干燥的流沙向两岸蔓延 ;再在特殊地段河道的“狭管效应”与局部气流循环共同作用下 ,流沙向四周进一步扩展 ,与山前洪积扇相连 ,造成荒漠化大范围的发生和发展 ,并可能导致整个地区的荒漠化。

The role of seasonal river in the evolution of desertification in semi arid region: taking Tabu river basin of Inner Mongolia as an example

Desertification issue of farming pastoral interlaced area has been paid attention to by the whole society In different areas, the developing mode and process of desertification are quite different It is characterized by distinct regionality and differences in the cause of desertification. A noticeable scientific subject is the role of seasonal rivers in the evolution of desertified landforms in semi arid region Siziwang county located in the central part of Inner Mongolia and to the northwest of Ulanqab League lies between 110°20′～113°00′E and 41°10′～43°22′N It covers an area of 24016 km 2 , and topographically,it is higher in the southern part than in the northern Tabu river has many seasonal branches It is the longest river in Siziwang county In Tabu river basin, there are abundant outcrops of Tertiary and Quaternary fluvial lacustrine facies, and there are many sandbelts and ridges along the branch rivers At present, the most serious desertification process is in Ulanqab League of Inner Mongolia Taking Tabu river basin of Siziwang county as an example, and based on RS image processing and analyzing, the paper researches the role of seasonal rivers in the evolution of desertification in semi arid area, and analyzes idiographic mechanism and pattern of desertification development under combined action of wind water integration In arid and semi arid areas, especially when anthropogenic activities are involved, surface vegetation is sparse, and even barren ground is seen. Under the effect of rainstorms in summer, a great deal of mud and debris materials are transported by torrents, and these materials accumulated in the broad valleys of the middle and lower reaches of the rivers With the silting up of mud and sand, and the broadening of the river courses, driftsand is spreading to both banks In spring, with the co operation function of "the narrow tube effect of wind" and the partial circulation of air current, the sand spreads further around, and connects with the alluvial fans, resulting in the formation and development of large scale desertification. It eventually may lead to desertification in the whole area