绿洲演化与自然和人为因素的关系初探——以克里雅河下游地区为例

以位于塔里木盆地的克里雅河下游地区绿洲为例 ,论述了自然环境要素演变及人类活动对绿洲发育的重要作用。克里雅河下游地区的现代绿洲包括沿河岸分布的带状绿色走廊和河流终端干三角洲上的扇形牧业绿洲。依据对河流沉积物及古河道分析得出的结论是 ,在末次冰期晚期时 ,由于来自昆仑山的大量消融水的出现 ,克里雅河的绿色走廊横穿塔克拉玛干沙漠。类似的情况在距今约2 0 0 0年和小冰期时都出现过。这种大的变化是自然环境演变的结果。但是 ,近百年来特别是近 5 0年克里雅河下游牧业绿洲的严重退化是中游地区集中发展农业绿洲而增加引水量及下游地区过度砍伐所造成的。

THE RELATIONSHIP BETWEEN OASES EVOLUTION AND NATURAL AS WELL AS HUMAN FACTORS—— EVIDENCES FROM THE LOWER REACHES OF THE KERIYA RIVER, SOUTHERN XINJIANG, CHINA

Taking the oases in the lower reaches of the Keriya River as a demonstration case, the author has studied the dependence of the oases evolution on the natural environmental changes and human influences The present day oases of the lower reaches of the Keriya River consist of the green belt along the riverbed and the fan like oases at the end of the river course These kinds of oases are utilized as pasture Based on the fluvial deposits and older riverbed, the author concludes that the total runoff of the river was quite abundant during the late period of the last glaciation owing to the increase of melting water of the glaciers and snows Consequently, the River flowed through the Taklamakan Desert and reached the Tarim River of the northern fringe of the Tarim Basin Similar environmental conditions appeared 2000 a B P and during the little ice ages Such superlative variations were originated from natural environmental changes However, the especially serious deterioration of the pasture oases of the lower reaches of the river during the last hundred years, particularly since 1950s is caused by the intensive exploitation of the water for irrigation in the middle reaches The recent uncontrolled logging of the wood resources in the lower reaches has accelerated the degradation of the landscape considerably as well