【摘要】 <正>沙漠地区水系和湖泊的演变,有很多历史事实可以证明。由于河流与湖泊的变迁而引起绿洲转移和城廓荒废,也是常见的现象。关于塔里木河下游罗布泊以及黑河下游居延海交替变迁的报道,曾轰动了全世界的地理学界。至于石羊河下游民勤绿洲的水系演更多还原

【Abstract】 <ABSTRACT>The Minchin Oasis is one of the typical desert oases of China. Its area has ex-perienced some expansion in spite of the decrease of the river discharge and the shrink-age of the lake surface. The evolution of the drainage system of the oasis can be divided into three periods (the period of natural drainage, the period of semi-natural drainage, and the period of artificial drainage) and six stages (the Chung-Tuan Lake stage, the Chu-ye Marsh stage, the Tu-ye Marsh stage, the Pai-Ting Lake stage, the Tsing-Tu Lake stage, and the Leap-forward Irrigation Channel stage). Throughout all these periods and stages the volume of water of the rivers and lakes was on the decrease, and the natural drainage system was finally replaced by the artificial drainage system-----------reser-voirs and irrigation channels. The decrease of the river discharge was not caused by the desication of the climate but by the destruction of natural vegetation cover and the diversion of the water for irrigation in the upper courses of the rivers. After the libera-tion, the project of land reclaimation and water conservation in large scale carried on in the arid regions of the Northwest has opened a new era for the Minchin Oasis.更多还原