新疆库尔勒及其毗邻地区绿洲的形成演变

FORMATION AND EVOLUTION OF THE OASES OF KORLA AND ITS WICINITIES, XINGJIANG

库尔勒及其毗邻地区绿洲为新疆典型绿洲之一。楼兰毁灭、罗布泊及台特马湖干涸、“绿色走廊”缩短变窄、库尔勒发展为新疆第二大城市等展现了该绿洲兴衰演变过程。通过论述库尔勒及其毗邻地区绿洲形成与特征 ,分析了绿洲演变阶段、原因和过程 ,预测绿洲演变趋势。

The Oases of Korla and its vicinities, Xinjiang, are characterized by the unique natural conditions and the intensive and frequent human activities. Oasis evolution, such as destruction of Loulan, drying-up evolution of Lop Nur Lake and Taitema Lake, shortening and narrowing of the river-side forest corrider, enlargemgment of Korla City and the area under cultivation in the reclamation areas, is paid a great attention to all along. Since A.D.400, the oasis over Korla and its vicinities have undergone 3 main stages, i.e., the flourishing stage before A.D.500, the stage of temporal and spatial change of the oasis caused by change of the river courses during the period from A.D.500 to the 1950s, and the reducing stage of the oasis caused by artifical factors since the 1950s. Evolution of the oasis is related to the natural factors, such as geologic and geomorphologic forces, climate warming and drying, change of the river courses, sand drift disasters, and also influenced by artificial factors, such as population growth, severe deforestation of popular diversifolia and Tamarix chinensis, reclamation, artificial control of water sources. Evolution processes of the oasis mainly include: (1)Along with reduction of the streamflow from Kongqi River and Tarim River to the lakes, Lop Nur Lake, Taitema Lake, etc., evolved in a sequence of shrinkage of the lakes → dried-up → salt crust → wind-erosion land or sand land and sand-dune land, and the plants withered in the areas around the lakes; (2)Temporal and spatial change of the oasis is caused by change of the river courses in evolution of desert → oasis or oasis → desert; (3)Evolution of lowering of groundwater level → withering of plants → land desertification → sand dunes. It is caused by damming of Kongqi River and Tarim River; (4)Oases of Tikanlik reclamation area evolves in a seqence of Popular diversifllia and Tamarix chinensis land or grassland → cultivated land or abandoned cultivated land → desert or salinized land; (5) Water and land exploitation and urban constrution make the natural oases evolve towards the artificial one, and the oasis at the lower reaches and river tails evolves towards desert. Thus, the paper proposes to plan the water consumption in the watersheds, increase the water consumption for the ecology, increase the water sources and reduce the water consumption, regulate the structure of planting, exploit and utilize the solar and wind energy resources, and protect the desert vegetation, which is the only way to maintain the stability of the oases, control land desentification of the oases, and ensure the unblocking of National No.218 highway and regional sustainable development.