Water System Changes Of The Middle Reaches Of Tarim River In Recent 50 Years And Its Response On Ecological Environment

Water is a key factor of sustainable development of the oases and basis of maintaining the ecological environment. Tarim River is a dissipative inner river whose middle reach is characterized by very arid climate, and rare precipitation. The middle reach of Tarim River is the largest consumptive area in the whole river and its water system is very complicated. Tarim River is a wandering river whose watercourse is frequently changed by natural and human factors. The improvement of the ecological environment of the desert which is the peripheral layer of the oasis and the acceleration of the oasis economy in the middle and lower reach depend upon the sound distribution and efficient utilization of the water resource, which is the guaranty of the sustainable development of ecological environment in the oasis and desert. So the research on the change of the river system, especially the change procedure of the middle and lower reach, and sound utilization of the water resource become an important issue, which plays a significant role in protecting the Tarim Populus Euphratica Nature reserve and the ecological environment of the lower reach and maintaining the healthy development of the whole drainage area of Tarim River.The relief map of 1958, 1972 and the remotely sensed imaginary of ETM2000 were analyzed by RS and GIS tools to get the data of the river system in study area. According to these data the change procedure of the river system in recent 50 years and its characteristics were obtained. Oaman River was chosen as a target area due to its obvious river system change. The landscape pattern in time series and its evolvement of Osman river were analyzed according to the landscape theory and some index like patch shape, isolation index, diversity index and evenness index.The result shows that there are some changes in ecological environment in recent 30 years since Osman River formed. The desert area gradually decreased with the decline of dominance in the landscape. The nondense woods area increased and became a dominate landscape in 80's year by occupying the 40% of the whole area.The landscape pattern change of the nondense woods is the basic of the change of landscape pattern in whole area. Beside that, the role of the woods shows the tendency of increase. This once again shows that changes in the allocation of water resources is the most affected factor in the evolution of the ecological environment in arid areas.