Spatiotemporal Dynamics Of The Lakes In The Lower Reaches Of Tarim River

"At a strategic view, water is most precious natural resources in arid lands, is the bloodline of Oasis". Lakes as part of the terrestrial water cycle, its role in the cycle in arid lands are particularly important. At present day, there are 108 lakes by area more than 1 km2 in Xinjiang Uyghur Autonomous Region, total area are 6236 km2, take 7.7% of the country’s total lake areas, and there are 98 lakes in arid land in Xinjiang, by area between 1 km2 to 10 km2.Tarim River basin is a unique in the world with its rich natural resources and fragile ecosystems, is a famous for its special geographical characteristics and environmental problems, can be considered in the study of water resources in the arid area representative. Since 1972 Dashkol reservoir was built, almost no water discharge to the lower reaches of Tarim River, causing to downstream ecological degradation, natural landscape has changed along with the drying riverbed. This situation continued almost 30 years, during this period Tetima Lake was dried up. Tarim River basin is an extremely arid area in Central Asia, in this region almost all natural processes or human activities are directly or indirectly effected by lackage of water resources, so the observation of the various forms of water resources is very important. Therefore, has become a study on environmental protection and ecological restoration in the lower reaches of the Tarim River became one of the hotspots, has aroused widespread concern in the community and Government. But currently researches mainly focused on the great lakes, such as Baghrash Lake and Lop Nur Lake..., the small lakes in desert area almost did not have been systematicly reaserched.Based on huge amount of multiple data, such as free of remote sensing data, and different era different scale of topographic maps, and the historical maps recorded and drawned by Western Explorers, combining image process software and GIS software, extract the lake waterbody information in lower reaches of Tarim River in different periods, by analyzing results, summarized following conclusions:1. According to Lake water area and change trends, tatal water area changes of the lakes in lower reaches of Tarim River can be divided to 3 time segments over the past 100 years: Before 60 s of 20 th century, hydrological conditions of Tarim River downstream better than recent years, human influences on hydrological process are very less, lakes are much more than now by number and area, total water area of the lakes are more than 2000 km2 in the end of 19 th century and beginning of 20 th century; from 60-70 s of 20 th century to end of 20 th century, following to constraction of water facilities in this region, human influences on hydrological process are increased, as an effecto of this water bodies are reduced or completely dried up in many lakes of this region, only few lakes left in Kanglayka region with its 30 km2 surfece water area; in this century, as an one of important result of Ecological Water Trancfusion Project held in Lower Reaches of Tarim River, hydrological conditions are improved, some lakes refilled with water those are dried up over the decades, total water area of the lakes in this region are reach to 760 km2 in 2013.2. The lakes of the Lower Reaches of Tarim River can be categorized into 3main types besed on lake basins: the lakes are distributed in west of state highway or west side of the mainstream are typical Eolic(wind-formed) Lakes; thoese lakes distributed in the east side of the mainstream or among the rivernet are Riverine(fluvial) Lakes; Tetima lake can be categoried as Tictonic Lake; there are some artificial lakes such as thoese 2 big reservoir.3. From analizing chende process of different lakes, summarized evolution status of Eolic Lakes in this region, and compared with Riverine Lakes in this region found that: Eolic Lakes and Riverine Lakes in this region very different by formaton time, by the shape, depth, water quality, etc.4. In moderd days effects of humen factors are more than natural factors on the lakes chenges of this region.From the research of spatio-temoral evolution of the lakes in the Lower Reaches of Tarim River based on multi-sources data some, some mothods founded worth to appliyed in small lake researches other aridlands: using multiple remote sensing data could be shortened monitoring intervals in small lakes in arid areas; materials recorded by Western explorers can provide valuable information for extending study time period; using the decision tree method with water index / vegetation index used as a parameter are simple, reliable, and efficient way for extracting information about simplified land cover types from remote sensing data.