# Change and Driving Factor Analysis of Eco-Environment of Typical Lakes in Arid Areas
## 2 Materials and Methods  
### Overview of the Study Area  
The Tarim River basin in Xinjiang is the longest inland river in China [34]. It has experienced phenomena such as lake drying, widespread vegetation degradation, and aggravated land desertification, and the ecological environment is relatively poor. Taitema Lake, in the lower reaches of the Tarim River, is a typical representative of tail water lakes, which can maintain the ecological stability of the source water [35]. Taitema Lake is a huge ecological barrier located between the Quruq Desert and the Taklamakan Desert [36]. It has important ecological significance, and ecological water conveyance is crucial to maintaining the area and protecting ecological security in the arid tail water lake. Taitema Lake (\(39^{\circ}05^{\prime}\)-\(39^{\circ}45^{\prime}\) N and \(87^{\circ}20^{\prime}\)-\(88^{\circ}40^{\prime}\) E, with an average elevation of 807 m [37]) is located in the southeastern part of the Tarim basin in Xinjiang Uygur Autonomous Region, in the north of Ruoqiang County, 55 km away from the county seat (Figure 1). Lake Taitema has a warm, temperate, continental desert arid climate, with average annual precipitation of 28.5 mm, maximum annual precipitation of 118.0 mm, average annual evaporation of 2920.2 mm, and maximum annual evaporation of 3368.1 mm. The water sources of Lake Taitema are mainly the Tarim River and the Chechen River [38]. However, the formation of their water resources, water supply frequency, and flood frequency are significantly different. On the one hand, the Chechen River primarily originates from the Altun Mountains, which are in closer proximity to Taitema Lake. The river outflow mostly enters the lake area. On the other hand, the Tarim River mainly relies on melting ice and snowmelt from the West Tianshan Mountains and the Karakoram Mountains. Before 1921, for 1500 years, lake water flowed south into Lake Karakorum. In the past, the river water downstream of the Tarim River used to flow eastward into the Kongque River and eventually emptied into Lob Nor in Ruoqiang County. However, the course of the river water has changed, and it now flows southeast into Taitema Lake. According to the topographic map of aerial photographs taken by the National Mapping Bureau in 1959, Highway 218 divides Taitema Lake into two parts: the western part is supplied by the Cherchen River and has a slightly larger water area, while the eastern part is supplied by the Tarim River and has a slightly smaller water area [36]. However, excessive development and utilization of water and soil resources, especially the construction of Daxihazi Reservoir downstream of the river in 1972, directly led to the drying up of the Tarim River's and the Cherchen River's downward streams [37]. As a result, Taitema Lake, as the tail water lake of the Tarim River, significantly shrank and eventually dried up, causing serious ecological degradation in the region [35]. Before 1980, the center of Taitema Lake was about 20 km east of the Kuche-Ruoqiang highway. After it dried up, the lakebed was quickly buried by the desert and became flat land. In order to improve the increasingly severe ecological problems and water resource crisis in the region, ecological water conveyance has been implemented in the Tarm River basin since 2000 [38]. Since the implementation of ecological water conveyance, the center of Taitema Lake has moved to the west of the Kuche-Ruoqiang highway, about 30 to 40 km westward of the old site. This is because the ecological environment in this area was extremely poor, and the Quruq Desert in the northeast invaded southwest, raising sand and causing the Tarm River's ecological water to be unable to flow into the original lake and to be only able to move westward. More than 20 interventions of ecological water conveyance have been carried out in the lower reaches of the Tarm River from 2000 to 2020, and the water head can reach Taitema Lake.