J Arid Land (2013) 5(2): 188−198 doi: 10.1007/s40333-013-0156-0 jal.xjegi.com; www.springer.com/40333 Climate effects on an inland alpine lake in Xinjiang, China over the past 40 years HuiXia CHAI1, WeiMing CHENG1∗, ChengHu ZHOU1, ShangMin ZHAO2, HaiJiang LIU3 1 State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Re- sources Research, Chinese Academy of Sciences, Beijing 100101, China; 2 Department of Surveying Mapping, College of Mining Technology, Taiyuan University of Technology, Taiyuan 030024, China; 3 China National Environmental Monitoring Center, Beijing 100012, China Abstract: Inland lakes are important water resources in arid and semiarid regions. Understanding climate effects on these lakes is critical to accurately evaluate the dynamic changes of water resources. This study focused on the changes in Sayram Lake of Xinjiang, China, and addressed the effects of climate fluctuations on the inland lake based on long-term sequenced remote sensing images and meteorological data from the past 40 years. A geo- graphic information system (GIS) method was used to obtain the hypsometry of the basin area of Sayram Lake, and estimation methods for evaporation from rising temperature and water levels from increasing precipitation were proposed. Results showed that: (1) Areal values of Sayram Lake have increased over the past 40 years. (2) Both temperature and precipitation have increased with average increases of more than 1.8°C and 82 mm, respectively. Variation of the water levels in the lake was consistent with local climate changes, and the areal values show linear relationships with local temperature and precipitation data. (3) According to the hypsometry data of the basin area, the estimated lake water levels increased by 2.8 m, and the water volume increased by 12.9×108 m3 over the past 40 years. The increasing area of Sayram Lake correlated with local and regional climatic changes because it is hardly affected by human activities. Keywords: Sayram Lake; climate change; water body extraction; areal variation; inland alpine lake Citation: HuiXia CHAI, WeiMing CHENG, ChengHu ZHOU, ShangMin ZHAO, HaiJiang LIU. 2013. Climate effects on an inland alpine lake in Xinjiang, China over the past 40 years. Journal of Arid Land, 5(2): 188–198. Inland alpine lakes are a sensitive indicator of climate from lakes. An increasing number of studies (Fan and change (Guo et al., 2003). Changes occurring in these Li, 1984; Hu et al., 2002; Angel and Kunkel, 2010; lakes can reflect regional climate variations. Such Bai et al., 2011) indicated that many inland lakes in lakes are an important water resource in arid and arid and semiarid regions have decreased in surface semiarid regions (Fan and Li, 1984; Qin, 1999) and area since 1950. Bates et al. (2008) indicated that no the impacts of climate change on the water levels in globally consistent trend of lake water levels has been these lakes have delayed effects. Fluctuations in water found. Most lake levels in the basin regions of Qing- level significantly affect local climate. Consequently, hai (China), Australia, Africa (e.g. Zimbabwe, Zambia, it is necessary to study water level changes and exam- and Malawi), North America (e.g. North Dakota), and ine the evolution of these lakes and the effects on local Europe (e.g. central Italy) have decreased because of natural environments. the combined effects of drought, global warming and The clear understanding of inland lake variation human activities (Bates et al., 2008; Bai et al., 2011). under climate change is critical to accurately evaluate Indeed, many lakes (such as Ebinur Lake, Aydingkol water resources and to retrieve climate information Lake, and Lop Nur) in Xinjiang of China are shrink- ∗Corresponding author: WeiMing CHENG (E-mail: [email protected]) Received 2012-07-23; revised 2012-09-23; accepted 2012-10-04 © Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Science Press and Springer-Verlag Berlin Heidelberg 2013 HuiXia CHAI et al.: Climate effects on an inland alpine lake in Xinjiang, China over the past 40 years 189 ing and even drying up. In contrast, the water levels of Water Index (NDWI) based on a geographic informa- a small number of mountain lakes in Inner Mongolia, tion system (GIS) and remote sensing images, were Xinjiang, and the Qinghai-Tibet Plateau have risen used to extract water body information. because of increased snow and glacier melt. All these 1.1 Study area studies indicated that lakes undergo different proc- Sayram Lake, renowned as a “pearl” along the Silk esses and are affected by the local climate. In the Road, is the largest alpine lake and the highest cold Sayram Lake, which is located in the Tianshan Moun- water inland lake in Xinjiang Uygur autonomous re- tains (Xinjiang, China), the water level has slightly gion, China (Figs. 1a, b). It is situated between increased over the past 40 years. According to avail- 44°28′00″–44°46′00″N and 80°55′00″–81°25′00″E. able records, the lake area has been constantly grow- Sayram is 27 km in length from east to west, and 30 ing (Ma et al., 2003; Gao and Jia, 2005; Ding et al., km from north to south. It has an elevation of 2,073 m 2006; Hu, 2007; Bai et al., 2011). However, detailed asl. analysis of the lake variation and the quantitative ef- There are more than 20 small rivers supplied by al- fects of the local climate have not, to date, been pre- pine glacier and snow melt in the Sayram Lake basin, sented. and about 10 small villages where the local people are This study focused on the changes in Sayram Lake engaged in animal grazing for a living, and there is no using data from remote sensing images, and analyzed agriculture or industry. Thus, the basin suffers from trends and the relationship between areal values of the few human disturbances. There is only one national lake and meteorological data (precipitation and tem- road passing through on the southeast side of the lake perature) over the past 40 years. From our findings, (Ma et al., 2003). we can monitor local climate changes, because Say- The basin shows stratiform and circular geomor- ram Lake is little affected by human activities. phologic characteristics. From the lake center to 1 Data and methods mountaintops, geomorphologic units are in the fol- lowing sequence: the water body of the lake, lacus- The Sayram Lake region was selected as the study trine plain, alluvial-lacustrine plain, alluvial fan plain, area. Long-term sequenced Landsat Multi-spectral alluvial plain, alluvial-pluvial fan plain, alluvial-plu- Scanner (MSS), Thematic Mapper (TM)/Enhanced vial plain, fluvial hill, mid-altitude fluvial mountain, Thematic Mapper Plus (ETM+) images and meteoro- high-altitude periglacial mountain, and high-altitude logical data from four stations around the lake were glacial mountain (Yang, 2011). Generally, the south used. Three methods, supervised classification, sin- and east of the lake are steeper than the terrain in other gle-band threshold, and the Normalized Difference directions (Fig. 2). Fig. 1a Location of the study area Fig. 1b Topographic map of the study area 190 JOURNAL OF ARID LAND 2013 Vol. 5 No. 2 Fig. 2 Geomorphological map of the Sayram Lake area. Taken from Shuttle Radar Topography Mission digital elevation model (SRTM-DEM). Upper left: pseudocolor map of SRTM-DEM; Upper right: geological setting. Sayram was a fresh water lake before the late (Xinjiang Integrated Scientific Investigation Team of Pleistocene when its water could drain (Xinjiang In- the Chinese Academy of Sciences, 1966). As the water stitute of Geography, the Chinese Academy of Sci- of the lake is not easily utilized by humans, the lake is ences, 1986). However, it is now a salt water lake with little affected by human activities. The lake water closed-lake basin characteristics (Hu et al., 2002). level is relatively stable in summer (June, July and Geologically, the Sayram Lake basin is a graben August) and autumn (September, October and No- fault basin (Xinjiang Institute of Geography, the Chi- vember) (Ma et al., 2003). During the past 40 years, climate change has nese Academy of Sciences, 1986), located on the greatly influenced the lake (Shi and Zhang, 1995). It northern limb of the Bolehuoluo anticlinorium. It be- has affected the regional water cycle in the drainage longs to the Hercynian fold belt, indicating that Sayram basin, which is related to rainfall, evaporation, and is a fracture lake. The lake was formed in the Pliocene meltwater of glaciers and snow (Ma et al., 2003). or early Pleistocene (Ma et al., 2003). According to There are no hydrological or meteorological re- drilling data, Quaternary deposits, geologic and topog- cords for the Sayram Lake area, because of the lack of raphic maps (Xinjiang Institute of Geography, the Chi- large rivers in the study area (Ma et al., 2003). In the nese Academy of Sciences, 1986), the lake covered the study, we used the daily observed data from four me- largest area in the middle Pleistocene; after which its teorological stations (Wenquan, Alashankou, Jinghe area gradually decreased. and Yining) near Sayram Lake during the period 1970–2009 (Fig. 1a). The data comply with national 1.2 Data and province benchmarks. After analyzing meteoro- 1.2.1 Meteorological data logical data quality, some data were filtered out be- The water supply of Sayram Lake is from the melt cause they were deemed invalid or produced unrea- water of glaciers and snow, as well as from rainfall sonable temporal sequences. Daily temperature re- HuiXia CHAI et al.: Climate effects on an inland alpine lake in Xinjiang, China over the past 40 years 191 cords from Jinghe and Yining are continuous from that for other months.