MODIS-Derived Spatiotemporal Changes of Major Lake Surface Areas in Arid Xinjiang, China, 2000–2014

Abstract

Inland water bodies, which are critical freshwater resources for arid and semi-arid areas, are very sensitive to climate change and human disturbance. In this paper, we derived a time series of major lake surface areas across Xinjiang Uygur Autonomous Region (XUAR), China, based on an eight-day MODIS time series in 500 m resolution from 2000 to 2014. A classification approach based on water index and dynamic threshold selection was first developed to accommodate varied spectral features of water pixels at different temporal steps. The overall classification accuracy for a MODIS-derived water body is 97% compared to a water body derived using Landsat imagery. Then, monthly composites of water bodies were derived for the months of April, July, and September to identify seasonal patterns and inter-annual dynamics of 10 major lakes (>100 km 2 ) in XUAR. Our results indicate that the changing trends of surface area of major lakes varied across the region. The surface areas of the Ebinur and Bosten Lakes showed a significant shrinking trend. The Ulungur-Jili Lake remained relatively stable during the entire period. OPEN ACCESSWater 2015, 7 5732For mountain lakes, the Barkol Lake showed a decreasing trend in April and July, but the Sayram Lake showed a significant expanding trend in September. The four plateau lakes exhibited significant expanding trends in all three seasons except for Arkatag Lake in July. The shrinking of major lakes reflects severe anthropogenic impacts due to agricultural and industrial needs, in addition to the impact of climate change. The pattern of lake changes across the XUAR can provide insight into the impact of climate change and human activities on regional water resources in this arid and semi-arid region.

Monitoring dynamics and driving forces of lake changes in different seasons in Xinjiang using multi-source remote sensing

“…This caused a reduction in the lake area and water salinization. However, the impact of the built-up land on the lakes in Xinjiang was lower than that resulting from the climate (Li, Lu, et al, 2015). Therefore, the lake area showed a slight increasing trend.…”

“…We set A as 0.4 and C as 100 in our study according to Mo et al (2007). In addition, Li, Lu, et al, (2015) also set A as 0.4 and C as 100 to study lake change in Xinjiang. Because C and A can magnify CWI, which can made CWI positive value, and it is easy to analyze and compare.…”

“…A single threshold value derived for one image might not be suitable for another. Since there is no standard threshold for the whole study period, an optimized threshold must be identified for each scene or each month (Li, Lu, et al, 2015). In this study, we set a different threshold for each time step and extracted water pixels.…”

The Temporal and Spatial Variations in Lake Surface Areas in Xinjiang, China

“…Compared to traditional methods, remote sensing is less time-consuming, much more cost-effective, and has gained popularity in the study of lakes worldwide. For example, Bao [20]. However, most of these studies have focused either on a specific lake or on lakes in a specific region.…”

Water Resource Variability and Climate Change

“…Li et al [18] examine surface area fluctuations occurring in 10 major lakes in the arid province of Xinjiang, China, from 2000 to 2014 using MODIS time series imagery. The authors develop a classification method to accommodate varied spectral characteristics of water pixels and derived water bodies for April, July, and September in each year for 10 major lakes (>100 km 2 ) in the study area.…”