Landsat observations reveal increasing trend in lake clarity on the Qinghai-Tibetan Plateau: Insights into the lake optical response to climate change

Citation

Wang S, Zhang W, Tan Z, Spyrakos E, Shi K, Somasundaram D, Wu Z, Zhang F, Li J & Zhang B (2026) Landsat observations reveal increasing trend in lake clarity on the Qinghai-Tibetan Plateau: Insights into the lake optical response to climate change. Remote Sensing of Environment, 340, Art. No.: 115424. https://doi.org/10.1016/j.rse.2026.115424

Abstract
Lakes across the Qinghai-Tibetan Plateau (TP) have undergone substantial environmental changes in recent decades, under the influence of climate warming and enhanced precipitation. But the long-term changes in lake optical properties and their responses to climate change on the TP remain less explored. This study utilizes Landsat series datasets from 1986 to 2024 to estimate a fundamental lake optical property—the Secchi disk depth (ZSD) in TP lakes, for tracking the long-term shifts in TP lake ecosystems. To accommodate the limited spectral information of Landsat 5/TM imagery, an improved semi-analytical QAARGB model was proposed to enhance the applicability of the semi-analytical model on lakes with relatively low ZSD (<1 m). To maintain the consistency of ZSD retrieval across Landsat series datasets, MODIS data were also employed for cross-calibration. The results unveil a noteworthy upward trend of ZSD across TP lakes over the nearly 40 years (with average Sen's slope of 0.019 m/yr, P < 0.05), with more pronounced improvements observed in the western and central TP regions. Analysis of long-term lake ZSD and meteorological factors revealed three distinct response patterns of lake ZSD to climate change on the TP. These patterns were predominantly associated with NDVI (33.0% of lakes), lake area (31.0%), and air temperature (4.9%), unveiling clear spatial heterogeneity in the dominant meteorological factors associated with interannual ZSD variations. These findings highlight the cascading impacts of climate change on TP lakes—mediated by hydrological expansion, watershed vegetation, and thermal regime—ultimately reshaping their optical and ecological characteristics.

Keywords
Secchi disk depth; Qinghai-Tibetan Plateau lakes; Landsat; Climate change

Journal
Remote Sensing of Environment: Volume 340