Regional variations in lake areas in China due to human and natural environmental factors since 1990

Abstract

Lakes indicate and regulate global environmental changes and regional climate. China’s highly uneven lake distribution and pronounced spatial variations in lake-area changes have remained unclear. The study aimed to understand the patterns and underlying drivers of lake-area changes in China over the past 34 years, focusing on regional variations influenced by climatic (temperature, precipitation, and climate water deficit), hydrological (runoff, snow water equivalent, palmer drought severity index, and soil moisture content), and human (farmland area, building area, fractional vegetation cover, population, gross value of industrial output, total output value of primary production, and gross domestic product) factors. The Google Earth Engine (GEE) platform and Landsat series remote sensing images were enlisted. Catering to regional variations in natural and cultural traits, five water indices extracted the areas of lakes and reservoirs larger than 50 km2 in China’s five major lake regions. Factor analysis and Mann-Kendall trend analysis identified relevant drivers. Mann-Kendall trend analysis explored the influence of factors on abrupt changes in lake area. Based on the correlation strength identified through factor analysis, factors weakly correlated with lake area were excluded, thereby reducing redundancy in the input for PLS-SEM. Finally, Partial Least Squares Structural Equation Modeling (PLS-SEM) quantitatively investigated the complex relationships and interactions among the potential factors. The results indicated differential extraction effectiveness of the five water indices for the lake regions. MNDWI effectively extracted lakes in the Qinghai-Tibet Plateau Lake Region (QTP_LR) and Northeast Plain and Mountain Lake Region (NPM_LR). NDWI, WI2019, and AWEI performed the best in the Eastern Plain Lake Region (EP_LR), Mong-Xin Plateau Lake Region (MXP_LR), and Yunnan-Guizhou Plateau Lake Region (YGP_LR), respectively. From 1990 to 2023, the trends in lake-area changes varied across regions. EP_LR shrank continually, whereas MXP_LR and QTP_LR expanded significantly. NPM_LR initially shrank and then expanded, whereas YGP_LR remained relatively stable. The responses of lake-area changes to drivers varied notably across regions, necessitating variable screening to reduce SEM model redundancy. The influence of natural (climatic and hydrological) and human factors on lake areas differed among regions. QTP_LR responded strongly to climatic factors, while other regions were more sensitive to human factors. The findings offered a theoretical foundation for lake management practices in different regions to facilitate the formulation of regional water use and conservation policies.