Area dynamics of alpine lakes in the Yamzhog Yumco Basin: Optimized water indices reveal spatiotemporal patterns and key drivers

• MBWI and MAWEI identified as lake-specific optimal indices via joint validation. • Lake changes concentrated near river inflows and hydrologically separated zones. • Isolated Puma Yum Co expanded climatically but anthropogenically-impacted lakes shrank. • Hydrological connectivity propagated anthropogenic impacts across the lake chain. • Lake shrinkage shifted from climate to anthropogenic to multi-factor control. Lake area dynamics on the Tibetan Plateau (TP) are critical for understanding ecological responses to global climate change. Employing 96 Landsat scenes from the Yamzhog Yumco Basin (1972–2023), this study evaluated seven water indices through a joint validation combining confusion matrices-based classification accuracy and linear regression-based areal consistency against manual visual interpretation (MVI) references. MBWI performed optimally in Puma Yum Co (PMYC), while MAWEI performed best for other four lakes (Overall accuracies >97 %, Kappa coefficients >0.93, R 2 = 0.665–0.991). Other indices misclassified ice, shallow turbid waters, and shoals, with NDWI, MNDWI, and EWI additionally producing substantial omission errors in some scenes. Yamzhog Yum Co (YZYC) experienced the most significant basin shrinkage (−15.56 km 2 /10a, R 2 = 0.709, p < 0.01), featuring shoreline retreat, separation from Kongmu Co (KMC), and interior island expansion. Climatic factors explained >86 % area variability pre-2005, whereas non-climatic factors (mainly pumped-storage operations) dominated during 2005–2015. Post-2016, precipitation re-emerged as the primary contributor (β = 0.519) for YZYC, although the model fit was statistically significant (R 2 = 0.598, p = 0.259), indicating combined anthropogenic-climate forcing. Connected lakes synchronized with YZYC, confirming connectivity-mediated anthropogenic propagation. Chen Co (CC) retreated along its western shore, while Bajiu Co (BJC) exhibited amplified fluctuations, potentially influenced by shallow morphology, seepage, and pastoral water use. KMC showed minimal change buffered by glacial melt and periodic water exchange. In contrast, PMYC, an isolated lake unaffected by anthropogenic infrastructure, expanded northwestward (2.24 km 2 /10a, R 2 = 0.634, p < 0.01), driven primarily by precipitation (β = 0.509, p < 0.05) consistent with the plateau-wide warming and wetting trend. This study demonstrates that intense anthropogenic activities can override and disrupt climate-driven hydrological regimes, providing critical insights for water resource management on the TP.