地理与地理信息科学

高原湖泊水体时空动态变化对区域生态安全至关重要。该文以青藏高原黄河源区扎陵湖和鄂陵湖为研究对象，首先，基于GEE集成1990—2024年多源遥感影像与气象数据，运用NDWI、MNDWI结合OTSU阈值法提取水体边界；其次，分析流域降水、气温、蒸散发量变化趋势及与湖泊面积的Pearson相关性，并利用CCM方法量化气象要素对湖泊面积的因果关系强度；最后，分析两湖岸线空间演变特征。结果表明：(1)扎陵湖和鄂陵湖面积变化历经收缩期（1990—2004年）、扩张期（2004—2010年）和稳定期（2010—2024年）3个阶段，面积谷值至峰值变化幅度分别为6.00%与12.48%；(2)空间上均呈现全域扩张态势，扎陵湖扩张集中在主湖区西、西北、东、东北方位以及东南相连的小湖区域，鄂陵湖则显著集中在西与西南方位；(3)两湖面积与降水量、蒸散发量、气温均呈显著正相关，CCM因果推断结果进一步证实三者对湖泊面积均存在正向驱动效应，其中降水占主导地位。该研究为揭示高原湖泊对气候变化的响应机制提供了更具机理性的科学依据。

The spatiotemporal evolution of water bodies in plateau lakes are critical to regional ecological security.This study takes Gyaring Lake and Ngoring Lake in the source region of the Yellow River on the Qinghai-Tibet Plateau as the research object.Firstly,based on the Google Earth Engine(GEE) platform,multi-source remote sensing imagery and meteorological data from 1990 to 2024 were integrated.The NDWI and MNDWI were combined with the OTSU threshold method to extract water boundaries.Secondly,trends in precipitation,temperature,and evapotranspiration within the basin were analyzed,along with their Pearson correlation with lake area.The convergent cross mapping(CCM) method was applied to quantify the causal strength of meteorological factors on lake area changes.Finally,the spatial evolution of the shorelines of both lakes was examined.It is found as follows.(1) The areas of Gyaring Lake and Ngoring Lake underwent three distinct phases:a contraction period(1990-2004),an expansion period(2004-2010),and a stabilization period(2010-2024),and the amplitude of change from minimum to maximum lake area was 6.00% and 12.48%,respectively.(2) Spatially,both lakes showed an overall expansion trend.Gyaring Lake expanded mainly in the west,northwest, east,and northeast of the main lake area,as well as in smaller connected lakes in the southeast.Ngoring Lake expanded notably in the west and southwest.(3) The areas of both lakes were significantly positively correlated with precipitation, evapotranspiration,and temperature.CCM-based causal inference further confirmed that all three factors have positive causal effects on lake area,with precipitation being the dominant driver.This study provides a more mechanistic scientific basis for understanding how plateau lakes respond to climate change.