Abstract: In recent years, the shrinkage of Dali Lake has caused serious ecological problems. To reveal the reasons for its shrinkage, the sedimentary core (DL-1) and the paleo-lake shoreline profile of Dali Lake were collected. Based on ²¹⁰Pb, ¹³⁷Cs, and optically stimulated luminescence (OSL) dating, the environmental evolution of Dali Lake Basin in the past 200 years was reconstructed by Mg/Ca and Ti. Further, combined with remote sensing, meteorological and socio-economic data of the basin over the past 40 years, the lakelevel changes were analyzed. The results showed that the area of Dali Lake had decreased by 44.35%, from 332.46 km² in 1768 to 185.0 km² in 2016. There was a cold and dry climate from 1800 to 1906, and then a warmwet and warmdry alternation. For more than 200 years, the change of rainfall intensity was consistent with the change of lake level, indicating that climate change was the main factor for lake shrinkage. Since 2009, there was a positive correlation between evaporation and lake level (P=0.01, R²=0.872), which was contradictory to the expectation that lake level shrinkage is caused by strong evaporation, indicating that human activities have a great influence on the lake level changes in this period.

Key words: sedimentary core, ancient shoreline, remote sensing data, lake area, Dali Lake.