Lake depth, a key parameter regulating evaporation in semi-arid regions: A case study from Dali Lake, China

As climate change intensifies, understanding the dynamics of lake evaporation is imperative, especially in semi-arid regions where water resources are already scarce. This study examines the regulatory role of lake depth on evaporation rates, focusing on a terminal lake in a semi-arid region: Dali Lake in China. Using the Complementary Relationship Lake Evaporation model, we simulated the heat and temperature lag time of Dali Lake, an 8 m deep lake, due to its heat storage capacity. This approach was validated through moderate-resolution imaging spectroradiometer (MODIS)-based surface temperatures of Dali Lake and adjacent Ganggenor Lake. Dali Lake, by storing heat during the warmer months, maintains lower surface temperatures compared with the shallower Ganggenor Lake. Under the same climatic conditions, Dali Lake has an annual evaporation of 980 mm, which is 45 mm less than that of Ganggenor Lake, which has an annual evaporation of 1024 mm. To further study the impact of lake depth, we simulated the heat storage and evaporation of Dali Lake during the Holocene, when the lake reached up to 34 m average depth, representative of the maximum depth reached by Dali Lake. During the Holocene, under constant climate conditions, the annual evaporation would be 44 mm/year less than the average evaporation from 1984 to 2016. Average annual evaporation decreased with increasing depth, showing a significant reduction during warmer months, while the release of heat during the ice-cover period did not result in additional evaporation. Our results highlight the important relationship between lake depth and evaporation under climate change, emphasizing the necessity for depth-specific water management strategies in semi-arid regions. During the lake shrinkage phase, by comparing the results of two evaporation models, we highlight the regulatory effect of heat storage in deeper bodies of water. The relationship between temperature and evaporation is complex and non-linear, and there is an increase in temperature that leads to an increase in evaporation rates, particularly during warmer months. As the depth increases, there is a clear decrease in average annual evaporation. image