Characteristics and driving factors of lake level variations by climatic factors and groundwater level
2022
Asaṅga, | Wu, Xiong | Lu, Chuiyu | Sun, Qingyan | He, Xin | Yan, Lingjia | Qin, Tao
Hongjiannao Lake (HL), the largest desert freshwater lake in China, has been undergoing quickly evolution of lake area during the past 30 years. The causes and driving mechanism of such changes, however, are still not well understood. The evolution process can be divided into three phases: the stationary phase, the shrinking phase, and the rising phase, which were affected by climate change and human activities, such as unreasonable utilization and water diversion. Here, wavelet coherence was used to analyze the relationship between the groundwater level and the lake level, and the results shown that groundwater levels in the lakeshore region were positively correlated to lake level within a short lag period of approximately 30 days. Then a gradient boosting decision tree-based regression model was applied to analyze the relative importance of climatic factors (model 1) and both of climatic factors and groundwater level (model 2) to the lake level. In model 1, the most important factor was the evaporation to the HL level, while in model 2, it was the groundwater level and the evaporation, which also achieved better prediction performance. Finally, using the 2021 meteorological data and groundwater level, model 2 was utilized to dynamically predict the daily water level of the HL, showing that the lake level fluctuated upward.
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