What drives the distinct evolution of the Aral Sea and Lake Balkhash? Insights from a novel CD-RF-FA method

Abstract

Study Region: The Aral Sea and Lake Balkhash. Study Focus: This study explores the impacts of climate change and human activities on the inflow of the Aral Sea and Lake Balkhash, revealing the different driving factors behind the evolution of inland lakes in arid environments. To achieve this, we propose a novel approach that combines classical seasonal decomposition with Random Forest and Factor Analysis (CD-RF-FA) to quantitatively assess the influences of climate change and human activities on lake inflow. New Hydrological Insights for the Region: During the period from 1960 to 1990, anthropogenic factors predominantly influenced the inflow to the lakes, contributing 89.9 %, 91.8 %, and 91.6 % to the Lake Balkhash Basin (BAK), the Syr Darya Basin (SYR), and the Amu Darya Basin (AMU), respectively. However, from 1991 to 2020, the influence of human activities diminished, and climate variables gradually dominated the changes in inflow, contributing 52.2 % and 47.2 % to BAK and SYR, respectively, with upstream inflow being the main driving factor. Additionally, reservoir construction and political factors also played significant roles in the variation of inflow, exerting direct or indirect effects. This study provides crucial insights into the complex interplay of factors affecting inland lakes in arid regions and informs strategies to mitigate the Aral Sea Syndrome.

Keywords

• Aral Sea
• Lake Balkhash
• Water balance
• Factorial analysis
• Random Forest