Abstract:

Objective: Taking Chahan Nur as a case study, this study aims to analyze the relative contributions of major meteorological factors to changes in the water surface area of inland terminal lakes in China. Method: Based on the lake surface area dynamics of Chahan Nur from 1984 to 2025 and the meteorological data in the same period, the trend testing, change-point analysis, and multivariate regression attribution were comprehensively applied to quantitatively identify the characteristics and driving mechanisms of lake area variation. Result: 1) From 1984 to 2025, the mean annual maximum lake surface area of Chahan Nur was 29.34 km². The lake area exhibited significant staged variation and could be divided into a relatively stable period from 1984 to 2004, a continuous shrinkage period from 2005 to 2023, and a rapid expansion period from 2024 to 2025. The mean lake surface areas during these three periods were 36.78 km², 18.16 km², and 57.35 km², respectively. The lake surface areas of Chahan Nur shrank to its minimum over the past 42 years in 2022, but in only three years, it expanded to its maximum over the past 42 years in 2025. 2) With the annual maximum lake surface area change (ΔArea) as the response variable, the meteorological-factor model, with the annual change in maximum lake surface area (ΔArea) as the response variable, explained approximately 43% of the interannual variation in water surface area, with precipitation identified as the dominant positive driver. The contribution of precipitation increased from 62.4% during 1984—2004 to 70.1% during 2005—2023, and further to 91.3% during the extreme-precipitation years of 2024—2025, indicating that the relative explanatory role of precipitation in interannual lake surface area variation gradually strengthened. Precipitation sensitivity analysis further showed a staged increase in the response intensity of lake surface area to precipitation. For every 100 mm increase in precipitation, the lake surface area increased by an average of 4.94 km², 6.00 km², and 9.09 km² during 1984—2004, 2005—2023, and 2005—2025, respectively. 3) From 1984 to 2025, vegetation coverage in the Chahan Nur Basin showed an overall fluctuating upward trend and was significantly positively correlated with both precipitation and lake surface area. 4) Residual decomposition indicated that the influence of factors beyond the major meteorological variables on lake area variation increased during 2005—2023. Conclusion: The shrinkage of the surface area of Chahan Nur from 1984 to 2025 is jointly influenced by natural and anthropogenic factors. Interannual variations in meteorological conditions alone cannot account for the full magnitude of the persistent decline in lake surface area. In conjunction with data on agricultural water use, irrigated land area, and groundwater depth, the results suggest that irrigation withdrawals, groundwater abstraction, and changes in hydrological connectivity may have played important roles, although their respective contributions require further quantitative assessment. Extreme precipitation can drive rapid short-term expansion of the lake surface, potentially creating a temporary window of opportunity for implementing basin-wide ecological restoration projects, including the Three-North Shelterbelt Program.

Key words: terminal inland lake, Chahan Nur, lake area dynamics, attribution analysis, the Great Green Wall