A multi-temporal scale framework for comprehensive quantification and attribution of anthropogenic impacts on runoff.

Attribution analysis of runoff variation holds significant importance for water resource conservation and management. This study established a methodological framework for runoff reconstruction, quantification, and analysis of contribution rates. The framework comprises four core components: (1) Aggregation of hydro-meteorological variables across multiple time scales, thereby identifying the most representative temporal scale for a given river basin, effectively overcoming the limitation of single-scale approaches common in previous research. (2) Optimization of explanatory variables specific to each temporal scale by integrating Spearman correlation and variance inflation factor (VIF) analysis, effectively addressing multicollinearity issues often overlooked in previous studies. (3) Reconstruction of runoff using Random Forest Regression Model (RFRM) and Soil and Water Assessment Tool (SWAT), with multi-metric validation metrics, to ensure transferability across diverse river basins. (4) Across multiple temporal scales, the integration of remote sensing and statistical data to identify anthropogenic drivers addresses the limitations of single-factor attribution analysis. Tested in the Lan River Basin, the framework identified precipitation as the dominant meteorological driver (Spearman's p = 0.90 at the seasonal scale), determined monthly and bimonthly scales as optimal for modeling, and revealed the complementary strengths of RFRM and SWAT-the latter excelling particularly in simulating high-flow extremes. Integration of multi-source data further elucidated the dual role of human activities on runoff, underscoring the value of quantitative attribution. These findings offer methodological guidance for temporal scale and model selection while providing a transferable approach for runoff attribution.