Impact of spatial scale on the sensitivity of the water supply-demand balance to driving factors

Escalating water insecurity in the Yellow River Basin (northern/northwestern China) reflects a deepening structural disconnect between climate-driven water yield (WY) — shaped by steep precipitation gradients from the Tibetan Plateau across the Loess Plateau to the lower alluvial plains — and surging water consumption (WC) from irrigated agriculture, energy extraction, and accelerating urbanization. We develop an integrated water footprint accounting framework that couples GIS-based supply-demand mapping with Random Forest modelling and Geodetector–OLS spatial factor analysis to diagnose water stress at grid (∼1 km 2 ), municipal, and sub-basin scales over 2000–2024. WY is estimated through a calibrated water balance approach validated against the Yellow River Water Resources Bulletin; basin- and sub-basin-level comparisons confirm MAPE ≤5% across benchmark years. The water footprint decomposition distinguishes blue, green, and grey water components, enabling sector-specific demand attribution that conventional volumetric approaches obscure. Results reveal a widening upper-to-lower reach divergence: upstream sub-basins maintain relatively favorable supply ratios despite high interannual variability, while midstream Loess Plateau and downstream irrigation districts exhibit chronic blue water deficits ( R < 1) compounded by deteriorating grey water assimilation capacity. Random Forest importance rankings identify precipitation seasonality and land use transition as the dominant WY controls, while irrigated area expansion and industrial water intensity emerge as primary WC drivers. Geodetector interaction detection reveals that no single factor independently explains spatial stress patterns — rather, coupled socio-hydrological interactions, particularly between cropland extent and groundwater dependency, produce the most severe deficit zones. OLS residual analysis confirms spatially structured governance gaps unaccounted for by physical drivers alone. The framework identifies where deficits are structurally entrenched versus climatically induced, supporting differentiated policy responses: blue water efficiency mandates in irrigation districts, grey water regulation in industrial corridors, and ecological baseflow protection in upper-reach conservation zones. These findings advance multi-component water footprint diagnostics as a governance-relevant tool for basins under compounding hydro-ecological and socioeconomic stress. • Multi-scale framework quantifies water supply-demand dynamics in Haihe Basin. • Precipitation and topography control water yield, while GDP drives consumption. • Persistent water deficits in downstream and urban hotspots identified. • Framework guides effective water governance and ecological restoration.