Study region Qin River Basin, China. Study focus Understanding the evolution and attribution of ecohydrological processes under changing environments is critical for sustainable water management. This study establishes and applies a multi-component runoff validation framework for the Soil and Water Assessment Tool (SWAT) model to quantitatively dissect the impacts of a conceptual Returning Agricultural Land to River (RAR) initiative. New hydrological insights for the region Results revealed a distinct runoff component response hierarchy to the RAR initiative: surface runoff (SUR, 0.31–21.88%) > total runoff (TR, 0.42–12.90%) > baseflow (BF, 0.50–6.83%). This hierarchy highlights that ‘blue’ measures preferentially enhance fast flow pathways, contrasting with ‘green’ measures which often reduce overall yield. Key hydrological insights include a pronounced slope threshold effect (higher efficacy on slopes middle > upper basin), and marginal benefits of TR in the lower basin nearly tenfold those upstream. Spatially differentiated optimal implementation widths were identified (50 m, 50–100 m, and 100–200 m for upper, middle, and lower basins, respectively). These findings elucidate the unique runoff redistribution mechanisms and spatial heterogeneity induced by such "blue" initiatives, offering actionable insights for optimizing nature-based solutions in water-limited basins.
Cao et al. (Wed,) studied this question.