Quantitative assessment of human activity on flow components based on information theory: a case study of the Weihe River basin

To investigate the nonlinear impacts of human activities on multi-source delayed flows, the Weihe River basin—an area subject to significant anthropogenic disturbances—was selected as the study area. The heterogeneity in responses of different delayed flows to human activities is systematically explored. A novel analytical framework was developed by integrating information theory with a multi-scale delay-flow separation approach, through which a Composite Anthropogenic Disturbance index was constructed to quantify human-induced impacts on delayed flows. Results showed that the influence of human activities on various delayed flows was closely related to the complexity of hydrological processes in the basin. In the upstream and midstream plain regions of the Weihe River, the influence across delayed flows was relatively uniform and less differentiated. However, in the Loess Plateau region, different delayed flows exhibited considerable disparities in their responses to human activities. Nighttime light, an economic development indicator, exhibited the strongest correlation with all delayed flows, reflecting that in the urbanizing Weihe River basin, increased economic activities exerted a significant influence on all delayed flows. This study enhanced the quantitative understanding of anthropogenic impacts on runoff and provided a methodological basis for water resource management under intensifying human interference.