Divergent patterns of anthropogenic pressures on reach-scale rivers across China under future scenarios

Anthropogenic pressures from irrigation and human usage (i.e. domestic and industrial use) pose growing challenges to river sustainability under future global change. However, how these pressures evolve across river networks at fine spatial scales remains poorly understood. Here we project the anthropogenic pressures on 129 429 river reaches in China from 2020 to 2050 under the four CMIP6 scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), using a proximity-based index that integrates built-up and irrigated areas. The results show that the river reaches in the Hai and Huai River basins (RBs) are projected to face high and intensifying anthropogenic pressures, which are further exacerbated by meteorological drought threats under the SSP1-2.6 and SSP2-4.5 scenarios. In contrast, the Southwest and Inland RBs exhibit approximately 5% of the anthropogenic pressures observed in the Huai RB, but meteorological drought remains an important stressor threatening the potential future river sustainability. Furthermore, anthropogenic pressures also vary by river size. Large rivers (stream orders >6) are projected to experience the highest anthropogenic pressures, followed by medium rivers (stream orders 4–5), whereas small rivers (stream orders 1–3) remain comparatively less impacted across all scenarios. Our reach-scale analysis provides a refined understanding of human-river interactions and offers critical insights for targeted water management under climate change.