Shifts in water availability due to environmental flows

Human society is grappling with the need to supply reliable and affordable freshwater for growing populations without destroying ecosystems. Environmental flows (EF) have been considered, and implemented, as a promising approach to sustainable water systems since its inception. However, the persistent antagonism between EF and other water demands is questionable, as the loss of hydro-ecological functions due to excessive water withdrawal (WW) could be balanced by the compensatory benefits of EF (i.e., EF improves resilience). Here, we introduce a mathematical push-pull framework to demonstrate how can EF be applied to lead to shifts in water availability explicitly in terms of magnitude and frequency. Our case study in the Yangtze River Basin reveals that EF implementation improves water availability over long time scales. We determine a boundary between EF and WW that leads to an escape from or stabilization within a stable equilibrium attraction. We use this boundary to define reasonable EF tailored to repeated, discrete WWs. Our results support the implementation of EF and its accompanying measures as part of the post-2030 eco-restoration framework.