From Climate-Constrained to Regulation-Dominated: A Shift in Arid Oasis Ecosystem Dynamical State

The downstream Heihe River Basin (HRB) is a quintessential coupled human-water system, where ecosystem sustainability is governed by engineered water management. Although the Ecological Water Conveyance Project (EWCP) has visibly promoted greening, the quantitative impacts of this hydrological forcing on ecosystem organization and stability remain unclear. Here, we apply an Eigen Microstate and Entropy Theory (EMET) framework to long-term NDVI data (2001–2024) to characterize ecosystem evolution under this non-stationary regulation. Our analysis reveals a stepwise increase in ecosystem entropy across the three conveyance periods, with vegetation dynamics responding synchronously to water inputs in the first two periods but exhibiting a one-year lag in the third following sustained high flows. Concurrently, the linkage between vegetation entropy and upstream precipitation entropy weakened markedly after 2007, signaling a transition from a hydroclimate-constrained regime to one dominated by human regulation. Mode decomposition shows that the shift from an ordered, low-entropy state to a complex, higher-entropy state is primarily driven by oasis expansion along the West River corridor and intensified agricultural activity after 2008. The latter is associated with a sharpening phenological contrast between cropland and natural vegetation, amplifying heterogeneity within the oasis. Our findings demonstrate that managed water inputs have fundamentally reconfigured the oasis’s structural complexity, shifting its dynamics from climate-buffered to human-shaped, with direct implications for future water allocation and ecosystem management strategies.