Ecological water conveyance drives human-water system evolution in the Heihe watershed, China

Watersheds are coupled with human-water systems where human, and water resources interact and coevolve with each other. Restoration management not only affects the ecosystem itself but also alters the mutual feedback relationship between humans and water, resulting in additional effects and impeding the ecological restoration process. Taking the lower reaches of the Heihe River as an example (Inner Mongolia, PR China), this study investigated the evolution of the human-water system after the implementation of ecological water conveyance using multiple data sources (e.g., remote sensing data, hydrological data, field data and socioeconomic data). We found that (1) after the implementation of ecological water conveyance, vegetation recovered in the last 15 years with an NDVI increasing from 0.10 to 0.13 across the region except some degraded areas near the river; (2) besides restoring the target ecosystem, ecological water conveyance also promoted socioeconomic development and affected the water resources utilization; (3) after 15 years' water conveyance, the coupled human-water system changed from the early ecological water deficit to the present ecological-socioeconomic water-use trade-off with negative impact resulted from agriculture expansion and water usage conflict between the middle and the lower reaches. These effects impeded the restoration of the ecological environment and aggravated the conflicts of water resources utilization within the whole Heihe watershed, consistent with of the hypothesized disturbance effect transmutation. Our results highlighted that analysis on the mutual feedback effect in the coupled human-water system, and dynamic adjustments for restoration measures are needed for sustainable watershed management.