Assessment of downscaling planetary boundaries to semi-arid ecosystems with a local perception: A case study in the middle reaches of Heihe River

The middle reaches of Heihe River are located in the oasis of the Gobi Desert where limited freshwater supply supports more than 1.5 million inhabitants. The intense agricultural activities are depleting the groundwater reserve. Consequently, natural landscapes and habitats are degraded. Though such development improves the livelihood of the local community, long-term sustainability of the ecosystem is at risk. Local authorities must be informed holistically to prepare for adapting to the changes and/or mitigating the impacts. The purpose of this study was to perform a regional sustainability assessment based on downscaling the planetary boundaries (PBs). We proposed a regional safe operating space framework that applied a top-down approach using the environmental monitoring data, and a bottom-up approach using knowledge from the local perception about environmental disaster. We conducted on-site samplings and interviews of residents to demonstrate the method. Overall, we showed that the middle reaches had transgressed the safe operating space, particularly on the freshwater use and biogeochemical flow dimensions. We found that the local perception acquired from interviews complemented the insufficiency of the monitoring data and provided the insightful social implications of transgressing the safe operating space, i.e., the anticipated impacts on local livelihood, for policy support.