Evaluating and optimizing the ecosystem health of China’s Yellow River Basin based on emergy analysis and multi-objective decision method

The Yellow River is an important ecological shelter zone and one of China’s economic belts. Under the national strategy of ecological protection and high-quality development of the Yellow River Basin (YRB) and the goal of carbon peak and carbon neutralization, there is an imperative to achieve healthy development of the YRB’s ecosystem. This study uses emergy analysis, multi-objective decision method, synergy degree model, and obstacle degree model to evaluate and optimize the ecosystem health of nine cities along the YRB in Shandong Province. Results show that the ecosystem health levels of the nine cities continuously improved from 2010 to 2019, spatially presenting the characteristics that the upstream and midstream cities were lower than the downstream, and the midstream cities rose rapidly. The synergy degree of health in this region fluctuated in the range of [− 0.009, 0.080]. The key obstacle factors of the nine cities changed a lot from 2010 to 2019. It transformed from indicators focused on the driving force layer in 2010 to the state layer and response layer in 2019, which means optimization measures should be concentrated in energy resource structure and ecological environment quality. Three ecosystem health optimization paths are proposed related to regional synergy, energy resources, and ecological environment. The methodology and results of this study provide references for ecosystem health research at the regional level.