Select Priority Villages for Investments on Rural Sewage Treatment in Chinese Provinces

Rural sewage treatment (RST) has emerged as a critical issue in the restoration of China’s environment. Unlike in urban areas, the planning and management of RST in rural settings are significantly more complex and often constrained by limited budgets. It is significant and urgent for provincial or municipal governments to identify the villages with the highest priority for RST investment. This study proposes a decision-making model to prioritize villages for RST investment, balancing economic and ecological benefits with life-cycle costs. The model was applied across 104,246 villages in Guangdong, Henan, Hunan, Shanxi, Qinghai, and Liaoning Provinces in China, and it successfully generated priority maps for each province. Results indicate that the return on investment (ROI) for the top 5% of villages in Guangdong Province reached 1.75, which is 20.3% higher than that of random investments. Furthermore, the corresponding average revenue was 6 times greater than those of randomly selected villages. The model also demonstrated strong performance in the other 5 provinces. Factor importance analysis, utilizing random forest regression models alongside SHAP methodology, reveals that population size is the most influential factor in prioritization. The decision-making model offers scientific and efficient solutions for optimizing RST investments while maximizing marginal benefits and enhancing the efficiency of ecological protection funds.