Reclaimed water utilization is one of the major strategies used to achieve sustainable development in China and for alleviating issues linked to insufficient water supply. This study leverages panel data encompassing 30 provinces in mainland China from 2011 to 2022 to establish a comprehensive evaluation index system for measuring the development level of reclaimed water utilization capacity and utilization effect. On the basis of this index, the development rule of coupling coordination between reclaimed water utilization capacity and utilization effect is explored using the coupling coordination degree model, Moran’s I index, and the grey GM (1,1) model. Experimental results show that the current utilization capacity and effect of reclaimed water in most provinces of China do not match. Moreover, China’s reclaimed water utilization capacity index was shown to gradually increase from 2011 to 2022. The reclaimed water utilization capacity index of the eastern region is significantly higher than the central region, which is lower than the national average, followed by the northeast region, and the western region obtains the lowest index. The calculation results of the coupling coordination model further demonstrate the coupling coordination degree between the reclaimed water utilization capacity; moreover, the effects of provinces and cities in China steadily increased, and there is a clear spatial clustering. The predicted results indicate that the abovementioned situation will likely continue until 2030. This study is anticipated to become a point of reference for relevant departments to optimize the coupling coordination degree of reclaimed water systems across different regions in China, implement differentiated measures, and promote a rational allocation of reclaimed water resources.

The rational allocation of carbon emission quotas is crucial for improving the orderly operation of carbon markets. As a major energy-consuming province in China, Jiangsu's cities must allocate allowable carbon emissions effectively to meet China's 2030 peaking target. This study aims to achieve an optimal allocation of carbon emission quotas by considering principles such as responsibility, efficiency, and equity. To accomplish this goal, we developed a three-stage progressive optimization allocation process. This process incorporates the entropy weight TOPSIS allocation model, zero-sum game-DEA model, and Gini coefficient. The initial allocation scheme revealed that cities in southern Jiangsu, which have higher economic development levels, also received higher carbon emission quotas, compromising efficiency and equity. In response, the second stage involves adjusting the allocation to optimize efficiency for each city, aligning the quotas more closely with historical levels. Finally, the third stage uses the Gini coefficient to further refine the allocation scheme, achieving a more balanced distribution that aligns responsibility, efficiency, and fairness. This research highlights the importance of a structured approach to carbon quota allocation, ensuring a balance that supports both environmental goals and equitable development.

【目的】基于黄河流域各地再生水利用不均衡发展的实际，制定差异化的区域再生水循环利用措施，为流域统筹推进污水资源化利用的规划建设和精准施策提供参考。【方法】本文以黄河流域城市群为研究对象，结合毕达哥拉斯三角模糊VIKOR多属性决策、标准差椭圆分析、冷热点分析和社会网络分析等方法，测度了2018—2022年流域城市群的再生水利用水平并分析其空间特征；在此基础上设置了差异化的流域城市群再生水利用水平提升模式并评估其模拟实施效果。【结果】①黄河流域城市群再生水利用水平的测度结果及空间分布呈现两个特征：一是城市群再生水利用水平显著提升；二是城市群再生水利用水平发展不均衡。②流域城市群再生水利用水平的标准差椭圆主要分布在西北方向；再生水利用水平的热点区覆盖了流域大部分中心地带，冷点区则位于流域的边缘地带；再生水利用水平的双向空间关联网络具有发展不均衡和结构差异化两个特征。③宁夏沿黄和呼包鄂榆城市群可采用城市群辐射型再生水利用模式，兰西、关中平原、中原和山东半岛城市群可采用中心城市辐射型再生水利用模式，晋中城市群可采用城市群虹吸型再生水利用模式提高再生水利用水平。此外，流域城市群再生水利用水平提升模式的模拟实施结果表明，提升模式在提高区域再生水利用水平方面具有显著的积极效果。【结论】采用差异化的区域再生水利用水平提升模式能够精准提高黄河流域各城市群的再生水利用水平，破解再生水利用在区域尺度上不均衡发展的难题，进一步推动流域生态保护与高质量发展。