我国城市人与自然耦合系统的协调度

城市作为人类生存与发展的主要空间载体,是人与自然耦合系统的典型代表。城市人与自然协调度是认识人与自然耦合机制重要内容,对揭示城市人类活动对生态环境的影响,指导城市建设具有重要意义。从水资源开发强度、土地开发强度、水资源供给能力、环境污染物排放强度与碳排放强度五个方面分析城市人与自然协调度特征,评估城市建设与发展对自然环境的影响程度,并评估了我国146个城市的协调度特征,进一步分析了城市人口规模、城市经济规模、城市社会发展水平、不同生态地理区人与自然耦合协调度的关系。结果表明：2016年城市平均协调度指数为87.90,不同城市的协调度差距很大且协调度与城市人口规模、经济规模、发展水平呈显著负相关,而六大生态地理区中,西南地区协调度最高,协调度指数为92.81,西北地区协调度最低,协调度指数为82.25。研究发现我国城市建设与发展对自然环境影响仍然较大,并表现为（1）我国城市发展总体仍处于高需求高排放的发展阶段;（2）生态环境承载力是影响城市人与自然耦合协调度的重要因素;（3）提高能源利用效率,降低碳排放强度在改善城市人与自然协调度中发挥作用。最后,从优化城市布局、提高水、能源利用效率、控制环境污染等方面提出政策建议,为评估城市生态文明建设与可持续发展提供参考与依据。

Harmonization of coupled human and natural systems in China urban area

China has experienced urbanization at high speed and at an unprecedented scale. As a key support system for human survival and development, city is a typical case of coupled human and natural systems (CHANS). Harmonization of coupled human and natural systems in urban area is an important content of understanding the coupling mechanism between human and nature, which is of great significance to reveal the impact of human activities on ecological environment and plays a key role in guiding city construction. In this study, we created a comprehensive index system with water resource intensity, land development intensity, water supply capacity, effluent intensity and carbon emission intensity to estimate the impact of urban development on the natural environment. Based on calculation of the harmonization index for 146 major cities in China in 2016, we analyzed how population scale, economic level, social development level and eco-geographical regions would relate to harmonization of coupled human and natural systems. The results show that (1) in 2016 the national harmonization index was 87.90, but there was a large range in the level of harmonization across cities, with the best city was 98.83 and the worst was 14.39. (2) The degree of harmonization was negatively correlated with city population size, and the harmonization index order was the "small and medium size city" (89.11) > the "big city" (88.10) > the "mega-city" (87.26) > the "super city" (76.12). (3) Under different economic levels, harmonization was also negatively related to the economic level. The order of harmonization index was as follows, the "class IV city"(94.02) > the "class III city"(86.83) > the "class II city"(81.56) > the "class I city"(78.07). (4) The harmonization index had a significantly negative correlation with the level of urban social development. The higher per capita GDP, the lower harmonization index. (5) For the harmonization index values of the six eco-geographical regions, the Southwest received a score of 92.81 while the Northwest only was scored 82.25. It is found that the urban construction and development in China still have a huge impact on the natural environment, which is reflected in the following aspects:(1) the urban development in China is still in the development stage with high demand and caused high emission. (2) The carrying capacity of ecological environment plays an important role on affecting the cities'' harmonization of coupled human and natural systems. (3) Improving efficiency of energy utilization and reducing intensity of the carbon emission will engage the acceleration of the harmonization of coupled human and natural systems in urban areas. Last but not least, we make some policy suggestions from the aspects of optimizing the urban layout, improving the efficiency of water and energy utilization, controlling environmental pollution, etc., which can provide reference and basis for evaluating the construction and sustainable development of urban ecological civilization.