# Dynamic Evaluation and Internal Driving Factors of Water Resources Green Efficiency in China
## 2 Literature Review
[36] all conducted research using spatial econometric models and found that the driving factors of water resource utilization efficiency in different regions are quite different. Through literature review, we found that:  
(1) The evaluation of water resource utilization efficiency pays more attention to the economic and environmental efficiency in the process of water resource utilization, which makes the water resource allocation process overemphasize the economic orientation and cannot reflect the ecological and social attributes of water resource utilization. As a result, the allocation of water resources cannot seek dynamic balance among multiple goals, which is not conducive to high-quality economic development and harmonious coexistence between man and nature. Based on above, water resources green efficiency in this study is defined as: in a certain period and productivity level, with a certain amount of input from other natural and social resources, such as water resources, while obtaining the largest economic output, to meet mankind's ever-increasing demands for a better life in terms of environment, health and social welfare, and to realize a virtuous circle of ecological environment in the utilization of water resources. In order to quantify the efficiency of achieving \"economic-social-ecological\" win-win in the process of water resources utilization, the damage to ecological environment caused by unexpected output is orderly reduced based on the characteristics of pollutants. (2) Both traditional DEA models and non-radial and non-angular DEA models assume that the unexpected output has the same change ratio, that is, the expected output and the unexpected output have the same production restriction law. However, the assumption of the same rate of change is contrary to the objective law of the development of things because of the differences in the characteristics of each output index [37]. Although a few literatures have made disposability hypothesis [38] for unexpected output, it is also based on the same disposability and ignores the difference of indicators. (3) Because the non-parametric DEA model estimates the efficiency value based on a certain time point and it is a static efficiency analysis, and the efficiency value only represents the technical efficiency of the time point, so it cannot evaluate the technical progress and other efficiency values. However, production is a long-term continuous process. As the primary productive force, production technology will also continue to improve. In addition to technical efficiency, the actual production process is also affected by technical progress and scale factors. (4) The existing literature mainly studies the driving mechanism of water resources utilization efficiency from external factors, and few studies the influencing factors based on the efficiency value itself. Therefore, based on the essence of the water resources green efficiency, this study will construct a water resources green efficiency measurement model from the perspective of mixed disposability in order to realize the \"economic-social-ecological\" win-win of water resources utilization. Combined with the Malmquist Total factor productivity index, the water resources green efficiency and its internal driving factors were evaluated to provide a realistic basis for the construction of water ecological civilization and high-quality development in China.