统计与数据科学学院知识库

       水是人类生存、经济发展和社会进步的生命线，是可持续发展的重要物质基础。随着经济的高速发展、人口的增加和城镇化进程的加快，我国水资源供需矛盾日益加剧，水资源与经济社会可持续发展的要求越来越迫切。加强水资源管理，推进水资源合理开发，提高水资源利用效率、效益和实现水资源可持续利用是当代水利工作的重要任务。在市场经济条件下，开展行政管理与市场机制相结合的水权交易工作，是优化水资源配置，加强水资源节约和保护的重要措施。我国在2015年正式开始水权交易试点工作，目前该工作已经基本完成。通过对我国水权交易试点政策效果及其作用机制的实证分析，可以深入认识水权交易试点政策对水资源利用效率的影响路径，对进一步完善水权交易机制，建立健全水权交易市场，提高水资源利用效率和充分发挥市场在资源配置中的决定性作用具有现实意义。

       本文首先梳理了近年来学者们在水资源利用效率、水权交易和我国水权交易试点三方面的研究，重点总结了水资源利用效率的测度方法和我国水权交易试点作用实证研究的不足；之后在深入分析水权交易概念和理论基础、可交易水资源利用效率提升机理的基础上，提出水权交易对水资源利用效率的可能影响机制；然后介绍我国水权交易试点省份的水权交易相关制度和具体实践，并运用考虑非期望产出的超效率全局 SBM 模型测算我国大陆 31 省（区）2005-2019 年的水资源利用效率，同时从时空两个维度分别分析了我国整体水资源利用效率和水权交易试点省份水资源利用效率变化情况；基于水资源利用效率测算结果，运用回归控制法对水权交易政策进行了反事实分析，并运用中介效应模型对水权交易政策提升水资源利用效率的可能影响机制进行检验，得出以下结论：

       1.水资源利用效率测算结果显示，从时间变化趋势来看，近十几年我国整体水资源利用平均水平不高，提升空间较大。从空间分布特征来看，各省水资源利用效率地区差异悬殊，整体呈现“东高西低、沿海高内陆低”的分布状态。试点省份水资源利用效率的时间变化趋势和异质性变化表现一定程度反映了水权交易政策对水资源利用效率的提升作用。

       2.基于回归控制法的水权交易政策效果评估结果表明，水权交易政策具有显著提高试点省（区）水资源利用效率的作用，且安慰剂检验结果显示 4 个试点省（区）水权交易政策对水资源利用效率的提升效果均在 10%的统计水平下显著，且这种提升作用具有区域差异性，其中广东的政策效果显著高于其他 3 个试点省份，河南和内蒙古的政策效果较好，甘肃的政策效果最小，可能与试点省份的水资源利用水平和水权交易开展的具体形式有关。

       3.通过对水权交易政策影响水资源利用效率的作用机制检验，发现水权交易政策能够有效促进用水结构调整、激励节水和提高中水回用，进而提升水资源利用效率。其中，中水回用的中介效应最高，具有完全中介作用，节水中介效应次之，用水结构调整中介效应最低。

        Water is the lifeline of human survival, economic development and social progress, and an important material basis for sustainable development. With the rapid development of economy and society, the increase of population and the acceleration of urbanization, the contradiction between the supply and demand of water resource in China is becoming increasingly serious, and the demand for sustainable development of water resource, economy and society is becoming more and more urgent. Strengthening water resource management, promoting the rational development of water resource, improving the efficiency and benefit of water resource utilization and realizing the sustainable utilization of water resource are the important tasks of contemporary water conservancy work. Under the condition of market economy, it is an important measure to optimize the allocation of water resource and strengthen the conservation and protection of water resource to carry out the trade of water rights with the combination of administrative management and market mechanism. China officially started the pilot work of water rights trading in 2015, and this work has been basically completed. Through the empirical analysis of water rights trading pilot policy’s effect and its mechanism of action in our country, we can deeply understand the path of water rights trading policy impacting on water resource utilization efficiency, and this has a realistic significance to further improve water rights trading mechanism, establish and improve water rights trading market, improve water resource utilization efficiency and make the market play a decisive role in the allocation of resources.

        This paper firstly reviews the recent researches on water resource utilization efficiency, water rights trading and pilot water rights trading in China, and mainly summarizes the shortcomings of the measurement methods of water resource utilization efficiency and empirical researches on the role of pilot water rights trading in China. Then, based on the indepth analysis of the concept and theoretical basis of water rights trading and the mechanism of improving the utilization efficiency of tradable water resource, the possible influence mechanism of water rights trading on water resource utilization efficiency is proposed. Then, the relevant system and practices of water rights trading in pilot provinces of China are introduced，and the water resource utilization efficiencies of 31 provinces in mainland China from 2005 to 2019 are calculated by using superefficiency global SBM model of undesirable output. At the same time, the changes of water resource utilization efficiency in China and the water rights trading pilot provinces are analyzed from the spatio-temporal dimensions. Based on the calculation results of water resources utilization efficiency, the regression control method is used to conduct counterfactual analysis on the water rights trading policy, and the mediation effect model is used to test the possible influence mechanism of water rights trading policy to improve water resource utilization efficiency. The conclusion is drawn as follows:

         1.The calculation results of water resource utilization efficiency show that the average level of water resource utilization in China is not high in recent decades in terms of time, and there is a large space for improvement. From the perspective of spatial distribution characteristics, the regional differences of water resource utilization efficiency in each province are great, and the overall distribution state is“high in the east and low in the west, high in the coastal areas and low in the inland areas”.Temporal variation trend and heterogeneity variation of water resource utilization efficiency in pilot provinces reflect the improvement of water rights trading policy on water resource utilization efficiency to a certain extent.

         2.Water rights trading policy evaluation results based on regression control method show that water rights trading policy has a significantly positive role in water resource utilization efficiency of pilot provinces, and the results of placebo test show that the effects of water rights trading policies in four pilot provinces promoting water resource utilization efficiency are significant under the 10% level of statistical level, and the promotion effects are regional differences, Guangdong’s policy effect is significantly higher than the other three pilot provinces, Henan and Inner Mongolia's policy effects are better than Gansu’s, which may be related to the level of water resource utilization and the specific form of water rights trading in the pilot provinces.

       3.By examining the mechanism of water rights trading policy's influence on water resource utilization efficiency, it is found that water rights trading policy can effectively promote adjustment of water use structure, encourage water saving and improve reclaimed water reusing, and then improve water resource utilization efficiency. The mediating effect of reclaimed water reusing is the highest, followed by adjustment of water use structure, and the mediating effect of water saving was the lowest.