统计与数据科学学院知识库

  甘肃省面临严重的水资源短缺问题，人均水资源占有量仅占全国的四分之一。传统观点认为用水效率提高会使得水资源使用量减少，各地都将提高水资源利用率作为保护环境的重要措施之一，然而，越来越多的学者提出了水资源回弹效应，即用水效率的提高不一定会带来水资源消耗量的减少。出现这种情况主要是由于用水效率提高后，所产生的替代效应、价格效应和产出效应会带来新的水资源需求。高效利用水资源作为缓解甘肃省水资源短缺的重要措施，其所达到的效果可能会因为水资源回弹效应的存在被部分或全部抵消，甚至如果发生超过100%的回弹效应，会严重影响到甘肃省经济可持续发展，为了助力甘肃省经济与水资源的协调发展，有必要测算该地区的水资源回弹效应。

  本文以社会核算矩阵为数据基础，构建了以生产用水为生产要素，生活用水、生态用水为商品的静态、动态CGE（Computable general equilibrium model）模型，来研究甘肃省水资源回弹效应，同时分析了提高用水效率所带来的经济效应和节水效应，以便重新审视用水效率与经济发展之间的联系，得到的结论如下：

  （1）提高各部门生产用水效率会促进GDP、政府收入、企业收入、居民收入、进口总量、出口总量上升，即生产用水效率越高，越能刺激甘肃省经济发展，并使得农业、制造业等高耗水行业部门产出增加，同时减少了各部门的用水量，而导致生活用水量和生态用水量上升。

  （2）提高用水效率时，甘肃省宏观层面存在水资源回弹效应，且不同部门之间差异较大，除水的生产和供应业外，其它部门均存在部分回弹情况，其中，制造业的回弹效应最大，即提高制造业部门的用水效率所带来的实际节水效果不理想。农业、采矿业、燃气生产和供应业、建筑业、服务业部门回弹效应均小于50%并大于0，即提高用水效率后的理论水资源节约量部分被抵消，节水政策只实现了一部分，并且各部门的水资源回弹效应随着用水效率的提高而不断增加。

  （3）从长期来看，各部门的产出水平都随着生产用水效率的提高而出现不同程度的增长，其增长速度最快的为制造业，最慢的为建筑业。各部门水资源消耗量的增长速度从快到慢依次为制造业、农业、采矿业、水的生产和供应业、燃气的生产和供应业、服务业、建筑业。生活用水量、生态用水量也呈现出逐年增加的趋势。由于用水效率的提高使产品生产成本下降，使得如农业、制造业等高耗水部门产品竞争力提高和出口量增加，进而导致整体经济发展过程中对水资源需求的增加，所以回弹效应也呈现出逐年增加的趋势。

  Gansu Province is facing a serious water shortage, with only a quarter of the country's per capita water resources. However, more and more scholars have proposed the water rebound effect, that is, the improvement of water use efficiency does not necessarily lead to a decrease in water consumption. This is mainly due to the substitution, price and output effects that result from increased water use efficiency and lead to new demand for water resources. As an important measure to alleviate the shortage of water resources in Gansu Province, the effect of efficient use of water resources may be partially or completely offset by the existence of water resources rebound effect, and even if the rebound effect exceeds 100%, it will seriously affect the sustainable economic development of Gansu Province.

  Based on the social accounting matrix, this paper constructs a static and dynamic CGE (Computable general equilibrium model) model with production water as the production factor and domestic water and ecological water as commodities to study the rebound effect of water resources in Gansu Province, and analyzes the economic and environmental effects brought about by improving water use efficiency, so as to re-examine the relationship between water use efficiency and economic development.

  (1) Improving the production water efficiency of various sectors will promote the increase of GDP, government revenue, enterprise income, household income, total imports and total exports, that is, the higher the production water use efficiency, the more it can stimulate the economic development of Gansu Province, and increase the output of high water-consuming industries such as agriculture and manufacturing, while reducing the water consumption of various departments, resulting in the increase of domestic water consumption and ecological water consumption.

  (2) When improving water use efficiency, there is a rebound effect of water resources at the macro level in Gansu Province, and there is a large difference between different sectors, except for the water production and supply industry, there are some rebound situations in other sectors, among which the rebound effect of the manufacturing industry is the largest, that is, the actual water-saving effect brought about by improving the water use efficiency of the manufacturing sector is not ideal. The rebound effect of agriculture, mining, gas production and supply, construction and service industries is less than 50% and greater than 0, that is, the theoretical water resource savings after improving water use efficiency are partially offset, and the water conservation policy is only partially realized, and the water resource rebound effect of each sector increases with the improvement of water use efficiency.

  (3) In the long run, the output level of each sector has increased to varying degrees with the improvement of production water efficiency, with the fastest growth rate in the manufacturing industry and the slowest in the construction industry. The growth rate of water consumption in each sector is in order of manufacturing, agriculture, mining, water production and supply, gas production and supply, service industry, and construction industry. Domestic water consumption and ecological water consumption are also increasing year by year. The rebound effect is also increasing year by year due to the increase in the production cost of products due to the improvement of water use efficiency, which improves the competitiveness of products and increases the export volume of high-water-consuming sectors such as agriculture and manufacturing, which in turn leads to the increase in the demand for water resources in the process of overall economic development.