Discussion On Gradient Structure Setting Of Increasing Block Rate And Influence On Water Consumption

The increasing block rate refers to the implementation of lower price within the water consumption quota and progressive price increase exceeding the quota on the basis of reasonably verifying the basic consumption of residential or enterprise business water.For urban water use in China,the increasing block rate includes a blocked water price system for domestic water use and a progressive price increase system for non-residential water use that exceeds the quota.A scientific and effective gradient structure can promote the implementation of water saving priority,but the current gradient setting of water volume and water price has not fully exerted the incentive mechanism to save water in the whole society.The main research contents and conclusions of this paper are as follows:1.Taking 288 cities above the prefecture level for residential domestic use and 159cities above the prefecture level for non-residential use implementing the increasing block rate,this paper analyzes the current situation and characteristics of the gradient structure setting.The results show that:（1）In the increasing block rate for residential domestic use,the average basic water volume of the first block is 198 m~3/（household·year）,the average ratio of the cut-off point of the blocked water quantity is 1:1.52,the water quantity is set high,and the water quantity difference between the steps is relatively loose.The average basic water price for the first block is 2.03 yuan,and the average water price ratio between the blocks is 1:1.52:2.67.60%of the cities above the prefecture level are lower than the prescribed value in the guidelines issued by the National Development and Reform Commission and the Ministry of Housing and Urban-rural Development（1:1.5:3）.The proportion of stepped water fee in per capita disposable income is 0.2%～1.4%,residents’perception of gradient structure is low,and the effect of motivating residents to actively reduce water consumption is relatively limited（2）In the incremental price increase for non-residential water use exceeding the quota,the average basic water price of the first block is 3.13 yuan.Due to the low water price,the water fee only accounts for 0.02%～0.5%of the output value,which is not conducive to promoting enterprises’water saving awareness improvement and water saving behaviors occur;three,four and five steps are mainly implemented in water volume classification and price increase rate.The higher the step difference,the smaller the water gradient interval between the series.2.Taking Shanghai as an example,the price elasticity coefficients of residential water and non-residential water（including industrial water and public domestic water）were discussed through regression models of time series and space series to analyze the impact of increasing block rates on water consumption,the results show that:（1）For residential water use,from the single water price to the implementation of the increasing block rate（2012～2013）,the three-stage water consumption can be reduced by 2.49%,6.12%and 4.75%respectively;in recent years,considering the water supply Due to cost changes and other reasons,the increasing block rate has been adjusted in a gradient structure（from 2020 to 2021）.Specifically,the water volume remains unchanged,the water price increases,and the water consumption is reduced by2.42%,1.87%,and 1.50%from the original ladder level.The implementation of the increasing block rate is conducive to promoting the reduction of water consumption,but it has not released sufficient water saving potential.（2）For non-residential water use,from a single water price to an over-quota incremental price increase（from 2020 to 2021）,the impact on water consumption will increase with the increase in the level of the ladder,and the impact on industrial water will be in the first step（2020～2021）.The basic water consumption and the fourth step（over 50%of the water consumption）were reduced by 15.24%and 61.86%respectively,and the public domestic water consumption was 4.15%and 20.28%respectively.The implementation of over-quota progressive price increases can significantly promote the decline of water consumption and help limit high water consumption behaviors.3.Using the Ramsey pricing method,considering the principles of cost recovery and reasonable profit,in view of the loose water volume setting and low water price in the first step,4 different gradient structure optimization scenarios were set for the intersection of residential and non-residential water use.to explore the focus of gradient structure adjustment through the impact on water consumption.The results show that:（1）On the premise of maintaining the long-term marginal cost of residential water,the cut-off point of the stepped water volume is reduced by 50m~3/（household·year）and 40m~3/（household·year）,respectively,compared with maintaining the existing gradient structure,the water price rises less,though it can produce higher water saving effect in the second and third steps,and also guarantee the fairness of the first step.Therefore,the adjustment of the gradient structure of residents’domestic water use is to reasonably adjust the gradient of the water volume and improve the residents’awareness of water saving.（2）In terms of the incremental price increase for non-residential water use exceeding the quota,the basic water price is increased by 25%～35%from the current gradient structure,which can produce a strong water saving effect within the basic water volume,which is an even water saving incentive optimization strategy.Therefore,the key point of the gradient structure adjustment of non-residential water use is to gradually increase the basic water price of the first step,and to promote enterprises to actively save water.