城镇居民生活用水的需水函数分析和水价节水效果评估

结合北京市统计数据分析表明，城镇居民人均年生活用水量与居民生活用水购买力系数（居民可支配收入与生活用水水价的比值）关系十分显著，本文在此基础上．探讨并建立了城镇居民生活用水的需求函数和水价节水效果的评估方法。实例测算结果表明，北京市城镇居民生活用水购买力系数的边际弹性为0．38．亦即北京市城镇居民生活用水购买力降低1％，城镇居民生活用水量减少0．38％；提高水价具有显著的节水效果，“十五”期间北京市城镇居民用水的水价累计节水量达到了0．9亿m^3，人均年节水量2m^3；现状北京市不同收入人群城镇居民水费支出占可支配收入的比例均小于1．0％，低于国际通行的评判可承受标准值2．5％，表明北京市城镇居民对水价承受能力比较大，水价仍有较大上升空间。

Analysis of the urban household water demand function and evaluation of the water saving effect of water tariff

The statistic data of water use in Beijing City shows a strong correlation between the annual per capita urban household water consumption and the purchasing power index of water （the ratio of the discretionary income to the water tariff）. On this basis, the urban household water demand function and the evaluation method for the water saving effect of water tariff are developed. The results show that the purchasing power index of water marginal elasticity of urban household water demand in Beijing City is about 0.38, which means that if the purchasing power index of water decreases 1%, the urban household water use will decrease 0.38%. The water saving effect of water tariff is significant. From year 2001 to 2005, 90 million m3 of water has been saved and the annual per capita urban household water consumption has decreased 2.0m^3 because of the rise of water tariff. The payment for water use only accounts for less than 1% of urban residential living expenditures in Beijing City, lower than 2.5 % （the recommended criteria according to relevant researches）, so the bearing capacity of water tariff of urban residents in Beijing City is not small and the water tariff still has a room to rise.