经济社会与生态环境竞争用水的水价研究

Water pricing model of competitive water use for the economy,society and environment

针对我国水资源开发利用不合理造成的生态环境问题,探讨如何通过水价的市场调节作用,保障经济社会与生态环境协调发展的总用水效益最优的理论和方法。以用水总效用最大为原则,以经济社会消费预算、可利用水资源量为约束,建立水资源需求函数模型;以供水总效益最大化为目标,建立考虑经济社会用水全成本代价的水资源供给函数模型;迭代求解水资源最优配置的供需均衡水价。在考虑基本生活用水价格刚性及经济社会发展水平条件下,北京市2000年总用水40.4亿m3,最优分配方案为经济社会合理用水量24.76亿m3和生态环境可用水量15.64亿m3,总效益最优为440亿元,用水综合水价为8.01元/m3。研究发现,如果生态环境基本用水得不到满足,以现状经济社会承受能力为约束确定的水价,不能补偿经济社会占用生态用水的外部损失,无法促进水资源在生态环境与经济社会之间的最优配置。

The unreasonable utilization of water resources causes serious ecological problems in our country. The theory and method of water pricing that ensures the maximum benefit across the total range of economic, social and ecological water uses are discussed. With the maximum utilization of water resources as a guiding principle, a function for water demand was established using the social and economic water consumption budget and the available water resource amount as restraints. With the target of maximum total profit, a function for water resources supply that considers the whole cost of social and economic water use was established. By iteratively solving the functions, an ideal water price for optimum allocation of water resources was identified. Considering the price inelasticity of basic domestic water use and the level of economic development in Beijing, a reasonable allocation for the year 2000 of the total water quantity, which was 4.04 × 10^9 m^3, was 2.476 × 10^9 m^3 for social and economic use, and 1.564 × 10^9 m^3 for ecological use. The total benefit was 4.40× 10^10 yuan, and the comprehensive water price was 8.01 yuan/m^3. The results indicate that if the basic water demand of the ecological environment cannot be satisfied, the water price determined to be affordable cannot compensate for the extra cost of more social and economic water use, and water resources cannot be reasonably allocated.