摘要
科学、合理、高效地利用雨水资源,不仅可以缓解城市缺水状况,而且能够涵养与保护水资源、控制城市水土流失和内涝,减少水污染和改善城市生态环境等。目前世界上很多城市都开展了雨水利用方面的研究。如何科学的评价雨水利用的成本效益是城市雨水利用研究的热点。本文根据城市水文学原理和经济学原理建立了城市雨水利用成本效益分析模型,对北京市2007年267项雨水利用工程进行了分析。结果表明:①北京市雨水利用效益指数α达到了2.3,综合效益非常显著;②根据α的值,将全市分为4个区:①雨水利用无效益区(α<1.0),包括朝阳区、西城区、东城区和丰台区,占22.2%;②雨水利用低效益区(1.0≤α≤1.5),包括通州区、平谷区、石景山,占16.7%;③雨水利用利用效益区(1.5<α<3.0),共包括9个区县,占50.0%;④雨水利用利用高效益区(α≥3.0),共包括2个区县,占11.1%;③从α的空间分布来看,北京市城区的效益指数总体上小于郊区,α与各区县面积呈较好的正相关关系(r=0.65,R2=0.432),这主要是由于城区雨水利用的空间相对郊区来说受到的限制较多,可选择的雨水利用方式比较单一,多以小型的蓄水池和透水地面为主。
Efficient Urban Rainwater Harvesting （URH） can alleviate water shortage and urban soil erosion, reduce urban non-point pollution and water logging, and improve urban ecological environment. Currently, most URH projects lack an effective and full-scale Cost-Benefit Analysis （CBA） based on economy principles, while paying more attention to the calculation of the economic benefits from tap-water saving and the basic construction. Therefore, systematic and scientific CBA indices are calculated on the basis of the combination of hydrology and economy in this paper. The potential calculation formulas of typical rainwater harvesting are discussed in details, including the potential of tank, sunken grassland, man-made pools, and recharged wells. Meanwhile, the costs of rainwater project are divided into fixed cost, operating cost, and marginal cost. The benefits of rainwater project fall into 7 categories, being followed by the benefit from tap-water saving, groundwater recharging, national fiscal increase, less social loss due to less pollution, less operational costs of the municipal water discharge system, less flood control costs, and the alleviation of land subsidence. Beijing has been suffering from water shortage since 1980s. With the fast increase in both economy and population, the continuous increase in water demand has worsened the water shortage. According to the latest statistical data, the annual average volume per capita is only 245 m3 in Beijing. This amount equals to 1/8 of the national average and 1/30 of the international average. Consequently, Beijing is among the world＇ s top ten cities suffering from water shortage. On the other hand, Beijing is also seriously affected by local floods. In order to take full advantage of rainwater to alleviate water shortage, more and more Urban Rainwater Harvesting Projects （URHP） have been put into practice in Beijing. According to the statistical data, 350 URHP have been finished in 2007, 267 of which are located in the urban areas. In this paper, the model of CBA on URH is used to evaluate the 267 projects. The results are： 1） In general, Beijing＇ s rainwater harvesting projects is remarkably beneficial, with the index of benefit a reaching 2.0; 2） based on the values of α, the districts can be divided into four categories. The first class is non-benefit districts with the αvalues lower than 1.0, which includes Chaoyang, Xicheng, Dongcheng and Fengtai districts, accounting for 22.2% of the total area. The second class is low-benefit districts with the α values between 1.0 and 1.5, which includes Tongzhou, Pinggu and Shijingshan districts, accounting for 16.7%. The third class is general-benefit districts with the α values between 1.5 and 3.0, including 9 other districts, accounting for 50.0% of the total. The forth class is high-benefit districts with a values above 3.0 （included）, including 2 districts, accounting for 11.1%; 3） The spatial distribution of α shows that the projects in suburban areas are more beneficial than those in urban and central areas. Meanwhile, regression analysis reveals a positive coordination between the value of α and the area of the district （r=0.65, R2=0.423）. The results indicate that a lower a value in urban or central areas can be attributed to the limited space and rainwater harvesting style, smaller rainwater cisterns and more porous pavements for rainwater infiltration.
出处
《资源科学》
CSSCI
CSCD
北大核心
2009年第8期1295-1302,共8页
Resources Science
基金
国家重点基础研究发展计划(973)项目:"海河流域水循环演变机理与水资源高效利用-城市二元水循环系统演化与安全高效用水机制"(编号:2006CB403407)
关键词
城市雨水利用
成本效益分析
空间分布
北京市
Urban Rainwater Harvesting （URH）
Cost-Benefit Analysis （CBA）
Spatialdistribution
Beijing
