建筑屋面雨水有压回补地下水理念与潜力评估

Concept and assessment of utilizing rooftop rainwater for pressurized groundwater recharge

城市雨水回补地下水对增加城市地下水资源、减轻内涝灾害具有重大意义。屋面雨水水质较好,且具有高水头特点,并无需外界提供电能、不占据多余空间,可实现雨水收集、快速净化,形成屋面雨水有压回补地下水模式,增加地下水回补率。该技术理念提出后,尚处于研究阶段,故本文以天津大学新校区为研究区,通过水泵加压回补地下水的现场数据推导出了半经验公式,选取与实地状况基本相符的渗透率等相关参数,对该模式进行相关计算与潜力评估。利用天津市暴雨公式计算了不同降雨重现年及历时的设计雨强,并计算出本模式应用于研究区的不同设计情况下的回补率。计算结果显示,回补率与降雨历时(建筑屋面汇水或滞留时间)呈正相关关系;假设建筑屋面雨水滞留时间为24 h时,25年一遇以内降雨回补率大于90%,50年一遇和100年一遇降雨回补率达85%以上。本文论证了该种模式具有很强的应用价值,对雨水回补地下水技术研究有一定的参考价值。

Urban groundwater recharge with rainwater is of great significance for increasing urban groundwater resources and alleviating water-logging problems.The rooftop rainwater has good water quality and high pressure head.It can be collected and treated rapidly and then recharged into the groundwater under pressure without external power demand and without occupying extra space area.However,this proposed concept is still under research.Therefore,this study took the New Campus of Tianjin University as the research site to perform calculations and assess potentials for this rainfall utilization mode.The semi-empirical formula was developed from field test data of groundwater recharge under pump pressure.The realistic parameter values were selected in the calculations.The design rainfall intensity of different rainfall recurrence intervals and durations was calculated by using the rainstorm formula for Tianjin,and the rainwater replenishment rate was quantified for this rainfall utilization mode at the study site under different design conditions.The quantification results show that the replenishment rate is positively correlated with the rooftop rainwater detention time.Assuming the rooftop rainwater detention time 24 h,the rainwater recharge rate is greater than 90%for rainfall smaller than the 25-year storm;and for the rainstorms with recurrence interval of50 or 100 year,the rainwater recharge rate is over 85%.This study demonstrates that this rainwater utilization mode has a high application value and can serve as a reference for research on technologies for the groundwater recharge with rainwater.