海绵城市设施的降雨径流和污染负荷频谱分析方法

Rainfall runoff and pollutant load frequency spectrum analysis method for assessing the effects of sponge city facilities

海绵城市设施效果目前主要用年径流总量控制率和年径流污染物总量削减率评价,它们通过对事件数据进行累加得到.为直接分析事件,建立了适用于降雨、径流和污染事件的频谱分析方法.在方法例证研究中,年径流总量控制率显示海绵设施能够完全还原自然径流总量,最佳规模为201 m^(3).而径流频谱显示,与自然对照相比,海绵设施截留小雨(导致径流总频次减少)、对大雨控制不足,只在中雨下接近自然径流,它不能还原自然径流事件,通过计算频谱相似度得到的最大修复程度为0.66,最佳规模为238 m^(3).污染负荷频谱提供了大量细节信息,例如,没有初雨池的弃流器只在1.5~8.0 kg·hm^(-2)·d^(-1)的排污量范围内污染削减效果较好,在其他情况下效果较差.降雨频谱和年径流总量控制率的比较表明,频谱不会对原始数据做任何改变,只原样地呈现事件累积频率分布,其表征水文特征的真实性更高.

the effects of sponge city facilities are currently assessed using the volume capture ratio of annual rainfall and the reduction ratio of annual pollutant load,which are computed by accumulating all runoff events.In order to analyze these events directly,this study introduces the event frequency spectrum analysis method which is applicable to rainfall,runoff and pollutant load events.In case studies,the volume capture ratio of annual rainfall showed that sponge city facilities could fully restore the total volume of natural runoff with the optimal size being 201 m^(3).However,the runoff frequency spectrum showed that sponge city facilities harvested the complete rainfall in small rains,reducing the total cumulative frequency of runoff,while they came close to natural conditions in moderate rains,and captured less rainfall than natural conditions in heavy rains.Therefore,it could not restore natural runoff events.The maximum restoration extent of natural hydrology represented by runoff frequency spectra similarity was 0.66 with the optimal size being 238 m^(3).The pollutant load frequency spectrum indicated that,compared with the first flush diverter with a first flush tank,the first flush diverter without a first flush tank had slightly higher pollutant load reduction effectiveness within the pollutant load range of 1.5~8.0 kg·hm^(-2)·d^(-1)while the pollutant load reduction was inferior in the other cases.Compared with the volume capture ratio of annual rainfall,the rainfall frequency spectrum showed a higher authenticity in representing hydrological characteristics since the spectrum presented cumulative frequency distribution of the events without any change to the original data.