海绵型建筑与小区年径流污染控制率计算方法探讨

Discussion on the calculation method of annual runoff pollutant control rate in sponge buildings and residential areas

【目的】年径流污染控制率是海绵城市建设中的核心控制指标,对指导海绵设施设计具有重要意义。但其设计计算过程中的计算方法与公式存在不统一或不合理的问题,须探究更适用于实际工程的计算公式。【方法】梳理了国内外对于海绵设施污染物去除率的取值来源与计算方法,分析了目前工程设计中单一海绵设施对污染物去除率的取值和地块污染平均去除率计算方法存在的问题,并对比不同地区雨水管理径流控制指标,从定义出发推导更适用于建筑与小区小尺度流域的计算方法。【结果】在建筑与小区等小尺度流域的设计中,与其他三种地块海绵设施对悬浮物的平均去除率的算法相比,采用海绵设施的有效汇水面积进行加权平均计算会更加合理;而在年径流污染控制率的计算中,引入累积污染物负荷率与累积径流体积率比例,将其转化为年平均径流污染量控制率与污染物平均去除率的乘积进行计算会更加合理。【结论】对于年径流污染控制率的计算应该积极开展试验或数值模拟,并形成适合国内实际情形的数据库。应该提高设计人员对源头海绵设施污染物去除过程的认知,避免在建筑与小区等小尺度流域的设计计算中采用不合适的公式而引起的误差。

[Purposes]The annual runoff pollutant control rate is the core control index in the construction of sponge city,which is of great significance for guiding the design of sponge facilities.However,there is a problem that the calculation method and formulas in the design and calculation process are not uniform or unreasonable,and it is necessary to explore the calculation formulas that are more suitable for the practical projects.[Methods]The sources and calculation methods of the pollutant removal rate by sponge facilities in China and abroad were sorted out,and the problems existing in the calculation method of the pollutant removal rate and the average pollutant removal rate of land plots by a single sponge facility in the current engineering design were analyzed.Through the comparison of rainwater management runoff control indicators in different regions,the calculation method more suitable for the small-scale watershed of buildings and residential areas was deduced from the perspective of definition.[Findings]In the design of small-scale watersheds such as buildings and residential areas,it is more reasonable to use the weighted average of the effective catchment area of sponge facilities for calculation compared with the other three calculation methods of the average removal rate of suspended solids in the land plots by sponge facilities.In the calculation of the annual runoff pollutant control rate,it would be more reasonable to calculate it as the product of the average annual runoff pollutant control rate and the average pollutant removal rate by introducing the ratio of cumulative pollutant load rate to cumulative runoff volume rate.[Conclusions]Experiments or simulations should be actively conducted to calculate the annual runoff pollutant control rate,so as to form a database suitable for the actual situation in China.It is necessary to improve the designer’s understanding of the pollutant removal process from the source of sponge facilities and avoid the errors caused by the use of inappropriate formulas in the design and calculation of small-scale watersheds such as buildings and residential areas.