萍乡市城市地表径流污染物浓度变化特征分析及数值模拟

Characteristic analysis and numerical simulation of pollutant concentration changes of urban surface runoff in Pingxiang City

以海绵城市建设试点城市萍乡市地表径流污染物(以SS和TP为代表)浓度变化特征与预测模型适应性为研究对象,根据两场次的降雨资料及实测径流污染物浓度数据,确定所建地表径流污染物浓度变化预测模型Sartor-Boyd和p/r模型的参数,并模拟和分析了地表径流污染物浓度变化过程。结果表明:萍乡市地表径流污染物(SS和TP)浓度受初始冲刷效应的影响,降雨过程前期随雨强的峰值而达到最大,降雨过程后期污染物浓度受雨强的峰值波动影响较小;受模型参数的影响,Sartor-Boyd模型模拟值的统计学指标RPD、R^(2)、NSE均小于p/r模型的相应指标,p/r模型对萍乡市降雨地表径流污染物排放规律的预测精度较好,模型可信度较高。结合萍乡市地区降雨状况建立的p/r数学模型可为该区域海绵城市建设过程中地表径流污染物浓度的预测及管理提供参考。

The concentration characteristics of pollutants(represented by SS and TP)and the adaptability of prediction models of surface runoff in Pingxiang City,a pilot city for sponge city construction,are studied.Two sets of rainfall data and measured concentration data of runoff pollutants are used to determine the parameters of the Sarto-Boyd and p/r prediction models,and the evolution process of pollutant concentration in surface runoff are analyzed and simulated.The results show that the concentrations of surface runoff pollutants(SS and TP)in Pingxiang City are affected by the benefit of initial scouring and their peak values in the initial rainfall period reach the maximum with the peak of rainfall intensity,whereas the concentrations of the pollutants decrease obviously in the later period of rainfall,which are unlikely to be affected by the peak fluctuation of rainfall intensity.Restricted by the model parameters,the statistical indicators such as RSD,R^(2)and NSE of the Sarto-Boyd model are all lower than those of the p/r model,and the p/r model has better prediction accuracy for the surface runoff pollutant discharge law in Pingxiang City,so this model is more feasible.The p/r mathematical model established in combination with the rainfall situation of Pingxiang City can provide some reference for the prediction and management of pollutant concentration in the surface runoff during the construction of sponge city in the region.