城郊排水沟渠溶质传输的暂态存储影响及参数灵敏性

Influence of Transient Storage on Solute Transport and the Parameter Sensitivity Analysis in a Suburban Drainage Ditch

选择Na Cl为示踪剂,于2013年9~10月在合肥城郊的关镇河支渠开展5次瞬时投加示踪实验.从暂态存储、侧向补给和对流-扩散等作用机制层面,设置4种模拟情景,解析暂态存储作用对于排水沟渠溶质传输规律的影响,并对OTIS模型参数进行灵敏性分析.结果表明,暂态存储对于主流区Cl-模拟浓度穿透曲线(BTCs)峰值大小影响很大,相对偏差高达24.23%~117.26%,显著高于对峰值出现时间的影响,且暂态存储影响显著超过了侧向补给作用;由相关性分析,主流区Cl-模拟浓度BTCs峰值大小和出现时间的相对偏差与As/A具有极显著相关性;4个主要参数的灵敏度排序为A>As>α>D.

From September to October 2013,five in-stream tracer experiments involving slug additions of chloride were performed in Guanzhenhe Branch,a headwater stream in suburban Hefei. From the perspective of different transport mechanisms such as transient storage,lateral inflow and advection-dispersion,four scenarios were set to analyze the effects of transient storage on solute transport in the drainage ditch. And sensitivity analysis of parameters in OTIS model was conducted. The results showed that transient storage exerted a significant influence on the peak values of simulated chloride concentration breakthrough curves( BTCs) in the main channel,and the REs( relative errors) of peak values in the BTCs ranged from 24. 23% to 117. 26%,which were much higher than those of the peak times. Meanwhile,the effects on simulated BTCs of transient storage markedly exceeded those of lateral inflow. Correlation analysis results showed that As/ A were significantly correlated with the peak value REs and the peak time RE’s,respectively.Moreover,the ranking of parameter sensitivity in OTIS model was A > As> α > D.