为揭示巢湖十五里河源头段暂态存储区基本特征,选择氯化钠(NaCl)为示踪剂,开展现场示踪实验。在此基础上,利用 OTIS应用程序包和 OTIS-P参数优化软件估算 OTIS模型扩散系数 D、河道断面面积 A、暂态存储区断面面积 As和交换系数α,进而计算暂态存储指标值,并以 SPSS统计软件进行回归分析。结果表明,十五里河源头段 D、A、As和α均随水文条件而变化,且α大体处于10-5~10-3数量级;近半数的暂态存储行进时间中值所占比例Fm200ed 远低于10%,表明暂态存储区对于水力传输的影响较为不足;交换通量 qs和侧向补给强度 qL平均值分别为2.45×10-3、5.66×10-4 m^3/(s·m),表明该河段存在一定的侧向补给作用。在相关性方面,水文参数与暂态存储指标大都没有表现出相关关系。总的来说,渠道化现象降低了十五里河源头段暂态存储区的溶质滞留能力,增大了溶质负荷向河流下游传输的可能性。
To investigate the fundamental characteristics of transient storage zone in the headwater stream of Shiwuli River in Chaohu Lake basin, sodium chloride (NaCl) was taken as a tracer material to conduct field tracer experiments. Based on the data sets of tracer experiments, the OTIS software package and OTIS-P optimizer, proposed by Runkel (U.S. Geological Survey), were used to estimate the model parameters such as the dispersion coefficient D, the main channel cross-sectional area A, the cross-sectional area of the storage zone As and the storage zone exchange coefficient α. Transient storage metrics were further calculated by using a series of empirical formula, and regression analysis was performed by SPSS statistical software as well. The results show that the parameters D, A, As and α vary with the hydrological conditions in the study reaches, and the order of magnitude of α is 10-5 ~ 10-3. Nearly half values of the fraction within the median travel time attributable to the transient storage Fm200ed are far below 10%,which suggests the insufficient effects of transient storage on hydraulic transfer. Mean values of the hyporheic exchange flux qs and the lateral inflow rate qL are 2.45×10-3 and 5.66×10-4 m3/(s·m),respectively,implying the existence of lateral inflow. Moreover,no significant correlations were found among most of the hydrological parameters and transient storage metrics. In general, stream channelization reduces the solute retention capacity of transient storage zone in the headwater stream of the Shiwuli River, and increases the chance of solute loads moving downstream.