Table 1 should be here

2.2 Modeling

2.2.1 Conceptual model
Based on the field tests, a two-dimensional cross-section coupling flow and solute transport and reaction model was constructed in the riparian zone. The domain was 200m long and 10m high, and the slope of the bank was 45° (Fig. 1). The assumptions and simplifications of the model were the same as the model of Liu et al. (2019). The flow and chemical boundary conditions of the model were shown in Fig. 1. Due to the lack of groundwater level data and the fact that groundwater level at the long distance from the river was nearly not affected by river fluctuation (Siergieiev et al., 2015), the right boundary of the model was set as no flow boundary. The initial hydraulic head distribution of the study domain was obtained by steady simulation on a given type of boundary condition, while the initial concentration distribution of each solute was directly assigned according to the measurements.