To explore the phenomena of early peak arrival and trailing of non-Fickian migration, the solute migration experiment of a rough single fracture is carried out, the solute migration characteristics and migration mechanism in the rough single fracture are summarized, and the phenomena of early peak arrival and trailing are analyzed and explained in combination with the boundary layer theory. The results show that there is a good linear correlation between the peak arrival time, the trailing time and the thickness of the boundary layer; The boundary layer has a significant effect on the solute transport in fractured media, that is, the smaller the flow velocity is, the greater the thickness of the boundary layer is, the more solutes remain in the boundary layer, and the lower the solute acquisition rate is; the peak advance and trailing of solute penetration curve in the rough single fracture are caused by the joint action of the main flow area dominated by the inertial force in the fracture center and the boundary layer area dominated by the viscous force on the fracture wall. Among them, the peak arrival time is mainly controlled by the convection factor in the main flow area and the existence of the boundary layer area has a great influence on the trailing time.

The existing Technical Guidelines for Environmental Impact Assessment-Groundwater Environment(HJ 610-2016) is not clear enough in the identification of environmental impacts, current situation investigation and forecast evaluation in the groundwater environmental impact assessment of water conservancy and hydropower projects. Meanwhile, the prediction of the project's impact on the groundwater flux and elevation is not covered by this guideline. Combined with the Dianzhong Water Diversion project, based on the characteristics analyzing of water conservancy projects, this paper elaborates the indicators to identify the impacts on groundwater environment in different project stages of water conservancy and hydropower projects, outlines the target types and work priorities of groundwater environment protection in different project stages, and summarizes the difficulties and main technologies of predicting the impacts on the groundwater environment. This paper indicates that the groundwater environmental protection should be carried out in combination with the scope of influence of on-site investigation, exploration, monitoring and engineering identification, and it is better to carry out numerical simulation research in areas with complex groundwater environments. Finally, the specific foothold of the groundwater environmental impact assessment for water conservancy and hydropower projects is given.