Advancement in the hyporheic exchange in rivers

Surface subsurface exchange(hyporheic exchange)across the river bed plays an important role in the fate of solutes and contaminants in rivers.The main mechanisms of hyporheic exchange include pumping exchange and turnover exchange. The pumping exchange is driven by pore water flows induced by head gradients Such head gradients are typically due to interactions between currents and the streambed topography. Turnover occurs with the moving bedforms trap and the released the in terstitial fluid.The main factors of influence on hyporheic exchange are as follows:the riverine flow rate,the hydraulic conductivity,the bedform,the channel curvature,the streambed heterogeneity and the background conditions.The interplay of the reactive solutes and colloids is reviewed,and the ideas for further studies on hyporheic exchange are proposed.