Illustration of vertical and lateral exchange

Stream and river water make many excursions through hyporheic flow paths. The metrics in the diagram key denote the number of excursions that water makes through hyporheic flow paths per kilometer of river distance. Vertical exchange though streambed hyporheic flow paths is much more efficient compared with exchange through lateral (stream bank) hyporheic flow paths. Also, hyporheic exchange is less efficient in the Upper Mississippi River sub-basin compared with the Missouri or Ohio sub-basins. The primary reasons for different hyporheic flow efficiencies are differences in river basin slope and sediment textures that permit greater hyporheic flow in some areas compared to others.