Gradually accumulated sediment behind the dams will raise the level of the streambed. Eventually high water flows can overtop the channel banks and begin spreading across the long-dry floodplain. The ground water table rises, and riparian vegetation reappears. How much water can be stored in the aquifer will depend on site characteristics. How fast this stored water returns to the stream channel depends on aquifer characteristics and how far this water is made to travel horizontally through the aquifer before it is allowed to reappear and join the surface flow.
Riparian vegetation shades the soil, lowers wind currents, and reduces soil compaction.
In combination this increases percolation of snowmelt, rainfall, and flood water through the soil and into the aquifer beneath for storage. Reports suggest recharge of the aquifer exceeds the water loss by increased evapo-transpiration from riparian vegetation. In addition, restored wetlands and riparian areas also improve water quality. The natural services they offer include filtration, adsorption, volatilization, precipitation of dissolved solids, microbial decomposition, and vegetative uptakes of pollutants. They attenuate flood flows from storm events and snowmelt.