Beaver Dams
Beavers are one of the more well-known biogenic forces through which geomorphology is shaped. Beavers create dams in order to slow running water, protect themselves against predation, and keep water subcritical and deep (which prevents freezing during the winter).
Beaver dams impact stream morphology in much the same way human-made dams do, albeit on a smaller scale. Slower stream currents increase the rate of deposition in the channel; the blockade itself can also cause increased erosion at the edges of the channel as water that flows over the ends of the dam is higher velocity and higher power; the water level behind the dam is increased, which enhances hyporheic zone fluxes (fluxes between growndwater and surface flow); because beaver dams are not as all-encompassing of the channels in which they reside as human-made dams, they often lead to increased channel complexity.