THE SERIAL DISCONTINUITY CONCEPT - EXTENDING THE MODEL TO FLOODPLAIN RIVERS

The serial discontinuity concept (SDC) was developed as a theoretical construct that views impoundments as major disruptions of longitudinal resource gradients along river courses. According to the SDC, dams re sult in upstream-downstream shifts in biotic and abiotic patterns and processes; the direction and extent of the displacement depend on the variable of interest and are a function of dam position along the rive r continuum. As originally formulated, the SDC did not consider intera ctions between the river and its flood plain. The new perspective pres ented herein is an initial attempt to encompass the dynamics of alluvi al flood plain rivers into the model using a three reach characterizat ion: constrained headwater reach, braided reach and meandering reach. The constrained headwater reach has conditions similar to those descri bed in the original SDC, but the braided and meandering reaches provid e a perspective that was not addressed in the model. Lateral interacti ons between the channel and the flood plain are critical to a holistic understanding of natural river ecosystems and the alterations induced by regulation. The fringing flood plain, with its diverse water bodie s and alluvial forest mosaic, is considered an integral part of the ri ver system.