The Flood Pulse Concept

Lotic Ecology (river, stream or spring ecosystems)  are dynamic places that have river-floodplain interactions that apply ecological forces on the system.  The most comprehensive approach to analyze the river-floodplain dynamics is the flood pulse concept developed by  Junk, Bayley and Sparks (Junk et al., 1989).  The big idea that came from their work is that rivers and their floodplains are integrated components of a single dynamic system.  That even though we think of them as two separate places they are components of the same system linked by strong hydrological and ecological interactions.  This means that the perceived border between a river's channel and it bank is not solid. It is porous and dynamic, allowing flows to overbank into the floodplain.   The major driving force in the concept is that the pulsing of river discharge, which in turns determines the degree of connectivity.  The discharge in a river is not constant and is continuously changing up and down, like the pulse of blood through a vessel.

This idea of a flood pulse is theorized by this paper as a major controlling force on the biotia in river-floodplains.  This means as the river pulses, leading to overbank processes, the water that connects the river channel to the floodplain bring nutrients and sediments into the floodplain.  This lateral exchange is important and often the dominent force in the nutrient cycles for some patches of the floodplain.  Water is a good solvent, so as it flows through a channel it carries dissolved and solid substances.  As the water over-banks the natural levee of a river, it will deliver not only the water carried in the flow, but aso the dissolved and solid substances.

References

Junk WJ, Bayley PB, Sparks RE. 1989. The Food pulse concept in river Floodplain systems. Can. Spec. Publ. Fish. Aquat. Sci. 106: 110-127.

http://www.nrem.iastate.edu/class/assets/aecl518/Discussion%20Readings/Junk_et_al._1989.pdf