Flood Routing

Civilisation has always developed along rivers, whose presence guaranteed access to and from the sea coast, irrigation for crops, water supplies for urban communities and latterly power development and industrial water supply. The many advantages have always been counterbalanced by the dangers of floods and, in the past, levees or flood banks were built along many major rivers to prevent inundation in the flood season. In more recent times storage reservoirs have been built as the principles of dam construction became better understood and other measures like relief channels, storage basins and channel improvements are continually under construction in many parts of the world. It is important for such works that estimates can be made of how the measures proposed will affect the behaviour of flood waves in rivers so that economic solutions can be found in particular cases. Flood routing is the description applied to this process. It is a procedure through which the variation of discharge with time at a point on a stream channel can be determined by consideration of similar data for a point upstream. In other words it is a process that shows how a flood wave can be reduced in magnitude and lengthened in time (attenuated) by the use of storage in the reach between the two points.