METHODS OF CALCULATING STORMWATER RUNOFF

Three different types of land areas are described with regard to surface runoff and basic formulae and methods for the calculation of storm water runoff in each area are presented. The areas have different surface characteristics with a varying percentage of impermeable surfaces, corresponding to varying degrees of urbanization. Particularly the english RRL-method for storm water runoff calculation is discussed. This method was developed by the former Road Research Laboratory in London and is basically a hydrograph method where only the runoff from impermeable surfaces is considered but still the entire storm water runoff is described. The principles of this method are outlined in the article. Current attempts at developing mathematical models for runoff calculation and mathematical physical methods of describing hydrological situations with special regard to the surface runoff are briefly reviewed. /TRRL/