Odpływ kolektorem deszczowym przy czasoprzestrzennej zmienności opadu

Presented are the assumptions for a mathematical model which describes the unsteady flow of surface runoff and the unsteady discharge of storm water from the sewer.Surface runoff is characterized in terms of the kinematic wave equation.Since it has been assumed that the wastewater stream in the sewer follows gradually varied,one-dimensional,free-surface flow pattern, it is possible to make use of the Saint-Venant equations in thier full formulation.The equations of the mathematical model ( appropriately determined initial and boundary conditions) are solved by a finite difference numerical method.The algorithm of the solution has been coded as a computer programme (ALFA),thus making it possible not only to simulate the operation of the sewer system under arbitrary feeding conditions,but also to perform technical and cost-effectiveness analyses.Considered are two flow patterns in the storm sewer.In pattern (A)rainfall of a time-variable intensity is assumed to move downstream (in the direction of the direction of the outflow cross-section ) at a constant velocity.In pattern (B),reinwater is assumed to trawel upstream at the same velocity.When formulating the numerical example,consideration has been given to the geometry,slope and pipe roughness of the sewer,as well as to relevant parameters of the adjacent catchment area.The distributions of effective rainfall intensity for every part of the catchment is determined for pattern (A) and pattern (B).Computations are performed using the ALFA programme.Some of the results obtained are presented in graphical form to visualize how the storm water level in the cross-sections of the sewer varies with time forn the flow patterns considered.