Hydraulics of overland flow

The prediction of water discharge and characteristics of overland flow on watersheds have been of interest toengineers for many years. The most important aspect of such a problem is the study of flood charactertstics inthe area subjected to blow-up of rain storms. The overlandflow phenonenon on a watershed is considered as an unste-ady flow. It represents a complex problem in t he theore-tical analysis especially the varying infilt ration rate ofthe soil. ’the changing geometric elements and the changingwater surface profiles. An ideal mathematical model for this type of flow can be obtained through utilizing the theory of runoff.Many investigations were carried out with different approaches. to study some hydrological variables such as1nfiltration process and the nature of overland flow.Although both occur simultaneously in nature the overland flo. and infiltration process were separately studied by heae investigations through subt racting t he in filt rationfro. the rainfall to determine the overland flow.Also some investigations proposed the assumption that the landHowever some other investigations19nificant applications were performed in the field of rface irrigation considertng the assumption of a porous