Urbanisation is defined as the concentration of people in urban settlements with associated modification in land use occupancy i.e. conversion of rural lands into urban, suburban and industrial communities.The problems associated with urbanised watershed flooding range from relatively localised incidents to major incidents, resulting in inhabited areas being inundated from a few hours to several days. The large scale of urbanised flooding is usually due to the urban storm water drainage systems being under designed for the present and future changes in the land uses. Furthermore, there have been large scale encroachments on the natural drains and the river flood plains. Consequently, the capacity of the natural drains has been decreased, resulting in flooding. The problem has become more serious due to the improper design of storm water drainage systems. The increasing trend of urban flooding is a universal phenomenon. The present study has undertaken the identification and development of a real time model for prediction of increase in storm water runoff in the streams and within the watershed due to urbanisation.