Patent US 6,522,972

A method for producing a more accurate instantaneous unit hydrograph particularly for urban areas and for use in specifying the capacities of structures engineered to manage surface water runoff at the watershed catchment. The method uses map data verified by on-site inspections to obtain the input for the computer-performed calculation of initial probabilities, transition probabilities and mean waiting times, and subsequently the instantaneous unit hydrograph. This data includes the areas, links between streams, and slopes of various parts of the watershed.