Unit Hydrograph Parameters Versus Urbanization

Various rainfall-runoff models are based on the development of unit hydrographs, loss rate functions, and routing criteria. With models of this type, characteristics used to define the unit hydrograph, loss rate, and routing criteria need to be modified to predict runoff that would occur because of future development within a watershed. Certain aspects of this problem, particularly changes in peak flow and lag time due to urbanization, have been treated previously. It is the aim of this note to present additional information regarding the modification of unity hydrograph characteristics due to increased urbanization and to introduce techniques which can be utilized in a practical solution.