Adaptation of ILLUDAS for Continuous Simulation

A description is presented of the essential elements of a modified version of the Illinois Urban Drainage Area Simulator model which is used for continuous simulation. The significant changes include a daily soil moisture and initial abstraction accounting scheme coupled with the Horton infiltration model, which is used for runoff simulation of specified events. In addition, three hydrograph routing techniques are incorporated. A screening procedure is described which eliminates from simulation those events which have a low probability of being important in the analysis. An example is presented showing the calibration of a specific catchment and applying 25 yr of continuous rainfall data to obtain a simulated history of peak flows. A frequency analysis of these peaks is then performed as the final goal of the example.