Sensitivity of imperviousness determination methodology on runoff prediction

AbstractImperviousness in urban catchment is defined by Total Impervious Area (TIA) or Effective Impervious Area (EIA). The methodology of imperviousness determination considers its significance in terms of its connectivity and can affect the runoff determination. This paper evaluates the sensitivity of various impervious estimation methodologies on runoff prediction. Four types of imperviousness were used for distributed hydrological modeling. Green–Ampt parameters were determined through field experiments by Tension Infiltrometer. The runoff was simulated by using two indirect methods of EIA estimation and the results were compared. It was observed that the predicted runoff was 205% more if EIA estimated by indirect method was used in the model in place of EIA estimated by direct method. Also the peak runoff was found to be maximum at TIA value of 64.3%. Further TIA was found to increase the peak runoff by 398% than the runoff predicted by directly estimated EIA.