Hi, I am trying to calibrate a subcatchment. I have semi-automatically tried to calibrate catchment width, slope, Manning's n for pervious and impervious, depression storage for pervious and impervious. I came up with a flow curve shape which looks like the measured flow but the modelled flow is starting 30min earlier. I tried to change many of those parameters I described but still I can not reduce the 30min gap. Since it is a very small catchment I don't think this is due to spatial distribution of rainfall. So any other idea why modelled flow starts 30min before measured?