Critical Duration definition
Critical Duration means the duration of a specific storm event (i.e., 100-year storm) which creates the largest volume or highest rate of net stormwater runoff (post-development runoff less pre-development runoff) for typical durations up through and including the 10-day duration event. The critical duration is determined by comparing various durations of the specified storm and calculating the peak rate and volume of runoff for each. The duration resulting in the highest peak rate or largest total volume is the "critical-duration" storm.
Critical Duration means the length of the storm event that produces the largest difference between post development and pre development peak flow or volume without routing post-development hydrographs through a stormwater management system.
Critical Duration means the length of time duration of a specific storm frequency event (i.e., 100-year storm) which creates the largest volume or highest rate of net stormwater runoff (post-improvement development runoff less pre-improvement development runoff) for typical durations up through and including the 10-day duration for closed basins and up through the 3-day duration for basins with positive outlets event. The critical duration for a given storm frequency is determined by calculating comparing various durations of the specified storm and calculating the peak rate and volume of stormwater runoff for various storm durations and then comparing the pre-improvement and post-improvement conditions for each of the storm durations. The duration resulting in the highest peak rate or largest net total stormwater volume is the “critical duration” storm (volume is not applicable for basins with positive outlets).