Example: Dimensionless Time and Depth Curves
Statistical analyses were performed using updated rainfall information for a certain geographic location in the United States. This study yielded the statistical distributions shown in the figure below. Given:A 10 year return event for a certain area has the following total rainfall depths corresponding to various durations:
Find: Rainfall curves (time versus depth) for the 1-, 6-, 12-, 18-, and 24-hour durations, using the statistically derived distributions in the following figure.
Solution: First, select the distribution that corresponds to each desired duration. Then multiply the Y-axis by the total rainfall depth for that duration and the X-axis by that duration.
Solution to Example
The figure displays the results of this example. Different curve types (A, B and C from the previous graph) were used to model different duration storms. Note how the total depth increases, but overall intensity (slope of the curve) decreases as the duration is lengthened.