Which scenario would have a higher adjusted intensity?

Which scenario would have a higher adjusted intensity?

• A. 10 minutes of TOC for a 10-year design storm frequency
• B. 30 minutes of TOC for a 10-year design storm frequency
• C. 10 minutes of TOC for a 25-year design storm frequency
• D. 30 minutes of TOC for a 25-year design storm frequency

Answer: (C)

The scenario with a higher adjusted intensity is associated with a shorter duration of the Time of Concentration (TOC) combined with a higher design storm frequency. The rationale behind this is that the intensity of rainfall increases when the storm frequency is elevated, as it represents a more severe rainfall event. In this question, option C combines 10 minutes of TOC with a 25-year design storm frequency. A 25-year design storm has a greater intensity compared to a 10-year design storm, signifying a more extreme event that is statistically expected to occur once every 25 years. Because intensity is defined as the amount of rainfall over a specific duration, a shorter duration (10 minutes) during a more intense storm leads to a higher adjusted intensity value. The other scenarios either involve longer durations or a lower frequency of rainfall events. Longer durations tend to distribute the rainfall over more time, typically resulting in lower intensity values. Likewise, the 10-year design storm frequency generates less intense rainfall compared to the 25-year frequency, hence contributing to lower overall adjusted intensity values in those scenarios.

The scenario with a higher adjusted intensity is associated with a shorter duration of the Time of Concentration (TOC) combined with a higher design storm frequency. The rationale behind this is that the intensity of rainfall increases when the storm frequency is elevated, as it represents a more severe rainfall event.

In this question, option C combines 10 minutes of TOC with a 25-year design storm frequency. A 25-year design storm has a greater intensity compared to a 10-year design storm, signifying a more extreme event that is statistically expected to occur once every 25 years. Because intensity is defined as the amount of rainfall over a specific duration, a shorter duration (10 minutes) during a more intense storm leads to a higher adjusted intensity value.

The other scenarios either involve longer durations or a lower frequency of rainfall events. Longer durations tend to distribute the rainfall over more time, typically resulting in lower intensity values. Likewise, the 10-year design storm frequency generates less intense rainfall compared to the 25-year frequency, hence contributing to lower overall adjusted intensity values in those scenarios.