Hydrology and Runoff

Gumbel's extreme value distribution expresses the design flood magnitude $x_T$ for return period $T$ as:

Options:

• (A) $x_T = \bar{x} + K \sigma_x$, where $K$ is the frequency factor
• (B) $x_T = \bar{x} \cdot T$
• (C) $x_T = \bar{x} / T$
• (D) $x_T = \sigma_x \sqrt{T}$