Hydrology and Runoff

For a conservation structure designed for a flood with return period $T = 25\text{ years}$, the probability that the design flood will NOT be exceeded in any single year is $p_0 = 1 - 1/25 = 0.96$. Over a 2-year service life, the probability of non-exceedance in both years is $(0.96)^2 = 0.9216$. The hydrological risk of failure in the 2-year period (in %) is: