PROBABILITY for the ANNUAL maximum flood magnitude to occur = \(\FRAC{1}{{Return\;period\;}} \)Calculation:\(\begin{array}{l} P = \frac{1}{T} = 0.1\\ q = 1 - p = 0.9 \end{array}\)Probability of flood at least once in next 4 YEARS= 1 – no flood in next 4 years= 1 – q4= 1 – (0.9)4 = 0.35