The severity of future damage is established by evaluating the damage from the current event and damage from historical records. This approach is best when past damage is similar to current damage.
Using the damage caused by an event with a known probability, the damage caused by an array of events (25-year, 50-year, 100-year, and 200-year) is estimated. Transportation facilities should be designed to at least a 10-year event so storms with a recurrence interval of 2-years to 10-years are expected to result in damage that is considered heavy maintenance, which is not ER eligible.
Hydraulic Circular -17 (HEC-17) provides information that can be used to extrapolate the damage from an event with a known probability to other events. Starting with the recurrent interval of the current event, the severity of the damage, and depth of flow, a family of hydrographs can be used to estimate scour based on depth and duration of flow.
Write a short narrative, describing the severity of damage expected from likely future eligible events (i.e., 25-year, 50-year, 100-year, and 200-year).