Water Resources and Environmental Engineering

Time of Concentration

The time runoff takes to travel from the hydraulically most distant point of a watershed to the outlet.

Once a storm has lasted the time of concentration, the whole watershed is contributing to flow at the outlet at once. That is why the rational method reads its rainfall intensity for a storm of exactly that duration.

It is usually built up from segments — sheet flow, shallow concentrated flow, channel flow — each with its own travel time. A longer time of concentration means a lower design intensity and a lower peak.

How much of the FE Civil exam is Water Resources and Environmental Engineering?