The Kerby-Kirpich approach produces time of concentration estimates consistent with watershed time values independently derived from real-world storms and runoff hydrographs.

In hydrograph analysis, time of concentration is the time from the end of excess rainfall to the point on the falling limb of the dimensionless unit hydrograph (point of inflection) where the recession curve …

Tc is computed by summing all the travel times for consecutive compo-nents of the drainage conveyance system. Tc influences the shape and peak of the runoff hydrograph. Urbanization …

The spatial representation of travel time can be transformed into a cumulative distribution plot detailing how travel times are distributed throughout the area of the watershed.

The CivilWeb Rainfall & Runoff Calculator package includes a free Time of Concentration calculator tool which can be used to evaluate the time of concentration for a catchment using a variety of different …

There are many methods available to estimate the time of concentration including the Kirpich formula, Kerby formula, NRCS Velocity Method, and NRCS Lag Method. The NRCS Velocity and Lag …

Jul 5, 2025 · Calculate time of concentration using Kirpich, NRCS, and Manning methods. Ideal for stormwater design and watershed hydrology. Fast, accurate, free.

Free time of concentration calculator for small watersheds. Compute Tc using Kirpich, NRCS TR‑55 sheet/shallow/stream flow, FAA, Kerby, and user‑defined velocity methods with step‑by‑step formulas.

Describes several methods and equations useful for time of concentration computations.

RATE INTENSITY FREQUENCY CURVE Rate of Rainfall in Inches Per Hour, To Be Expected Once In The Number Of Years Indicated For Periods Of Time From Five Minutes To One And One-Half …