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— Rainfall Intensity from IDF Curve

Design rainfall intensity from fitted intensity–duration–frequency coefficients, in either the Sherman form i = a/(t_d+b)^c or the Bernard form i = a·T^m/(t_d+b)^c. Coefficient units set the output units.

Solution

History

Sources:
[1] L. K. Sherman, "Maximum rates of rainfall at Chicago," Trans. ASCE, vol. 95, no. 1, pp. 951–960, 1931.
[2] M. M. Bernard, "Formulas for rainfall intensities of long duration," Trans. ASCE, vol. 96, no. 1, pp. 592–606, 1932.
[3] V. T. Chow, D. R. Maidment, and L. W. Mays, Applied Hydrology, 2nd ed. New York, NY, USA: McGraw-Hill Education, 2013.
[4] Precipitation-Frequency Atlas of the United States, NOAA Atlas 14. Silver Spring, MD, USA: National Oceanic and Atmospheric Administration.

Reference content only — not a substitute for professional engineering judgment. Verify all values, tolerances, and specifications against current official standards before use in production or safety-critical work. Provided without warranty of accuracy or fitness for any purpose.