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Learn the rational, curve number and SCS methods for calculating runoff from rainfall for different land use and soil conditions. See examples, formulas, tables and diagrams for each method.
RUNOFF CALCULATIONS . 1. To estimate the magnitude of a flood peak the following alternative methods are available: 2. Unit-hydrograph technique 3. Empirical method Semi-Empirical method (such rational method). 1. There many empirical or Semi-Empirical formulae used to estimate the runoff discharge from catchment area.
Dec 28, 2020 · When calculating roof runoff volume, you can use a direct runoff formula (in in 3) which calls for multiplying the area that covers the roof by the inches of rainfall. More nuanced, complicated equations take into account factors such as variations in how much rain a storm creates over time.
The most common means for determining runoff for minor hydraulic structures is the rational formula: Eq. 1 Q = C · I · A. Where: Q = peak discharge, ft 3 /s (m 3 /s) C = runoff coefficient = percentage of rain that appears as direct runoff I = rainfall intensity, in/h (mm/h) A = drainage area, acres (m 2)
Jan 7, 2024 · The runoff calculator simplifies this process, providing an efficient means to determine the runoff volume. In this article, we’ll explore how to use the calculator, the underlying formula, an example scenario, frequently asked questions (FAQs), and a concluding overview.
It is useful in estimating runoff on relatively small areas such as roof tops and parking lots. Use of the rational equation should be limited to drainage areas less than 20 acres (Amer. Public Works Assn., 1974) with generally uniform cover type and grade. Required output = peak discharge only.
Dec 12, 2023 · EPA’s National Stormwater Calculator (SWC) is a software application tool that estimates the annual amount of rainwater and frequency of runoff from a specific site using green infrastructure as low impact development controls.
