The Rainfall-Runoff Calculator is a valuable tool for estimating the peak runoff from a specific area during a storm event. This tool is based on the Rational Method, which is widely used in hydrology and civil engineering. Let’s delve into what the Rainfall-Runoff Calculator does and how it works.
The Formula
The Rational Method employs a simple formula to calculate peak runoff:
Q = CiA
Where:
- Q represents the peak runoff rate, measured in cubic meters per second (m³/s).
- C is the runoff coefficient, a dimensionless factor that depends on various factors such as land use, soil type, and vegetation.
- i signifies the rainfall intensity, typically measured in meters per second (m/s).
- A stands for the drainage area, measured in square meters (m²).
This formula is fundamental in determining the rate at which rainwater flows off a specific area, which is crucial for urban planning, flood control, and infrastructure design.
Example of Rainfall-Runoff Calculator
Let’s illustrate how to use the Rainfall-Runoff Calculator with an example. Suppose we have an urban area with a drainage area (A) of 500 square meters, a runoff coefficient (C) of 0.7, and a rainfall intensity (i) of 0.05 m/s. Plugging these values into the formula:
Q = 0.7 x 0.05 x 500 = 17.5 m³/s
So, the peak runoff rate for this specific urban area during the given storm event is 17.5 cubic meters per second.
Most Common FAQs
A1: The runoff coefficient depends on various factors, including land use and soil type. You can find tables and guidelines from hydrology references or local authorities to help estimate C for your area.
A2: Rainfall intensity can vary significantly by location and storm type. You can check historical weather data or consult local meteorological sources to get an idea of typical values.
A3: Yes, the calculator can be used for both small and large-scale projects, as long as you input accurate data for C, i, and A.
