Welcome to the Rainwater Runoff Calculation Tool! This tool helps you calculate how much rainwater will run off different types of surfaces. This is important for designing good drainage systems, preventing floods, and managing stormwater in cities and towns.

The tool asks for the area of different surfaces like concrete, asphalt, gravel, soil, and grass. Each type of surface has a different ability to absorb or let rainwater flow off. By entering the area of each surface and the rainfall intensity, the tool will calculate the total amount of rainwater by using the Rational formula that will flow off in cubic meters per second.

Stormwater Runoff in  m³ / sec                     Q             =             C*I*A / 3.6 *10⁶  

Here;                                                                                                                                    

C             Runoff coefficient                                                                                                                          

I               Rainfall intensity in mm/hr                                                                                                                          

A             Catchment area in m²   

A is divided into these five categories:

Concrete paved area(A1)

Asphaltic paved area(A2)

Gravel paved area(A3)

Unpaved soil area(A4)

Grassy area (A5)

This tool is easy to use and helps you quickly estimate how much rainwater runoff you can expect. You can choose the units you prefer (square meters, hectares, or acres), and enter the rainfall intensity to get your results.