Runoff Coefficient For Roof

Runoff coefficient c this coefficient allows for the quantity of water which runoff a particular type of surfacing into a drainage system and discount the quantity of water which will soak into or through the surfacing.

Runoff coefficient for roof.

Typical values are given below. Step 1 determine the footprint of your structure f in square feet. Runoff coefficients paired rainfall p and observed runoff q obs from 21 living roofs volumetric runoff coefficient for each storm linear regression for paired p. Annual runoff generated roof area annual rainfall runoff coefficient 200 1000 0 9 180 000 litres or 47 520 gallons hence a storage capacity of 47 520 gallons is required to sail through the summer months with adequate water supply.

The runoff coefficient c is a dimensionless coefficient relating the amount of runoff to the amount of precipitation received. There are two ways you can find the runoff coefficient. The runoff coefficient describes the percentage of rainfall which runs off a particular surface during a storm event. Tot per per tot imp impa a c a a.

Count the number of downspouts coming from your roof. A runoff coefficient is a number that relates the rainfall rate and runoff rate. Why is it important. The formula for calculating this flow is called the maming formula.

1 predicted c v must increase or remain constant for 0 p 100 mm 2 predicted c v 1 for 0 p 100. Measure along the length of the house or building and along the width of the house or building in feet. Divide 100 by the number of downspouts in order to obtain the percentage of water collected from each downspout. And q the peak storm water runoff rate due to a storm of intensity i on.

One of the parameters in the rational method equation q cia is the runoff coefficient c. Rational method runoff coefficient applications. The american society of plumbing engineers data book suggests that initially there will be some friction along the drainage path but it will quickly go to zero. The other parameters are a the area of a watershed.

It is possible to calculate the average runoff coefficient for non homogeneous areas considering. I the design rainfall intensity for a storm of specified recurrence interval and duration equal to the watershed time of concentration. C v using datafit 9 1 32 model selection criteria. It is a larger value for areas with low infiltration and high runoff pavement steep gradient and lower for permeable well vegetated areas forest flat land.

Multiply the two figures together to obtain the square footage of your roof step 2 determine the percentage of water collected from each downspout p. Rational method runoff coefficients. Using the runoff coefficient scientists and hydrologists can calculate how much water passes over a given area per second.