A runoff coefficient is a number that relates the rainfall rate and runoff rate.
Runoff coefficient metal roof.
Also outlined are the steps to build your own rain barrel to collect water from your roof and downspout for all outdoor uses like watering and cleaning.
For sample purposes a 55 gallon barrel will be used.
For example it is 0 9 for metal or tile roofs and up to 0 3 for green roofs.
One of the parameters in the rational method equation q cia is the runoff coefficient c.
The runoff coefficient value is an attempt to take account of the volume of runoff which is absorbed into the surface.
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.
Precipitation and runoff data from each event were used to calculate the runoff coefficients for the roofs based on the same definition as in equation which means that the runoff coefficients for the field cases were calculated as the runoff volume over the total precipitation volume for the time span covered by the precipitation event.
Unless the zinc content is particularly high it is safe to use on lawns and ornamental gardens.
This is not a very precise variable and as such attempts have been made to remove it using statistical analysis of historical events.
Why is it important.
This coefficient accounts for the fact that some roof surfaces are more efficient than others at collecting rainwater.
Use it to wash cars and outdoor equipment and to rinse patios.
The system outlined below will walk you through the steps of determining your rain barrel sizes based on average roof runoff.
The runoff coefficient c is a dimensionless coefficient relating the amount of runoff to the amount of precipitation received.
For example a pitched metal roof is typically the most efficient.
I the design rainfall intensity for a storm of specified recurrence interval and duration equal to the watershed time of concentration.
Runoff generated roof area peak rainfall runoff coefficient 200 150 0 9 7100 gallons.
There are two ways you can find the runoff coefficient.
Alternatively the runoff coefficient is the factor by which depending on the type of surface the effective impermeable area is calculated.
This makes the duration different for all the events as it is based on the actual duration of the event.
One is by using the rational method and the other is by using a runoff coefficient.
Roof runoff has many outdoor uses.
Runoff coefficients when calculating the amount of runoff that can be harvested from a roof it is common to include a runoff coefficient.
Using the runoff coefficient scientists and hydrologists can calculate how much water passes over a given area per second.
And q the peak storm water runoff rate due to a storm of intensity i on.
We can observe that there is a significant reduction in storage capacity compared to the first scenario.
