How do you calculate average rainfall intensity?

How do you calculate average rainfall intensity?

The first thing that you have to do is to convert the table of annual maximum (statistical) values of rainfall depth into Intensity Values (mm/hr) just divide the total depth (precipitation) by the rainfall duration (i.e. for 1971 during 1 hr you have a rainfall max.

How is peak discharge calculated?

The Rational Formula is expressed as Q = CiA where: Q =Peak rate of runoff in cubic feet per second C =Runoff coefficient, an empirical coefficient representing a relationship between rainfall and runoff.

How do you calculate rainfall intensity in Excel?

The Excel formulas in the spreadsheet are set up to calculate the constants, a and b, in the equation i = a/( d + b ), by linear regression of 1/i vs d. Then the design rainfall intensity is calculated with the equation i = a/( d + b ) using the calculated values for a and b.

How do you calculate rainfall?

Find the average volume of rain = Depth x radius x radius x 3.14. Find the area at the top of the bucket (this is the area over which the rain is collected). Divide the rainfall volume by this area to get the rainfall.

How do you calculate rainfall deviation?

Meteorologists do this by computing the Coefficient of Variation. The Coefficient Variation is simply the standard deviation divided by the average annual rainfall. For San Francisco’s average rainfall of 21.79″ for its period of record, the standard deviation is 7.63″. Dividing 7.63 by 21.79 gives 0.35.

What is peak rainfall?

Peak rainfall – maximum amount of rainfall (millimetres). Lag time – the time taken between peak rainfall and peak discharge. Rising limb – shows the increase in discharge on a hydrograph.

How is rainfall discharge calculated?

Find out the peak storm discharge by the Rational Method assuming that the rainfall in 5 hours is 20 cm. What will be the peak discharge if the catchment area is of clayey soil lightly covered or of steep but wooded rock? Q = 0.028 PfIcA = 0.028 x 0.10 x 0.60 x 2.98 x 80,000 = 400 cum/sec.

How do you convert rainfall depth to intensity?

In order to have the average rainfall intensity in m/s corresponding to that interval of time, you have to divide the rainfall depth for the number of seconds in the time interval or for mm/s you multiply for 1000/21600. If you want the intensity in m/h you divide for 6 hours.

What is the rainfall intensity?

Rainfall intensity is defined as the ratio of the total amount of rain (rainfall depth) falling during a given period to the duration of the period It is expressed in depth units per unit time, usually as mm per hour (mm/h).

How do you calculate rainfall intensity?

In summary, rainfall intensity is calculated by dividing the amount of rain accumulated by the period of time during which this happens. Rainfall intensity is to rainfall amount what speed is to the distance traveled in a mechanical analogue.

How to calculate runoff coefficient?

The Run-off Coefficient when Run-off is Given calculates the value of runoff coefficient when we have prior information of other parameters used is calculated using runoff_coefficient = Runoff depth / Rainfall depth . To calculate Run-off Coefficient when Run-off is Given, you need Runoff depth (R) and Rainfall depth (P).

What is design rainfall intensity?

Rainfall Intensity. Because the rainfall intensity/duration relationship is assessed by assuming that the duration is equal to the time of concentration, small areas with exceedingly short times of concentration could result in design rainfall intensities that are unrealistically high. To minimize this likelihood,…

What is precipitation intensity?

Rainfall intensity is classified according to the rate of precipitation, which depends on the considered time: Light rain — when the precipitation rate is < 2.5 mm (0.098 in) per hour. Moderate rain — when the precipitation rate is between 2.5 mm (0.098 in) – 7.6 mm (0.30 in) or 10 mm (0.39 in) per hour.