Rainfall units conversion from depth to rate/intensity

Asked by: Tracey White

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.

How do you convert rainfall depth to intensity?

To convert a rainfall depth during a period of time into an intensity in mm/hr. The depth in mm is divided by the duration in hours : ie: 50 mm over 30 minutes. => 50 / 0.5 = 100 mm/hr.

How do you calculate rainfall intensity?

A similar exercise can be done for T1 = 20min and T2 = 60min. Once this is done, the equation we will have two equations relating time to precipitation for the specific MSP. Then, I = P/T*60 can be used to determine the rainfall intensity “I” for any time of concentration “T” between 5 and 60 minutes.

What is the unit of intensity of rainfall?

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 depth?

Here’s what you’ll need to do:

1. Measure the diameter of the bucket at the level of the rain. …
2. Measure the diameter of the bucket at the bottom in the same way.
3. Calculate the average of the two diameters.
4. Divide by two to find the average radius.
5. Find the average volume of rain = Depth x radius x radius x 3.14.

How do you read a rainfall intensity chart?

Quote from video: So let's take a look at the chart. We have rainfall intensity in inches per hour versus rainfall duration in hours and you can see that we have these lines representing at 10 25 50 and 100 year storm.

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.

What does 10 mm rainfall mean?

Heavy rain: Greater than 4 mm per hour, but less than 8 mm per hour. Very heavy rain: Greater than 8 mm per hour. Slight shower: Less than 2 mm per hour. Moderate shower: Greater than 2 mm, but less than 10 mm per hour. Heavy shower: Greater than 10 mm per hour, but less than 50 mm per hour.

How do you calculate rainfall in mm?

Instruments. The standard instrument for the measurement of rainfall is the 203mm (8 inch) rain gauge. This is essentially a circular funnel with a diameter of 203mm which collects the rain into a graduated and calibrated cylinder. The measuring cylinder can record up to 25mm of precipitation.

How do you calculate rainfall in mm per hour?

Violent rain: If 2” of rain have fallen in 10 minutes, then the equivalent rainfall rate in terms of in/hr will be 60 min / 10 min * 2” of rain = 12 in/hr. Heavy rain: If 15 mm of rain have fallen in 30 minutes, then the equivalent rain rate in terms of mm/hr will be 60 min / 30 min * 15 mm of rain = 30 mm/hr.

What does 1 mm rain mean?

However, 1 mm of rain refers to the “depth” of rain that would be received in 1 meter² (m²) or a square of one metre in length and width. So 1 mm of rain translates to 1 litre of water in a single metre square.

Why is rainfall measured in mm?

The reason the rain is reported in millimeters or inches is that a regular rain shower usually deposits a quantity of water most suited to such measurement. For example, a typical rain storm will not deposit a meter of water except in extreme storm situations like a hurricane.

What is rainfall depth?

The precipitation depth indicates to what depth liquid precipitation would cover a horizontal surface in an observation period if nothing could drain, evaporate or percolate from this surface. The precipitation depth of 1 mm corresponds to a liquid quantity of 1 litre to 1 m² of ground area.

What is term is used for a plot of rainfall intensity?

A hyetograph is a graphical representation of the distribution of rainfall intensity over time.

What are the three classification and intensity of rainfall?

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. Heavy rain — when the precipitation rate is > 7.6 mm (0.30 in) per hour, or between 10 mm (0.39 in) and 50 mm (2.0 in) per

Why is rainfall intensity measured in units of depth over time and not volume over time?

Quote from video: Похожие запросы

What is Horton’s equation?

The original Horton equation was given as follows. (1) f ( t ) = f c + ( f 0 – f c ) e – k t where f₀ is the initial value of infiltration capacity (mm/h) at the beginning of rainfall; k is the soil-specific decay constant.

What is rainfall depth?

The precipitation depth indicates to what depth liquid precipitation would cover a horizontal surface in an observation period if nothing could drain, evaporate or percolate from this surface. The precipitation depth of 1 mm corresponds to a liquid quantity of 1 litre to 1 m² of ground area.

How do you convert annual rainfall to mm HR?

So if you had 600 mm monthly average RF in May with 20 rainy days and 11 dry days, take 600 mm/(20 days * 24 hours) = 0.8 mm/hour average monthly RF intensity. If the rainfall is 20 mm, then multiply the volume by 20.

What do you mean by Hyetograph?

Definition of ‘hyetograph’



1. a chart showing the distribution of rainfall of a particular area, usually throughout a year. 2. a self-recording rain gauge.

What is the unit of hyetograph?

Unit hydrograph is a direct runoff hydrograph resulting from one unit (one inch or one cm) of constant intensity uniform rainfall occurring over the entire watershed. The concept of unit hydrograph is based on linear systems theory and follow the principles of superposition and proportionality.

What is hyetograph in rainfall?

(a) Hyetograph: A hyetograph is a plot of the average intensity of rainfall against the time interval. The hyetograph is derived from the mass curve and is usually represented as a bar chart. The area under a hyetograph represents the total precipitation received in the period.