http://www.sciencedirect.com/science/article/pii/S1674987115001255

i will help you in calculating R

You could use linear regression analysis in finding for I30 then make find it for I20

Eyad Abushandi unfortunately I haven't got information about I30. Only 3-hours precipitation, mean annual I20 and rainfall intensity from https://pmm.nasa.gov/data-access/downloads/gpm

That's why my question was about existing formulas of R calculation based on rainfall intensity of different time scales

R factor of each rainfall event is calculated as the product of total storm energy(E) and maximum 30 min intensity (I30) of that rainfall event. R factor of each rainfall events are summed up and divided by number of years to get average annual R factor values.

For Detailed method, you can see my article regarding how it is calculated in detail.

We can even use the web based erosivity module( WERM) to automatically calculate R factor considering I30 using 10 minute interval rainfall data.

http://www.envsys.co.kr/~werm/

Article Application of Web ERosivity Module (WERM) for estimation of...

Dear Avay Risal , have you got any idea where I can get 10-min rainfall data?

10 minute interval data can be obtained from meteorological centres of your country /locality. Depending upon the country's national or regional data collection and distribution policy, you can purchase the data or get it for free from those meteorological centre.

In case of South Korea, those data can be obtained for free from the website of KOREAN METEOROLOGICAL ASSOCIATION( KMA)

http://www.kma.go.kr/weather/observation/aws_table_popup.jsp

Dear Avay Risal, Can you please tell me, how to calculate R- factor?

I have rainfall data for my catchment area, past 30 years. How to distinguish or identify I20 or I 30 rainfall data?

Interesting question !

Dear Meena,

The first task for calculation of the R factor is to separate rainfall event from long-term rainfall dataset. Following criteria must be considered for identification of erosive rainfall event.

(i) Storm period with less than 1.3 mm over six hours is used as a divider of a rainfall event

(ii) The rainfall event having less than 12.7 mm of amount is excluded in R factor calculation assuming insignificant rainfall to cause soil erosion unless there is 6.25 mm rainfall in 15 min.

After that,

product of kinetic energy and maximum 30 min intensity of each rainfall event is calculated to get erosivity of each event.

Then, R factor of each rainfall events are summed up and divided by number of years to get average annual R factor values.

For Detailed method, you can see my article .

Article Application of Web ERosivity Module (WERM) for estimation of...

Hello Avay Risal .. I have daily rainfall data (CFSR data ) but don't have I30

or I20 . Is it possible to calculate the R using WERM??

Kindly give your suggestions..

WERM uses 10 minute intervall rainfall data to calculate erosivity factor.So you cannot calculate R factor accurately using daily data.. But you can estimate it using existing regression models for your area if available.

Thank You so much Avay Risal ..

Is there any method to convert daily data to 10 minute interval rainfall data..??

R = 1, 038 (10) −3 Pa P1h−2ans P24h−2ans

R = érosivité potentielle annuelle (MJ mm ha--1 h --1 an--1)

Pa = précipitation moyenne annuelle (mm)

Plh--2ans = précipitation d’une durée de une heure et de 2 ans de récurrence (mm)

P24h--2ans = précipitation d’une durée de 24 heures et de 2 ans de récurrence (mm)

To calculate I20 there are few formula that u dan use . As for me i choose to use them formula that suggest buat department of irrigation Malaysia.You can refer to MSMA 2nd edition under chapter Rainfall Design

Hello Anatolii,

I sugget you this paper:

Rainfall erosivity estimation based on rainfall data collected over a range of temporal resolutions

https://www.hydrol-earth-syst-sci.net/19/4113/2015/hess-19-4113-2015.html

Kinds regards

Mourad GUESRI

Article RainfallErosivityFactor: An R package for rainfall erosivity...

Maybe it helps.

Go through-

Article A Review of RUSLE Model

I don't know why you don't want to use empirical formulas if some have already been developed and validated for your region. Almost all RUSLE studies use these empirical equations since rainfall intensity and duration data are hard to come by.