Hello! The requested citation for the IMD Empirical Reduction Formula is as follows:

Pt = P24(t/24)1/3

Runoff Computation in a Data Scarce Environment for Urban Stormwater Management. A Case Study

(RATHNAM et al., 2001)

https://jglobal.jst.go.jp/en/detail?JGLOBAL_ID=200902132954714867&rel=0

Thanks for your answer C. Mei-Ling Hamilton , but in that paper also, they have used that formula . I am looking for source citation .

Hello again! Perhaps the following citation might be of more interest:

Ramaseshan, S., “Urban Hydrology in Different Climatic Conditions”, Lecture notes of the 5th International Course on Urban Drainage in Developing Countries", Regional Engineering College, Warangal, India; 1996.

Thanks for your answer C. Mei-Ling Hamilton. May I get that copy online or need to find somewhere offline??

Hello! Perhaps it might be possible to contact Dr. S. RAMASESHAN directly. His email addresses are listed under No. 26 on the “Former Faculty” page of the Civil Engineering Department at IIT Kampur:

https://www.iitk.ac.in/ce/former-faculty

Thanks for your reply again C. Mei-Ling Hamilton . this helps a lot. I will put a mail to him.