Thursday July 26, 2012
Total attendance - 35. Scarborough Chapter members - 27, Other Chapter Members - 2, Chapter volunteers - 4, Guest - 2



By Ranendra Ponrajah, P.Eng., Ph.D. - Ontario Power Generation

The well attended presentation started off on time with light refreshments. Madu, started with a chronological review of floods from 1957 to present spanning many continents. He started off with anecdotal definitions of floods, leading the audience to the complex theories behind estimating the peak discharge due to a flash-flood event. He explained the different meanings of the term “100-year flood”, and how this is interpreted by municipal engineers focused on small catchments as opposed to others focused on large catchments. Methods underlying hydrometric data collection and analysis was explained and Madu, in his classic anecdotal style, explained why it is important to validate the data prior to using it.

Madu explained in simple terms, without losing the engineering essence, the role played by engineering assumptions in profiling the post-event flood-discharge. As proof of concept, he produced two design guides, one originating from his work in Sri Lanka, and the other originating from his work in Malaysia. He also acknowledged gratefully the contribution of others in the development of these guidelines. He highlighted the values these guidelines are providing even today, after more than 30years since first publication.

The concepts of intensity & duration of a flood event were well explained with practical examples derived from Madu’s experience spanning over 50-years in Sri Lanka, Malaysia, Indonesia, U.S.A. and Canada. He cautioned on the use of pre-packaged programs, without fully understanding the principles underlying the programs (software). This was further corroborated by a member from the audience.

The presentation concluded with very valuable insights into the cause and effect of basement flooding – a topic of interest to most of us. Many valuable tips were provided on how a homeowner can protect their basement from flooding with simple inexpensive solutions.

The presentation concluded on time with Madu responding to many questions from the audience.


When 6:00 p.m. to 8:15 p.m. - Jul 26, 2012 (Thursday)
Where Bendale Public Library Meeting Room,
1515 Danforth Road, Scarborough
(Intersection - Lawrence E/McCowan)
Map Google Maps icon
Registration To register for this seminar, please click on link below

First come first served. Priority will be given to Scarborough Chapter members, then other PEO members, guests and friends.

Any questions - please contact

Cost Sponsored by Scarborough Chapter
Scarborough Chapter members: No charge
PEO members: No charge
Guests and others: No charge
Light refreshments and snacks will be served.

About the Seminar

Floods and Flash Floods: Mitigation measures.

Floods and Flash floods have been known to humans from time immemorial. Understanding them and trying to reduce their impact has been very recent. The presenter will outline his experience from 1964 in Sri Lanka, U.S.A., Malaysia, Indonesia and Canada of how flood studies had developed over the years; the different types of flood hydrographs that has evolved; the rainfall patterns of flood causing storms; and the use of Intensity-Duration-Frequency (IDF) curves.

The presentation standard will be to a general audience of all disciplines of engineers and students.


•Explain the rainfall patterns, hyetographs, hydrographs, catchment areas (watersheds), what causes floods and what causes flash floods

•A look at the historic floods and the regulatory storms in Ontario: Hurricane Hazel: 1954 in Toronto, and Timmins Storm: 1961 in Timmins, about 700 km North of Toronto.

•Statistical Methods, Frequency Analysis and Return Periods

•Rational Method and Modified Rational Method for small catchments

•Use of retention and detention in mitigating floods

•Flood mitigation costs vs. risks and loss or damage to life and property

•Use of computers and the future of flood mitigation methods.

Guest Speaker:

N. Madusuthanan (Madu), P. Eng.

maduMadu has extensive work experience from 1964 in Sri Lanka, U.S.A., Malaysia, Indonesia and Canada on Irrigation, Drainage and Flood Mitigation Projects. His interest and knowledge of Floods and Flash Floods has helped in preparation of a Hydrological Design Standard in Malaysia in 1977 and a Design Standard in Sri Lanka in 1982. In 1982 he wrote a computer program in Basic Language for flood studies complying with the new standard which facilitated design of more than 30 projects a day, each of which would have normally taken many days by using manual methods or calculators. This successfully completed design of 500 rehabilitation projects under a World Bank Funded Programme on time. He is very familiar with Computer applications and voluntarily trained the staff in Sri Lanka and Indonesia; retired in 1990 as Senior Deputy Director of Irrigation, Sri Lanka; received his P. Eng. license in 1999; worked on contract with various companies in Toronto and has good familiarity with the Standards and Methods used in Ontario and Canada. He also works part-time as a Computer Instructor at ACCES, Scarborough.

He is an active volunteer and Executive in the Scarborough Chapter of PEO.