Here is another perspective ...

Here is another perspective by Steven Trinkaus, from the US, and the world leader in Low Impact Technology. @ Kae Man Man, My name is Steve Trinkaus. I am an engineer in Connecticut (US). I am doing some consulting for Pusan National University and Land & Housing Institute on Low Impact Development in South Korea. I have made several presentation on LID in South Korea over the past year and will be returning to South Korea in October 2014 to present at the IWA conference. Maybe we can meet up at that time. Regarding your particular problem, Hydrocad is a much simply hydrology program to model the watershed with the appropriate soil type and vegetative cover which will give you peak rate and runoff volume for the desired design storm events. It does not require rainfall data, temperature data to run. You simply need to know the design rainfall amount for each design storm. As an example, when I live the 2-yr rainfall event is 3.3” per 24 hours. The time of concentration is based upon the land cover and slope of the land and is comprised of several components: overland flow, shallow concentrated flow, open channel flow, and pipe flow. If you would like to discuss further, please contact directly at strinkaus@earthlink.net. Hope to hear from you. Best Regards, Steve