Authors: C.R. Donnelly & R.D. Zhou
Canadian Dam Association 2009 Conference, October 6, 2009
Abstract
In any dam safety assessment, it is necessary to establish the inflow design flood (IDF) to ensure that the dam has adequate
capacity to handle flood flows up to a point where there is no unacceptable risk to the public if the dam should fail. In
Ontario, and many other areas in Canada and USA, the inflow design flood may be generated either by high intensity
summer storm events or, more commonly, by rain on snowmelt (or simply snowmelt) events depending on the size and
location of watershed, local meteorological conditions and other hydrological parameters. In order to determine the critical
flood generating mechanism for a dam site, a detailed hydrological model is usually needed in order to simulate both types
of flood events. Based on the simulation model, the higher flood generated is selected as the inflow design flood. This
procedure can require a significant amount of effort and, therefore, cost.
This paper provides details of a simple, but effective, methodology based on hydrological principles commonly used in dam
safety assessments to accurately identify the critical flood generating mechanism for a given dam site using watershed and
local meteorological characteristics without going through the detailed hydrological modeling processes. This procedure
will allow hydrologists and hydro-technical engineers to focus on the evaluation of the critical flood generating events
leading to reduced time and efforts in the performance of hydrological analyses of accurate and reliable dam safety
assessments.
