Coping with Uncertainty in the Design of Hydraulic Structures: Climae Change is But One More Uncertain Parameter

The design of hydraulic structures is based on parameters which are known with a variable degree of uncertainty; some of them are time-variant and follow trends. River inflow is a major parameter for hydraulic structure design; it is known to vary on a seasonal and annual basis. Until recently, it was assumed to be relatively stable on the long term. This parameter is now affected by climate change; as result river flow now follows long term trends; however, the magnitude of those trends is difficult to establish. This adds to the uncertainty in the design of hydraulic structures. Coping with this new source of uncertainty may be achieved in the same way most of the other uncertain time-variable parameters are dealt with: the structures are designed for conditions anticipated to prevail in the mid-future, 15 to 20 years after commissioning, leaving the possibility for adjustments after a few years of operation, when the trends are quantified with less uncertainty.