Composite modeling to design a complex dam spillway

Sébastien Erpicum, Benjamin Dewals, Pierre Archambeau, Michel Pirotton

Friday 3 july 2015

9:30 - 9:45h at Asia (level 0)

Themes: (T) Water engineering, (ST) River and coastal engineering

Parallel session: 14C. Engineering - Industrial

Physical modeling and numerical modeling are two efficient analysis approaches in hydraulic engineering. The interactive application of both methods is probably the most effective response to varied flow problems analysis. The paper presents in details the application of a composite modeling approach to the design of a complex dam spillway. The structure is made of three gated bays on the top of a broad crested weir on the left bank of a valley. The gates discharge in a channel with a limited bottom slope and a variable width. Depending on the discharge through the weir, the control section may shift from the weir crest to the channel. A recent update in the dam’s hydrology showed that an increase of the spillway discharge capacity is required to maintain the dam safety level. In order to assess the discharge capacity of the existing works and to design and validate rehabilitation solutions, a composite modeling approach has been applied. First, a physical scale model of the existing works has been built and operated. It enabled to define very accurately the existing discharge capacity and to validate a numerical model of the system. Second, the numerical model has been used to rapidly test several rehabilitation solutions. Finally, the final rehabilitation solution has been validated and optimized using the physical model. In conclusion, the paper shows how composite modeling enables to combine the inherent advantages of physical and numerical modeling approaches, which are complementary, while being beneficial to the delay as well as the quality of the analysis.