Ensuring spillway discharge capacity in case of reservoir floating debris
2011 (English)Conference paper (Refereed)
Reservoir floating debris can clog up the spillway and constitutes, during extreme floods, a potential danger to dam safety. Efforts must be made to mitigate the reduction in the spillway discharge capacity, especially for dams with only two or three spillway openings, as is often the case in Sweden. In connection with the upgrade of a dam, two countermeasures are examined in hydraulic model studies, i.e. a debris visor and an overflow debris weir. A total of 100 small pine trees with roots are used, with a density varying between 650-1000 m3/s and corresponding prototype lengths varying between 15-25 m. The visor is placed obliquely upstream of the spillway where the water depth is 8-10 m. The visor stops effectively the debris. Trees with low density approach the visor afloat and are intercepted in the surface water. Debris with higher density is dragged down when approaching the visor. As a result, it covers the visor height, leading to a reduction in the flow passage. For the overflow weir, if the weir water depth exceeds certain limit, solitary trees or a few trees knitted together can pass the weir without much difficulty. However, for the weir water depth allowed (less than 3 m), if clogging up along the weir starting from the existing spillway and extending upstream, the debris would get wedged and remain on the weir. As a result, the overflow capacity would be restricted, which limits the use of such a fixed weir as countermeasure against debris.
Place, publisher, year, edition, pages
IdentifiersURN: urn:nbn:se:kth:diva-179765OAI: oai:DiVA.org:kth-179765DiVA: diva2:889420
11th Int. Conf. Fluid Control, Measurements & Visualization, Dec 2011, Keelung, Taiwan
QC 201601072015-12-242015-12-242016-01-07Bibliographically approved