The Washout Mechanism of the Niedów Dam and its Impact on the Parameters of the Flood Wave

Abstract

On 07 August 2010 a disaster occurred at the barrage Niedów located on the river Witka as a result of unprecedented rainfall in the Nysa Luzycka catchment area. The flood wave swept through the dam crest destroying almost the whole structure within a few dozen minutes. The only element that did not vanish was the concrete structure of the spillway and water-power station. The process of dam breach is not so far completely resolved and reliable predictive models of dam breaching are still challenging problem. Modelling of the process requires an evaluation of parameters affecting this phenomenon, namely, the breach size and the timescales for the breach formation. The latter is particularly important for characterizing the outflow hydrograph and, consequently, for the assessment of the damage risk of areas below the dam. The paper presents a mechanism of breaching of the Niedów dam which consists of three stages: the downstream slope wash out, the breaking down of the dam crest and the damaging of upstream slope revetments. The comparison of breach parameters with that evaluated based on several empirical formulas and numerical modelling is also presented.

Combined Influence of Terrain Modell and Roughness in Dam Break Wave Simulation

“…Knowing the advantages and disadvantages of these models regarding dam break inundation simulation and the uncertainties the results possess helps to predict potential dam break flood extent. The uncertainty of the model result origins from uncertain breach outflow [4], simplified representation of the valley topography by cross sections (1D-model) or a computation mesh (2D) and simplifications in the hydrodynamic solution. Manning's roughness is an important parameter for the more common 1D and 2D models.…”

Interaction between hydraulic conditions and structures – fluid structure interaction problem solving. A case study of a hydraulic structure

“…A sample FSI analysis was carried out using a model of the Niedów dam which was destroyed in the disaster of 7 August 2010. This dam break on the Witka River resulted from a limited flow capacity due to erroneous settings of limit switches, preventing the full opening of the dam Tainter gates [6][7][8].…”

Numerical and physical modeling of water flow over the ogee weir of the new Niedów barrage

“…The low-head barrage structure consisted of two lateral earth dikes to elevate the headwater, as well as a three-span ogee weir with tainter gates. The two earth composite dikes had an overall height of 11.6 m, a top width of 5.0 m, an upstream slope of 1:3 covered by concrete slabs and , 2010, after a sudden and extremely high rainfall in the region of Niedów, Radomierzyce and Bogatynia, the reservoir exceeded its capacity of 5.6 million m 3 , causing both earth dikes to fail due the water overflow (Kostecki and Redowicz, 2014). This situation provoked the destruction of both lateral earth dikes of this low-head barrage.…”