Distorted Physical Model to Study Sudden Partial Dam Break Flows in an Urban Area

Abstract

A distorted physical model, based on Ürkmez Dam in Izmir, Turkey, was built to study sudden partial dam break flows. The distorted model had a horizontal scale of 1=150 and a vertical scale of 1=30, containing dam reservoir, dam body, and downstream area-from dam body to Ürkmez urban area until the sea coast. In the model, the reservoir is approximately 12 m 3 , the dam body has a width of 2.84 m and a height of 1.07 m, and the downstream area is nearly 200 m 2 . The Ürkmez Dam was chosen because Ürkmez Town is located right at its downstream area, allowing the study of dam break flows in an urban area. Furthermore, the dimensions were suitable such that it allowed the construction of a physical model (dam reservoir, dam body, and downstream area) having a horizontal scale of 1=150 in the available space of 300 m 2 . The features creating roughness such as buildings, bridge, and roads were also reflected in the physical model. The dam break flow was investigated for sudden partial collapse, which was simulated by a trapezoidal breach on the dam body. The water depths at downstream area were measured at eight different locations by using eþ WATER L (level) sensors. The velocities were measured at four different locations by ultrasonic velocity profiler (UVP) transducers. The propagation of the flood was recorded by a high-defnition camera. The experimental results show that the Ürkmez area can be flooded in a matter of minutes, at depths reaching up to 3 m in residential areas in 4 min. The flood wave front can reach the residential areas in 2 min and to the sea coast in 4 min. Flow velocities can reach 70.9 km=h in sparse residential areas, close to dam body. Away from the dam body in the sparse buildings part of the town, the velocities can reach 27.7 km=h. In dense residential areas of the town, the velocities are too low (2.8 km=h) but flow depths can reach 3 m. Velocity profiles show similar behavior like unsteady and nonuniform open channel flow in nonresidential areas close to the dam body. In residential areas away from the dam body, the velocity profiles are more uniform, having lower velocity values. Vertical variations of velocities show markedly different behavior during rising and recession stages. The profiles are smooth during the rising stage in sparse residential area, yet it shows fluctuating behavior during the recession stage.

Two-dimensional numerical modeling of flood wave propagation in an urban area due to Ürkmez dam-break, İzmir, Turkey

“…The performance of the two-dimensional numerical model was tested by comparing the numerically calculated flow depth hydrographs with the flow depth hydrographs measured in the downstream area of the distorted physical model of Ü rkmez Dam in Guney et al (2014). sudden collapse, which was simulated by a trapezoidal breach on the dam body.…”

“…10 shows the locations of the level sensors on the map. The details on the physical model and experiments can be found in Guney et al (2013Guney et al ( , 2014.…”

“…These studies mainly focused on definition of flow characteristics at the time of failure, the failure mechanism and flood wave propagation, using idealized and oversimplified physical models. Most recently, Guney et al (2014) carried out dam-break flow experiments in a distorted physical model of Ü rkmez Dam, which consisted of dam reservoir, dam body and downstream area including Ü rkmez Town. The constructed physical model included topographic details in the floodplain such as elevated roads, streambeds and buildings as well.…”

“…The two-dimensional hydrodynamic model results of the hypothetical dambreak scenario were analyzed in GIS, and the peak inundation depth, peak velocity and time moment of the peak inundation depth maps were prepared for the floodplain downstream of Ü rkmez Dam. The two-dimensional numerical model results were also tested against the experimental data from the distorted physical model (Guney et al 2014), which replicates the body and reservoir of Ü rkmez Dam, and the downstream area including Ü rkmez Town. flood hydrograph for the hypothetical dam-break scenario.…”

Numerical Simulation of Flood Wave Propagation in Two-Dimensions in Densely Populated Urban Areas due to Dam Break

“…Vajont Dam, a concrete arch dam with 267 m height in Venice, Italy, collapsed in 1963. It was the most disastrous event in dam failure history with a death toll of more than 2,000 people (Guney et al 2014). The rock-fill Tous Dam in Spain, as a result of heavy rainfall, broke down in 1982, resulting in flooding of 300 km 2 of inhabited land, towns, and villages.…”