Dam Break Analysis of Gembong Dam Using Zhong Xing HY21

Dams are a form of effort to conserve or protect water resources. The function of the Dam as a reservoir for water, irrigation, power generation, and flood control. However, in addition to its huge benefits, dam construction also can endanger the community’s safety, namely in the form of dam breaks. The main causes of dam break are overtopping and piping. So that analysis is needed related to dam break to minimize the impact. Based on the Zhong Xing HY21 software, the most severe impact of the break of the Gembong Dam was due to overtopping using the QInflow PMF design flood of 724.142 m3/s. It resulted in an inundation area of 54.682 km2 with a maximum inundation height of 5.129 m. As a result of the break of the Gembong Dam, 37 villages downstream of the Gembong Dam were flooded. There are 80.819 people affected by this risk. It is stated that all affected villages are at the 4th hazard classification level or very high hazard.

Dam break analysis using 1D geometry at Jatigede Dam, Sumedang

Dam breaks can result in flash floods which have enormous destructive power. This destructive force becomes even more significant when the dam break occurs in a dam with a large capacity. An example is the Jatigede Dam, which has a capacity of 1,060 million m3. To determine the flash flood characteristics and potential impact of the collapse of the Jatigede Dam, an analysis of the dam break was carried out using HEC-RAS software. The dam break scenario uses a Probable Maximum Flood (PMF) inflow with the partial opening of two spillway gates in the middle, which causes the dam overtopping. The Froehlich and Von Thun, and Gillette regression methods were used to defining the breach parameters. Based on the dam break analysis, the simulated flash flood of the Von Thun-Gillette method resulted in a higher velocity and lower water surface elevation than the Froehlich method. The difference in the velocity, dimension of the breach shape, water surface elevation, and discharge is caused by the breaching shape and breach formation time.

A New Dam-Break Outflow-Rate Concept and Its Installation to a Hydro-Morphodynamics Simulation Model Based on FDM (An Example on Amagase Dam of Japan)

Dams are constructed to benefit humans; however, dam-break disasters are unpredictable and inevitable leading to economic and human life losses. The sequential catastrophe of a dam break directly depends on its outflow hydrograph and the extent of population centers that are located downstream of an affected dam. The population density of the cities located in the vicinity of dams has increased in recent times and since a dam break hydrograph relies on many uncertainties and complexities in devising a dam-break outflow hydrograph, more researches for the accurate estimation of a dam-break flood propagation, extent and topography change becomes valuable; therefore, in this paper, the authors propose a novel and simplified dam-break outflow rate equation that is applicable for sudden-partial dam breaks. The proposed equation is extensively affected by a dam-break shape. Therefore, the inference of a dam-break shape on a dam-break outflow rate is investigated in the current study by executing hydraulic experiments in a long, dry bed, frictionless and rectangular water channel connected to a finite water tank to acquire a mean break-shape factor. The proposed equation is further validated by regenerating the Malpasset dam-break hydrograph and comparing it to the existing methods and also by installing it on an existing 2D hydro-morphodynamics flood simulation model. Finally, Amagase Dam’s (arch-reaction dam in Japan) break simulation is executed as a case study. The results of the simulations revealed that the greater the height of a dam-break section, the more devastating its flood consequences would be.

When the Dam Breaks

This article provides an overview of the key events in Catalonia during 2019. In order to put the events in context, the article begins with a brief overview of the recent history of Catalonia and its relationship with the rest of Spain. Particular attention is placed on the events of 2014 through 2017 and, in particular, the second unauthorized referendum and its aftermath. The article then focuses on the protests, counter- protests and clashes with the police that followed the sentencing of Catalonian officials in October 2019. The article concludes with an examination of the lack of role the European Union has had on this conflict and minority issues generally and what this all means for Spain and Catalonia moving forward.

Large scale filed experiment on the landslide dam breaching

<p>Landslide dam breaching is the one of focus topics in the geophysical flows. The frequency of occurrence of landslide dam increases due to earthquake, climate change and mans activities in recent years. Once the dam breaks, it would trigger extreme flood downstream. A field experiment on landslide dam breach has been carried out on a small mountain river in Mianzhu, Sichuan Province, China from 23 November to 29 December, which aims to reveal impact of different diversion channel types on the dam breaching process as well as the resulting flood. The dam is of 4m high, 10~15m wide. the length of the dam crest is 5m, upstream downstream slopes of the dam are 1:2 and 1:5. Results show division channel can reduce the peak flood discharge obviously. The pilot vertical fall can trigger earlier back erosion and thus peak discharge appears earlier with smaller magnitude.</p>

DAM BREAK WAVE, TIDAL BORE, IN-RIVER TSUNAMI SURGE: WHAT THE HELL?

Flood waves resulting from dam breaks have been responsible for numerous losses of life through centuries. Both the 26 December 2004 tsunami and 11 March 2011 Tohoku catastrophes were human tragedies of international significance. An important point is the physical analogy between dam break waves travelling downstream, tidal bores progressing deep inland, in-river tsunami propagating upstream, as well rejection surges in hydropower canals. The leading edge is a hydrodynamic shock, with a marked discontinuity in free-surface elevation and velocity and pressure fields, and a tri-phase flow with three distinct flowing phases, i.e. liquid (water), solid (sediment) and gas (air). Seminal features of bores and surges include a net mass flux, the breaking in shallow waters, and the intense turbulence at the front associated with massive sedimentary processes and air entrainment in the breaking roller. In this keynote talk, physical experiments, numerical CFD modelling and field observations are presented and compared. Current knowledge gaps are discussed. Ultimately it is argued that the 'solitary wave' analogy is not directly relevant to model the unsteady turbulent mixing of in-river tsunami surges, tidal bores and dam break waves.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/SQaPoSj2lP4