Seite - 1256 - in Book of Full Papers - Symposium Hydro Engineering

Usually, it is not advisable to provide higher dam safety during construction than current dam safety. The material losses contain losses at the dam itself, benefit losses (water supply, power generation, recreation, fish and wildlife), direct losses to the third parties and indirect economic consequences like water shortage, labor reduction, loss of tourism, etc. [5]. The dam break flood extent modelling and hazard mapping is performed by contemporary hydraulic models combined with GIS tools (fig. 1). The census data serve for the assessment of direct losses. Fig. 1 Area affected by dam break flood cause by breaching of the Cholticky dam [11] As the principal task is to specify necessary reservoir water level drawdown, losses caused to environment, fish population, recreation and others due to drawdown should be taken into account for selected variants of water levels. The cost benefit analysis should be applied as an appropriate tool for the balancing of material consequences. The annual probability pK of the flood for the dam protection during its reconstruction can be determined using the material losses due to dam failure LK and financial losses LL due to reservoir level drawdown during the remedial works: 𝑝 𝐾 ≤ 𝑝 𝐿 ⋅𝐿 𝐿 𝐿 𝐾 [2] Probability pL depends on the duration of necessary drawdown, e.g. in case of one year drawdown pL = 1. For the potential loss of life estimate numerous guidelines [1; 2; 7] have been published. The experience from the real dam incidents and failures [10] shows extremely strong dependence on warning time, when about 50% of the population at risk can be evacuated in the first hour, 75% within two hours, and that complete evacuation requires more than 10 hours. Expected warning time depends on the level of warning and rescue systems and may significantly differ from country to 1256