Definition of seasonal freeboards using risk analysis models
Author(s): Vicent J.Espert-Canet, Manuel Gómez de Membrillera-Ortu?o, Ofiteco Spain
Pages: 63-67
Year: 2016 Issue: 6
Journal: Large Dam and Safety
Keyword: risk analysis model; flood; seasonal freeboard;
Abstract: This paper describes a simple method for the definition and verification of seasonal free-boards taking advantage of elements that make up a risk model, focusing on hydrological safety, and pro-vided that hydrological data and reasonably long incoming flow series are available.Definition of seasonal freeboards can be a complex problem involving many variables, such as safety,hydrological analysis, dam user requirements, applicable safety regulations and economic analysis, withsafety priorities often being at odds with an efficient operation. Thus, a dam-reservoir risk model, which en-compasses most safety related aspects, becomes an efficient way to integrate this wide range of variables.The first step in the evaluation of the seasonal freeboards is a characterization of the seasonal hy-drology. Often, lack of sufficient data, such as historic pool levels or incoming water flow adds uncertain-ty to this analysis, so simplified methods have to be adopted. A flood routing model must then be used,establishing a relationship between incoming seasonal floods, freeboards and peak outflow. The possibili-ty of overtopping must also be addressed.A downstream consequences model, which links dam outflows and possible damages, including lossof human life may then be applied.The final goal is to obtain, for any given flood, its seasonal probability(and its return period), thedam-reservoir response(as an outflow, or even overtopping), and then its downstream consequences, sothat a sensibility analysis can be made. Minimal seasonal freeboards for any safety condition can then bedirectly found.A case study will be provided, in which seasonal freeboards are analyzed and verified for a largeSpanish dam, taking into account data availability, operating rules, downstream flood consequences andlegal requirements.
Pages: 63-67
Year: 2016 Issue: 6
Journal: Large Dam and Safety
Keyword: risk analysis model; flood; seasonal freeboard;
Abstract: This paper describes a simple method for the definition and verification of seasonal free-boards taking advantage of elements that make up a risk model, focusing on hydrological safety, and pro-vided that hydrological data and reasonably long incoming flow series are available.Definition of seasonal freeboards can be a complex problem involving many variables, such as safety,hydrological analysis, dam user requirements, applicable safety regulations and economic analysis, withsafety priorities often being at odds with an efficient operation. Thus, a dam-reservoir risk model, which en-compasses most safety related aspects, becomes an efficient way to integrate this wide range of variables.The first step in the evaluation of the seasonal freeboards is a characterization of the seasonal hy-drology. Often, lack of sufficient data, such as historic pool levels or incoming water flow adds uncertain-ty to this analysis, so simplified methods have to be adopted. A flood routing model must then be used,establishing a relationship between incoming seasonal floods, freeboards and peak outflow. The possibili-ty of overtopping must also be addressed.A downstream consequences model, which links dam outflows and possible damages, including lossof human life may then be applied.The final goal is to obtain, for any given flood, its seasonal probability(and its return period), thedam-reservoir response(as an outflow, or even overtopping), and then its downstream consequences, sothat a sensibility analysis can be made. Minimal seasonal freeboards for any safety condition can then bedirectly found.A case study will be provided, in which seasonal freeboards are analyzed and verified for a largeSpanish dam, taking into account data availability, operating rules, downstream flood consequences andlegal requirements.
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