关键词: 风险分析模型, 洪水, 季节性安全超高

Abstract: This paper describes a simple method for the definition and verification of seasonal freeboards taking advantage of elements that make up a risk model, focusing on hydrological safety, and provided 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, with safety priorities often being at odds with an efficient operation. Thus, a dam-reservoir risk model, which encompasses 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 hydrology. Often, lack of sufficient data, such as historic pool levels or incoming water flow adds uncertainty 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 possibility of overtopping must also be addressed.
A downstream consequences model, which links dam outflows and possible damages, including loss of human life may then be applied.
The final goal is to obtain, for any given flood, its seasonal probability (and its return period), the dam-reservoir response (as an outflow, or even overtopping), and then its downstream consequences, so that a sensibility analysis can be made. Minimal seasonal freeboards for any safety condition can then be directly found.
A case study will be provided, in which seasonal freeboards are analyzed and verified for a large Spanish dam, taking into account data availability, operating rules, downstream flood consequences and legal requirements.

Key words: risk analysis model, flood, seasonal freeboard