Spanish regulation on dam safety recommends the estimation of a return period of 1000 years for the Design Flood and of 10,000 for the Safety Check Flood. The criteria used for the calculations are based on Flood frequency analysis (FFA) from gauge record data or on the Probable Maximum Flood (PMF) which is the hypothetical maximums of rainfall turned into runoff. The short gauge records affords little support for the FFA and for the hypothetical PMF, which in addition the absence of a probability associated, limits the utility of these indices for risk-based dam safety decisions. Palaeoflood techniques are a means to directly assess the probability of extreme floods and test the validity of the PMF-based models. In this paper, palaeoflood record was applied to a case study in the Guadalentín river, upstream of the Valdeinfierno reservoir (372 km2). The Valdeinfierno dam spillway has a capacity of 550 m3s-1. (design flood). In addition, available historical flood data was collected. Palaeoflood data, together with the gauge record, was combined for the FFA, using existing methods for the fitting of distribution functions, such as the maximum likelihood. These return periods are compared with the PMF results. Palaeoflood analysis provides a discharge of 2350 m3s-1 for the design flood (1000-yr return period), and 3450 m3s-1 for the safety check flood (10,000 yr-return period). Some recommendations for the calculation of the safety check flood and design flood are provided which can improve existing legislation on dam safety.

Este trabajo se ha realizado con la financiación del Proyecto CICYT REN2001-1633/RIES “Incorporación de datos de paleocrecidas e inundaciones históricas al cálculo de la avenida de diseño de presas” (PALEOCAP).

Peer Reviewed