Palaeoflood records applied to assess dam safety in SE Spain

Abstract

Spanish dam safety regulations recommend the estimation of a return period of 1000 years for the Design Flood and of 10,000 for the Safety Check Flood, which are obtained from Flood Frequency Analysis (FFA) or on the Probable Maximum Flood (PMF). Short gauge records afford little support for the FFA or the hypothetical PMF, which in addition to the absence of an associated probability, limits the utility of these indices for risk-based dam safety decisions. Palaeoflood hydrology was applied to the Guadalentin River, upstream of the Valdeinfierno reservoir (372 km(2)), which has a spillway capacity of 550 m(3)s(-1) (design flood). Palaeoflood data and gauge station records, were combined for the FFA, using the maximum likelihood estimates of the parameters for a Gumbel distribution, providing a discharge of 2350 m(3) s(-1) for the design flood (1000-yr flood) and 3450 m(3) s(-1) for the safety check flood (10,000-yr flood). The PMF discharge is 5786 m(3)s(-1), showing an overestimation of this empirical method.