A methodology for analysing return periods for design discharges in Spanish dam spillways

摘要

The aim of this article is to develop an integrated methodology for a Geographical Information System to estimate maximum discharge frequency laws in non altered basins. The Modified Rational Method (MRM) has been selected from the hydrometeorological methods available, because it is a simple model for transforming rainfall into runoff, and can be used in average-sized basins (up to 3,000 km~2) in a non altered regime. The proposed methodology consists of developing the MRM in the Geografical Information System (GIS) GRASS of the US Army Corps of Engineers, which makes it possible to jointly process a high number of basins located throughout the country and to calculate the maximum discharge frequency laws. A set of catchment areas have been selected, which flow into large dams, where sufficient and reliable information is available and where the basins involved do not exceed the limits determined by the methodology. The results obtained have served to carry out a preliminary statistical analysis of the maximum discharges used in their design.