Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 4 1 2000 10.5194/hess-4-155-2000 http://www.hydrol-earth-syst-sci.net/4/155/2000/ http://www.hydrol-earth-syst-sci.net/4/155/2000/hess-4-155-2000.html http://www.hydrol-earth-syst-sci.net/4/155/2000/hess-4-155-2000.pdf 155 172 0000-00-00 Comparative analysis of some methods for deriving the expected flood reduction curve in the frequency domain M. Franchini G. Galeati Department of Engineering, University of Ferrera, Via Saragat 1, 44100 Ferrara, Italy ENEL S.p.a., Production Division, Hydraulic Engineering, Hydrology Unit, C.so del Popolo 245, 30172 Mestre-Venezia, Italy e-mail for corresponding author: mfranchini@ing.unife.it This article compares the results of three different models, namely empirical, geomorphoclimatic and stochastic, proposed in the literature for synthesising the reduction curve of average river discharges, of given frequency, over different durations. The analysis used observed reduction ratios inferred for twelve recording gauge stations with known rating curves, situated on central Italian watercourses all of which flow into the Adriatic sea. Particular emphasis was laid on the difficulties encountered in the parameterisation of the models, on the relations between the different formulations and on the existence of a link between the model parameters and the characteristic response times of the basins.