Characteristics of maximum discharges on torrential watersheds in Serbia

Abstract

Torrential floods are the most frequent phenomenon in the arsenal of 'natural risks' in Serbia (droughts, avalanches, landslides, rockslides, hail, forest fires, storm wind and earthquakes). Regime of occurrence of floods was studied on the basis of investigations carried out on 128 control profiles, on all important river systems in Serbia, south from Sava and Danube. Frequency of event of maximum discharge Q(max), over determined threshold, defined as average maximum discharge Q(max av),was analysed. The primary maximum of frequencies was noticed in the period May-June, and the secondary maximum of frequencies in the period February-March. The absolute maximum discharges Q(max ab) on certain profiles follow the periods with the most expressed frequencies, but there are also significant exceptions. A few equations have been derived, which point out close relations between average maximum discharge Q(max av), magnitude of the catchment area A, average annual discharge Q(av) and the absolute maximum discharge Q(max ab) [Q(max av) = f(A); Q(max av) = f(Q(av)); Q(max av) = f(A, Q(av)); Q(max ab) =f(Q(max av))]. Historical cases of maximum discharges, reconstructed on the basis of 'hydraulics flood traces', are presented.