ODREĐIVANJE RAČUNSKIH PROTOKA MODELOM PADAVINE-OTICAJ NA MALIM SLIVOVIMA

This paper presents development and application of the model aimed at simulating peak flood runoff from the small river basin Obnica in Serbia (having an area of 185 km2) with an aim to estimate design floods using different approaches. The model is developed using the HEC-HMS software (The United States Army Corps of Engineers (USACE) Hydrologic Centre’s Hydrologic Modelling System). The model is calibrated against eight events with observed hydrographs and corresponding rainfall, and verified with a separate set of events. Flood hydrographs are simulated with the constant intensity design storms of various durations and with the 24-hour design storm with design hyetograph determined using the alternating block method. All design floods obtained from the simulated hydrograph peaks are compared with the design floods estimated by statistical analysis of annual maximum flows. The results have shown that the temporally distributed 24-hour storms yield the design floods that are the closest to the statistically derived design flows, while the constant intensity storms cannot reproduce the statistically derived design flows.U ovom radu je predstavljen model za simulaciju pika poplavnog talasa na malom slivu reke Obnice u Srbiji (površine 185 km2) sa ciljem određivanja računskih velikih voda koristeći različite pristupe. Primenjen simulacioni model je napravljen u HEC-HMS programu (The Unated States Army Corps of Engineers (USACE) Hydrologic Center’s Hydrologic Modeling System). Model je kalibrisan na osnovu osam snimljenih hidrograma i odgovarajućih kišnih epizoda i verifikovan za hidrograme i kišnie epizode koji nisu učestvovali u procesu kalibracije. Za simulaciju su korišćene računske kiše konstantnog inteziteta različitog trajanja kao i kiše trajanja 24 časa čiji je hijetogram formiran metodom alternativnih blokova. Svi simulirani protoci upoređeni su sa protocima dobijenim statističkom analizom maksimalnih godišnjih protoka. Rezultati pokazuju da se uključivanjem vremenske neravnomernosti u računske kiše trajanja 24 časa dobijaju vrednosti protoka koje su najbliže rezultatima statističke analize, dok to korišćenjem kiša konstantnog inteziteta nije bilo postignuto