<p>U okviru ovog rada je razvijen ravanski model koji sadrži sve važne aspekte interakcije vode, nanosa i zagađivača u prirodnim vodotocima. Model obuhvata procese<br />strujanja vode, oba oblika kretanja nanosa (suspendovani i vučeni), mehanizme<br />razmene mase između nanosa u suspenziji i nanosa u aktivnom sloju, deformacije korita usled erozije i deponovanja nanosnog materijala, mehanizme razmene<br />mase između nanosa u aktivnom sloju i aktivnom stratumu, kao i procese transporta nekonzervativne zagađuju&acute;ce materije koja je u interakciji sa nanosom preko<br />procesa adsorpcije/desorpcije. Formulisane jednačine transporta zagađivača obuhvataju njegovu pojavu u rastvorenom i adsorbovanom obliku. Razmena između<br />dva vida pojave zagađivača (rastvoreni i adsorbovani) je opisana preko kinetickih<br />procesa prvog reda, pri cemu je modelisanje koeficijenata razmene usko povezano<br />sa dostupnom povrˇsinom za adsorpciju. Sa druge strane, razmena između materije<br />adsorbovane na suspendovani nanos, odnosno materije adsorbovane na nanos u aktivnom sloju je neposredno vezana za nanosne procese uvlačenja zrna u suspenziju i<br />deponovanja istih iz suspenzije. Početni &scaron;ematski testovi su podrazumevali proveru<br />razvijenog algoritma za re&scaron;avanje advektivnih članova jednačina. Druga grupa &scaron;ematskih testova je podrazumevala implementaciju razvijenog modela transporta<br />zagađujuće materije, pri čemu su testirani i kvalitativno ocenjeni mehanizmi<br />razmene i interakcije. Za testiranje modela na primerima aluvijalnih vodotokova<br />izabrane su dve deonice reke Dunav. Prva lokacija se nalazi u pograniˇcnoj zoni<br />između Mađarske i Srbije gde su testirani aspekti modela koji se odnose na<br />proracun tečenja i pona&scaron;anje nanosa. Druga deoncia se nalazi kod Beograda<br />gde je, pored proračuna strujanja i nanosa, vr&scaron;ena analiza modela transporta zagađujuće materije obuhvatajući sve relevantne mehanizme i aspekte izučavanih<br />procesa. Upoređivanjem terenskih merenja i rezultata proračuna je konstatovano<br />da razvijeni model može simulirati interakciju vode, nanosa i zagađivača u prirodnim vodotocima sa zadovoljavajucom tačno&scaron;ću i pouzdano&scaron;ću.<br />&nbsp;</p> / <p>This work presents the development of a two-dimensional model for flow, sediment<br />and pollutant interaction in natural watercourses. The model incorporates water<br />flow computation, both aspects of sediment transport (suspended and bed-load),<br />the mechanisms of exchange between suspended and bed sediment, bed evolution<br />due to erosion and deposition, the mechanisms of exchange between active layer<br />and active stratum sediment, as well as the processes of nonconservative pollutant<br />transport including its interaction with sediment particles by adsorption/desorption.<br />Deriving the governing equations for pollutant transport included the dissolved and<br />adsorbed pollutant. The exchange between the dissolved and adsorbed pollutant<br />was described using a first order kinetic process, while the modeling of the exchange<br />coefficients remained closely related to the sediment surface available for adsorption.<br />On the other hand, the exchange between the pollutant adsorbed on suspended sediment and the pollutant adsorbed on active layer sediment was directly related<br />to the sediment processes of entrainment and deposition. Numerical tests included<br />the evaluation of the developed algorithm for advection terms. The second group<br />of numerical tests targeted the pollutant transport model, with the emphasis on<br />the mechanisms of exchange and interaction. For field test cases two reaches of the<br />Danube River were used. The first reach was located in the border area between<br />Hungary and Serbia. Field data collected there was used to analyze the developed<br />model&rsquo;s ability to simulate flow and sediment transport. Data collected on the second reach near Belgrade was used to perform flow, sediment and pollutant transport<br />simulations, taking into account all the relevant mechanisms of the studied processes.<br />Comparing the computed and measured values, it was concluded that the developed<br />model is able to simulate the interaction of flow, sediment and pollutant in natural<br />watercourses with acceptable precision and reliability.</p>