The hydraulic parameters of the flow of water and sediment with the assumption of the steady flow and the changes of the geometry of cross-sections are defined standard mathematical methods for the help of one dimensional models. The one dimensional model MORMO (MORphologisches MOdell) is example of such model, worked out by Schilling and Hunziker [1995] in the Hydraulic Engineering Laboratory of Swiss Federal Institute of Technology in Zurich. The numeric calculations of silting the Rzeszów water reservoir, on the basis of the thirteen-year-old sequence of hydrological, including the average hour flows of water and the answering them concentrations of suspended sediments, executed for the help of the program MORMO, they were compared with the results of the measurements of silting. Affirm that the obtain for the help of the one dimensional model MORMO the longitudinal profile of the water reservoir in Rzeszów, representing the change of the bottom in the result of silting, its answer the real course of the bottom changes. The proceeding of the real course of silting was not obtain because the time of silting, definite according to the simulation turned out shorter until real silting time, carrying out 13 years.

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