The paper presents results of calibration and verification of one-dimension numerical model of the Wislok River from Besko reservoir to the estuary to the San River. In order to evaluate the quality of this model following coefficient were used: the correlation coefficient, special correlation coefficient, total square error and errors of culmination level, culmination flow, culmination dislocation and flood wave volume. Observations of water levels in the Wislok River are conducted on 5 river gauges. An 5 another gauges are located on the tributaries of the Wisłok River. The ve-rification and calibration process carried out on the waves in 1987 and 1998 al-lowed to confirm the correctness of the hydraulic model in the sector from the river gauge Besko to the Rzeszow river gauge. Between Rzeszow and Tryncza river gauges volumes of waves are not balanced which enforces the admittance in the hydrological model of negative values of a lateral inflow. The volume of 1987 flood wave in the node of the three river gauges in Wislok-San system indicates that the wave is balanced on the Tryncza stream gauge.The performed simulations of the flood wave transformation on the whole Wislok River for different computable scenarios, with usage of hydro-informatic software - ...