In this work, a preliminary assessment has been made of the impact that the bridge along Wrocławska and Częstochowska streets has on the conditions of flood flow. Calculations were made for a flow with a probability of exceedance p = 1% amounting to 100 m3 · s–1. Based on the field tests performed in the designated section of the Kłodnica river from km 49 + 799 to km 49 + 739, i.e. geodetic measurements of the Kłodnica riverbed and technical inventory of the analysed bridge object, a digital terrain model (NMT) was developed, followed by hydraulic calculations of the water flow Q1% and the flow accumulation (damming) in the clear span of the Wrocławski bridge. The accumulation height was calculated using the formula given in the study by Bajkowski et al. [2000]. Calculations of the accumulation height of designed flow in the clear span of the bridge were also made using the HEC-RAS program. The calculations were made in two variants – in the first variant, calculations were performed for the selected section of Kłodnica without a bridge, and in the second variant, with the bridge. The so-called clear span reserve (bridge clearance) was also calculated, computed as the difference in ordinates of the keystone arch of the bridge span and the stacked water table of the design flow in the bridge clear span. The obtained calculation results indicate no risk of Q1% flow accumulation in the cross- section of the Wrocławski bridge. The calculated accumulation of the design flow will not cause flooding from the Kłodnica riverbed. Preliminary conclusions indicate a possible necessity to verify flood hazard zones for the flow with a probability of exceedance p = 1%, developed for the Kłodnica river in the centre of Gliwice town, developed as part of the ISOK project.