Stilling basins dissipate energy in order to form hydraulic jumps and rotational flows. Hydraulic jump and rotational current phenomenon produces pressure fluctuation at the bottom of stilling basins. In the present study, pressure fluctuations and their locations have been studied in a physical model of Namrod Dam. Results showed that fluctuations in presence of jump in the basin are high and therefore the fluctuation factors are respectively high. In Positive pressure coefficient (CP+), it is evident that when a jump is present, the turbulence and disturbance factors increase and therefore the pressure fluctuations go up respectively. In Negative pressure coefficients (CP-), as is expected from positive pressure coefficients, the maximum pressure fluctuations occurred in Q/Qmax= 0.47 regarding to form a complete hydraulic jump at this discharge. Regarding available empirical equations, the thickness of slab for different hydraulic conditions were calculated and compared in one dimension (1D) and two dimension (2D) conditions. By analyzing collected data, it was observed that, results of 1D were underestimated in comparison by 2D calculations. Concrete slab thickness could be observed that fluctuations have significant effect on thicknesses. However, such calculations can provide designers with general ideas how to better understand the conditions.

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