The hysteresis phenomenon in unsteady flows causes a discrepancy between the actual discharge and the discharge estimated from single valued rating curves, thereby reducing the accuracy of flow monitoring and measurement. This study investigates the effect of hydrograph characteristics on hysteresis intensity, focusing on symmetric triangular hydrographs. To generalize the results, the effective physical parameters—including base discharge, hydrograph height, and base time—were transformed into three dimensionless parameters: the base flow Froude number, the hydrograph height Froude number, and the dimensionless time. The study is based on 192 physical experiments conducted in a hydraulically long flume 60 m in length with a trapezoidal cross section (30 cm bed width, 1:1 side slopes, and 25 cm depth). The results show that hysteresis intensity is directly influenced by hydrograph characteristics. With other parameters held constant, increasing the dimensionless time initially increases hysteresis intensity, reaches a maximum at mid range values, and subsequently decreases it. Furthermore, increasing the hydrograph height Froude number intensifies hysteresis across the entire range of dimensionless time, whereas increasing the base flow Froude number diminishes it.