Flash-floods that occur in the southern Mediterranean region of France result in significant casualties and economic impacts. Remote techniques such as image analysis offer an opportunity to improve the accuracy of flow rate measurements during such events, by measuring the surface flow velocities. During recent floods of the Ardèche river, discharge measurements by Large-Scale Particle Image Velocimetry (LSPIV) were conducted at the Sauze-Saint-Martin gauging station. Mobile LSPIV measurements were carried out using a telescopic mast with a remotely controlled platform equipped with a video camera. Also, LSPIV measurements were performed using the images recorded by a fixed camera. The rating curve is well documented, with gauged discharge ranging from 4.8 m³/s to 2700 m³/s, i.e. mean velocity from 0.02 m/s to 2.9 m/s. A float coefficient value of 0.90 (±0.10) was derived from the analysis of velocity profiles established from available gauging datasets. For a discharge roughly equal to 300 m³/s, LSPIV velocities throughout the river cross-section were found to be in good agreement (10%) with concurrent measurements by Doppler profiler (ADCP). For discharges ranging from 300 to 2500 m³/s, LSPIV discharges usually were in acceptable agreement (