Abstract: The surveying and mapping equipment of underwater topography change caused by scour lags behind in hydraulic model experiment. Instantaneous terrain data of local scour around bridge pier cannot be acquired in real time at present; and the model verification experiment on scour mechanism and dynamic development process cannot be carried out with convenience. In view of this, we developed an automatic contour drawing device for instantaneous topographic data of local scour of model pier.Through laboratory model experiment, we optimized the performance index of each component and quantified the design parameters of drawing equipment. We also analyzed the precision in model application and the applicability in prototype project. Model experiments manifested that the equipment is of simple structure, convenient operation and low processing cost. It can quickly obtain the instantaneous topographic contour of local erosion in the dynamic process with high precision and sensitivity. It is suitable for rapid underwater topographic mapping in the study of flow field characteristics influenced by local scour development, and is also applicable to the monitoring of underwater terrain around water-involving buildings when molded with enlarged scale.

Key words: bridge piers, local scour, underwater topography, surveying and mapping equipment, river engineering model experiment