Abstract: In the paper the accuracy for single beam echosounder interpolations using error propagation law is analyzed. A mathematical model of medium error expression for interpolation of water depth in single beam is established and the results in three experimental zones of a coastal zone in south China is tested. The inverse distance weighting method, shepard method and linear interpolation triangulation method with adaptive Search Radius Method are used to compute the gross error of water depth interpolations in this test. The results show that the ratio of gross errors is less than 5% and the three methods are superior in efficiency and quality. Also, we get that the interpolations' accuracy is related to the precision of data source, but not to the density of data source. In the case of a given depth measurement limit error, we suggest that the limit value of Grid point water depth value should set to be 0.4m in the digital water depth model standards.

Key words: single beam echosounder, digital depth model, interpolation, accuracy