Abstract
An inexpensive GPS fish finder which is built with side scan sonar function is applied to measure nearshore zone topography. To estimate a survey error by the GPS fish finder, a survey using Total Station had been con-ducted to achieve qualified accurate topography data set. The survey data using Total Station and GPS fish finder are compared. Then, it is found that an survey data accuracy using GPS fish finder is as much as 1.2 to 1.6 times of the error that is accepted by the legal criteria (survey law and hydrographic law), therefore this survey techniques using GPS fish finder cannot apply to a legal survey, but can apply to an environmental study that require reasonably accurate topography. In addition, to develop an aquatic GIS including topography, water quality and bottom condition data, an effective measurement procedure of water quality is also described.
