The status of the global positioning system for dam surface monitoring

Dam monitoring relies on the long-term measurement of small structural changes at regular intervals. Traditional surveying techniques and geotechnical instrumentation can effectively monitor one- or two-dimensional modes of motion. However, spatial distribution of geotechnical instrumentation is usually limited to the locations that the instruments can be installed during dam construction, while surface monitoring by traditional surveying techniques is a relatively slow process which restricts the number of points that can be regularly monitored. As a supplement to existing geotechnical instrumentation, the Global Positioning System (GPS) offers a reliable and efficient method for three-dimensional monitoring. To date, GPS technology has been successfully applied to a variety of deformation monitoring applications. This is due to its ease of use, and capability of very high accuracy when the appropriate hardware, software and field procedures are implemented. This paper reviews current GPS technology in the context of its application to dam deformation monitoring and the advantages and disadvantages of using GPS for this type of activity are discussed.