Abstract: The spatial analysis and 3-D analysis modules in GIS software were employed to analyze the monitoring data of dam settlement during impoundment. In addition, 3-D simulation graphs of the dam settlement in different periods plotted by TIN model were compared with other monitoring indexes. It 's revealed that the settlement thematic maps and statistical charts and diagrams are more rapidly and conveniently generated, and contain more information with more accuracy than those by traditional methods. The intuitive and vivid 3-D simulation graphs of the settlement provide technical support for the whole project by informing decision  makers and engineers the latest settlement and deformation situation. In conclusion, it ' s rapid and accurate in reflecting the settlement monitoring results.

Key words: reservoir impoundment ,    settlement monitoring ,    GIS  ,   TIN