介绍了水库淹没区的基本概念，分析了传统基于二维的水库淹没区范围和基于 DEM 模型的水库淹没区范围 2 种计算方法的不足，及它们计算水库淹没区范围存在误差的原因。提出了一种基于 3D GIS 的计算水库淹没区范围的算法，并列举了所提算法用来计算水库淹没区范围的基本流程，论证了该算法在理论上的可行性和在实践中的有效性。

In this paper, the basic concept of the reservoir submerged area is introduced. The disadvantages of two algorithms, i.e., the reservoir submerged area based on two-dimension and DEM model, and the reasons inducing errors for calculating the reservoir submerged area using this two algorithms are analyzed. Finally, an algorithm of the reservoir submerged area based on 3D GIS is presented. The basic process of calculating the reservoir submerged area using the proposed algorithm is analyzed. The feasibility in theory and the effectiveness in practice of the presented algorithm are proved.