采用数字高程DEM来进行洪水淹没分析和灾害评估是GIS水利应用领域的研究前沿，通过对基于种子蔓延算法的淹没区计算及灾害评估方法的分析，将淹没分为有源淹没和无源淹没两种，进而论述了淹没区计算方法的精度及灾害评估和预测的准确性主要取决于数字地面模型DEM空间数据精度和社会经济信息数据的准确性；而种子蔓延算法及空间叠加运算速度则决定了整个模型的效率，该模型已在国家九五地方重大攻关水利项目中得到成功应用。

Based-GIS studies of flood area and damage evaluation have been being a research focus in GIS application fields. In this paper, a new model of flood area based on seed spread algorithm and of the damage evaluation has been proposed. Two different cases so-called “non-source flood” and “source flood” exist when determining flood area based on DEM and under the given water level condition. Non-source flood corresponds to the case with well-distributed and large-area rainfall where all the low-lying land may have a flood disaster, and in this case all the points with elevations below the given water level should be included in the flood area. The “source flood” is the case of flood (e.g. from bank burst) flushing through the nearby regions and needs to consider “circulating” condition. It is because flood may be obstructed by ring structures or high lands and thus can only covers the place where it can flow and reach. The results of the flood area calculation and damage evaluation can also be visually and dynamically provided in the forms of graph, image, 3D or virtual reality. The model of flood area calculation and damage evaluation proposed in this paper, adopting Microsoft VC++ 6.0 programming language and Microsoft SQL Server 7.0 DBMS platform, has been successfully applied in the “Zhejiang Provincial Water Conservancy Management System” developed for a national project