关键词: 洪水淹没, DEM, 洼地, 水位自适应修正, 水面爬坡, 水位自阻断流

Abstract: Flood loss assessment is the basis of flood control and disaster mitigation decision-making, and the primary tasks in flood assessment are to pinpoint the flooding area, depth of water and duration of flooding based on Digital Elevation Model (DEM). The limited resolution and random error of DEM result in abnormal depressions which embarrass the computation of flow direction. Traditional methods process the depressions in DEM by filling the depressions with the same elevation to create a depression-free surface, which result in new problems like the up-lifting of water level on slopes and flood cut-off in flat area. To overcome these shortcomings, this paper presents an adaptive water level correction algorithm for accurate flooding analysis to derive flooding area, flood depth and duration time. According to the characteristics of floods, the correction value is adaptive to flood rate, flood depth variation and flooding time. Terrains of different types range from flat to hilly to mountainous are selected for testing. Experimental results prove that by means of this method, more accurate and reliable flooding information can be available, which is prior to scientific and prompt flood assessment and decision-making.

Key words: Flooding analysis, DEM, Depressions, Water Level Correction, Up-lifting of water level, flood cut-off