洪水淹没分析中的自适应逐点水位修正算法

Adaptive Water Level Correction Algorithm for Flooding Analysis

洪涝灾害损失评估是防洪减灾科学决策的基础,其中洪水淹没分析是准确提取洪水淹没范围、水深及历时等灾情信息的关键。洪水淹没分析主要采用数字高程模型数据,由于DEM的格网分辨率与高程精度有限,常出现异常的洼地或平地,导致难以可靠地计算每个格网点处的流向,而传统方法采用统一高程的洼地填平处理又使得容易出现洪水演进过程中复杂起伏地形水面爬坡以及平坦地形水位断流的问题,为此提出顾及流速和淹没时间的自适应逐点水位修正算法,即在DEM坡面流模拟的基础上,根据洪水水流特性、地形、边界变化、水流速度、水深变化以及淹没点的淹没时间,计算水位修正值,对洪水演进过程中每个格网点的水位进行修正,采用多种地貌类型的DEM数据进行试验,证明洪水演进的淹没范围、水深及历时的实时计算结果准确可靠,可为快速评估灾害损失与防洪决策服务提供更为科学的依据。

Flood 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. The limited resolution and random error of DEM result in abnormal depressions which impede the computation of flow direction. the same elevation to create a Traditional methods process the depressions in DEM by filling the depressions with 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, an adaptive water level correction algorithm for accurate flooding analysis is presented to derive more correct 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 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.