Using High-Resolution Satellite Rainfall Products to Simulate a Major Flash Flood Event in Northern Italy
Using High-Resolution Satellite Rainfall Products to Simulate a Major Flash Flood Event in Northern Italy
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DOI：
10.1175/jhm-d-12-09.1
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发表时间：
2013-02
影响因子：
3.8
通讯作者：
E. Nikolopoulos;E. Anagnostou;M. Borga
中科院分区：
文献类型：
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作者：
E. Nikolopoulos;E. Anagnostou;M. Borga
连续的山洪警报程序通常受到山洪发生的山区流域降水观测限制的阻碍。在复杂的地形区域可以利用卫星进行降雨量估计，这为观测覆盖问题提供了一种可能可行的解决办法。然而，卫星估算的重降雨率与水文模型中非线性传播的显著偏差和随机误差相关，严重限制了这些产品在洪水预报中的使用。在这项研究中，使用三个准全球和近实时的高分辨率卫星降雨产品模拟山洪暴发在复杂的地形流域进行了调查。该研究使用了一个主要的闪光事件，发生在2003年8月29日的中等大小的山区盆地（623平方公里）在东意大利阿尔卑斯山。将卫星降雨量与通过测量仪校准的气象雷达估计得出的降雨量进行比较表明，尽管卫星产品存在很大的偏差，但它们可以代表流域平均降雨量的时间变化。卫星降雨通过分布式水文模型的传播表明，降雨的系统误差被严重放大时，转换为错误的径流干燥的初始土壤条件下。模拟过程线变得有意义后，重新校准模型为每个卫星降雨输入分别。然而，重新校准后模型参数的不切实际的值表明，这种方法是错误的，使用卫星降雨量数据重新校准模型应谨慎对待。总体而言，这项研究突出了需要改进的卫星降雨量反演算法，以允许更适当地使用卫星降雨量产品的山洪应用。
Effectiveflash flood warning procedures are usually hampered by observational limitationsof precipitation over mountainous basins where flash floods occur. Satellite rainfall estimates are available over complex terrain regions, offering a potentially viable solution to the observational coverage problem. However, satelliteestimatesofheavyrainfallratesareassociatedwithsignificantbiasesandrandomerrorsthatnonlinearly propagate in hydrologic modeling, imposing severe limitations on the use of these products in flood forecasting. In this study, the use of three quasi-global and near-real-time high-resolution satellite rainfall products for simulating flash floods over complex terrain basins are investigated. The study uses a major flash floodeventthatoccurredduring29August2003onamediumsizemountainousbasin(623 km 2 )intheeastern Italian Alps. Comparison of satellite rainfall with rainfall derived from gauge-calibrated weather radar estimates showed that although satellite products suffer from large biases they could represent the temporal variability of basin-averaged precipitation. Propagation of satellite rainfall through a distributed hydrologic model revealed that systematic error in rainfall was severely magnified when transformed to error in runoff under dry initial soil conditions. Simulation hydrographs became meaningful only after recalibrating the model for each satellite rainfall input separately. However, the unrealistic values of model parameters after recalibration show that this approach is erroneous and that model recalibration using satellite rainfall data should be treated with care. Overall, this study highlights the need for improvement of satellite rainfall retrieval algorithms in order to allow a more appropriate use of satellite rainfall products for flash flood applications.