Kanso A, Chebbo G, Tassin B
Centre d'Enseignement et de Recherche Eau, Ville et Environnement, Ecole Nationale des Ponts et Chaussées, 6-8 avenue Blaise Pascal, 77455 Marne-la-Vallée, France.
Water Sci Technol. 2005;52(5):135-42.
Previous research has confirmed that the sediments at the bed of combined sewer systems are the main source of particulate and organic pollution during rain events contributing to combined sewer overflows. However, existing urban stormwater models utilize inappropriate sediment transport formulas initially developed from alluvial hydrodynamics. Recently, a model has been formulated and profoundly assessed based on laboratory experiments to simulate the erosion of sediments in sewer pipes taking into account the increase in strength with depth in the weak layer of deposits. In order to objectively evaluate this model, this paper presents a Bayesian analysis of the model using field data collected in sewer pipes in Paris under known hydraulic conditions. The test has been performed using a MCMC sampling method for calibration and uncertainty assessment. Results demonstrate the capacity of the model to reproduce erosion as a direct response to the increase in bed shear stress. This is due to the model description of the erosional strength in the deposits and to the shape of the measured bed shear stress. However, large uncertainties in some of the model parameters suggest that the model could be over-parameterised and necessitates a large amount of informative data for its calibration.
先前的研究已经证实，合流制排水系统底部的沉积物是降雨事件期间颗粒和有机污染的主要来源，这会导致合流制排水系统溢流。然而，现有的城市雨水模型使用了最初从冲积水动力学发展而来的不恰当的泥沙输运公式。最近，基于实验室实验制定并深入评估了一个模型，以模拟污水管道中沉积物的侵蚀情况，同时考虑到沉积物弱层中强度随深度的增加。为了客观评估该模型，本文使用在巴黎污水管道中已知水力条件下收集的现场数据对该模型进行贝叶斯分析。测试使用马尔可夫链蒙特卡罗（MCMC）采样方法进行校准和不确定性评估。结果表明，该模型能够将侵蚀作为对床面剪应力增加的直接响应进行再现。这是由于该模型对沉积物侵蚀强度的描述以及所测床面剪应力的形状。然而，一些模型参数存在较大不确定性，这表明该模型可能参数化过度，并且校准需要大量信息丰富的数据。
