Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, Skempton Building, London SW7 2AZ, UK.
Water Res. 2012 Oct 1;46(15):4571-86. doi: 10.1016/j.watres.2012.06.037. Epub 2012 Jul 3.
Due to increasing customer and political pressures, and more stringent environmental regulations, sediment and other blockage issues are now a high priority when assessing sewer system operational performance. Blockages caused by sediment deposits reduce sewer system reliability and demand remedial action at considerable operational cost. Consequently, procedures are required for identifying which parts of the sewer system are in most need of proactive removal of sediments. This paper presents an exceptionally long (7.5 years) and spatially detailed (9658 grid squares--0.03 km² each--covering a population of nearly 7.5 million) data set obtained from a customer complaints database in Bogotá (Colombia). The sediment-related blockage data are modelled using homogeneous and non-homogeneous Poisson process models. In most of the analysed areas the inter-arrival time between blockages can be represented by the homogeneous process, but there are a considerable number of areas (up to 34%) for which there is strong evidence of non-stationarity. In most of these cases, the mean blockage rate increases over time, signifying a continual deterioration of the system despite repairs, this being particularly marked for pipe and gully pot related blockages. The physical properties of the system (mean pipe slope, diameter and pipe length) have a clear but weak influence on observed blockage rates. The Bogotá case study illustrates the potential value of customer complaints databases and formal analysis frameworks for proactive sewerage maintenance scheduling in large cities.
由于客户和政治压力不断增加，以及环境法规更加严格，现在在评估下水道系统运行性能时，沉积物和其他堵塞问题是重中之重。沉积物引起的堵塞降低了下水道系统的可靠性，并需要在运营成本相当高的情况下采取补救措施。因此，需要确定下水道系统的哪些部分最需要主动清除沉积物。本文介绍了一个非常长（7.5 年）和空间详细（9658 个网格，每个网格面积为 0.03 平方公里，覆盖近 750 万人口）的数据集，该数据集来自哥伦比亚波哥大的客户投诉数据库。使用均匀和非均匀泊松过程模型对与沉积物有关的堵塞数据进行建模。在大多数分析区域，堵塞之间的到达时间间隔可以用均匀过程来表示，但有相当多的区域（高达 34%）有很强的非平稳性证据。在大多数情况下，堵塞率随着时间的推移而增加，这表明尽管进行了修复，但系统仍在不断恶化，特别是与管道和雨水口相关的堵塞。系统的物理特性（平均管道坡度、直径和管道长度）对观察到的堵塞率有明显但较弱的影响。波哥大案例研究说明了客户投诉数据库和正式分析框架在大城市中进行主动下水道维护调度的潜在价值。
