Kashefipour S M, Lin B, Harris E, Falconer R A
Environmental Water Management Research Centre, Cardiff School of Engineering, University of Wales, UK.
Water Res. 2002 Apr;36(7):1854-68. doi: 10.1016/s0043-1354(01)00396-7.
In recent years, considerable investment has been committed to sewerage infrastructure and new sewage treatment plants in the catchment surrounding an estuarine basin along the north-west coast of England. Although this capital investment has resulted in a marked reduction in the input of bacterial loads, relatively high counts of faecal indicator organisms are still being encountered in the coastal receiving waters, and the local bathing waters continue to fail on occasions to comply with the European Community (EC) Bathing Water Directive (1976) mandatory standards. Details are given herein of a comprehensive modelling study aimed at quantifying the impact of various bacterial inputs into the estuary and surrounding coastal waters on the bathing water quality. The model domain includes the coastal area and the entire estuary (namely the Ribble) up to the tidal limits of its tributaries. Faecal coliforms have been used as the main water quality indicator organisms. The numerical model developed for this study combines a depth integrated two-dimensional coastal model and a cross-sectionally integrated one-dimensional river model, and is capable of predicting water surface elevations, velocity fields and faecal coliform concentration distributions across the entire model domain. The hydrodynamic model was calibrated using water level and velocity measurements from three surveys and then validated against measured data from three other surveys. In order to predict the faecal coliform concentration distributions, variable faecal coliform decay rates were used, i.e. different values of decay rates were applied to the coastal and riverine waters, for day- and nighttime, and for wet and dry weather conditions. The maximum and minimum decay rates used were 2.32/day and 0.71/day for the dry and wet weather surveys, respectively. The model was then applied to (i) assess the impact of previous discharge strategies and investigate the effectiveness of future capital investment works and (ii) predict the impact of a range of strategic options, including: the effects of adding UV treatment, constructing storm water storage tanks and incorporating various combined sewer overflow (CSO) discharge scenarios for different weather conditions.
近年来，英格兰西北海岸一个河口盆地周边集水区在污水基础设施和新污水处理厂方面投入了大量资金。尽管这笔资本投资已使细菌负荷输入显著减少，但在沿海受纳水体中仍会遇到相对较高数量的粪便指示生物，当地浴场水域有时仍不符合欧洲共同体（EC）《沐浴水指令》（1976年）的强制标准。本文详细介绍了一项综合建模研究，旨在量化各种细菌输入河口及周边沿海水域对浴场水质的影响。模型区域包括沿海地区和整个河口（即里布尔河）直至其支流的潮汐界限。粪大肠菌群被用作主要的水质指示生物。为本研究开发的数值模型结合了深度积分二维沿海模型和横断面积分一维河流模型，能够预测整个模型区域的水面高程、速度场和粪大肠菌群浓度分布。水动力模型利用三次测量的水位和速度数据进行了校准，然后根据另外三次测量的实测数据进行了验证。为了预测粪大肠菌群浓度分布，使用了可变的粪大肠菌群衰减率，即在白天和夜间、潮湿和干燥天气条件下，对沿海和河流水域应用不同的衰减率值。干燥和潮湿天气测量中使用的最大和最小衰减率分别为2.32/天和0.71/天。然后将该模型应用于：（i）评估先前排放策略的影响并研究未来资本投资工程的有效性；（ii）预测一系列战略选择的影响，包括：增加紫外线处理的效果、建造雨水储存池以及纳入不同天气条件下的各种合流制下水道溢流（CSO）排放情景。
