David L M, Matos R S
LNEC-DH-NES, Laboratório Nacional de Engenharia Civil, Lisboa, Portugal.
Water Sci Technol. 2002;45(3):131-40.
This paper discusses the use of water quality deterministic modelling together with an integrated approach to assess the impact of urban stormwater discharges into ephemeral watercourses, based on the study of a Portuguese catchment. The description of the main aspects, difficulties and benefits found during data collection and model calibration and verification is presented, and the associated uncertainties and errors discussed. Experimental results showed a strong short- and long-term impact of sewer discharges on rivers, and confirmed deposition, resuspension and transport of pollutants as important processes for the water quality. However, the resuspension of riverbed sediment pollutants during storms was probably more significant than the direct impact of the urban discharges. The HydroWorks model was used since it allows for the calculation of pollutant build-up on catchment surfaces and in gully pots, their wash-off, and the deposition and erosion of sediments in sewers. However, it uses several constants, which could not be independently calibrated, increasing the uncertainty already associated with the data. River flows have quite different magnitude from the sewer system overflows, which, together with the difficulties in evaluating river flow rates, makes the integrated modelling approach rather complex and costly.
本文基于对葡萄牙一个集水区的研究，讨论了使用水质确定性模型以及综合方法来评估城市雨水排放对季节性河流的影响。介绍了在数据收集、模型校准和验证过程中发现的主要方面、困难和益处，并讨论了相关的不确定性和误差。实验结果表明，下水道排放对河流有强烈的短期和长期影响，并证实污染物的沉积、再悬浮和运输是影响水质的重要过程。然而，暴雨期间河床沉积物污染物的再悬浮可能比城市排放的直接影响更为显著。使用HydroWorks模型是因为它可以计算集水区表面和雨水口内污染物的累积、冲刷，以及下水道中沉积物的沉积和侵蚀。然而，它使用了几个无法独立校准的常数，增加了与数据相关的不确定性。河流流量与下水道系统溢流的规模差异很大，再加上评估河流流速的困难，使得综合建模方法相当复杂且成本高昂。
