McIlhatton T D, Ashley R M, Tait S J
Department of Civil Engineering, University of Liverpool, Brownlow Street, Liverpool.
Water Sci Technol. 2005;52(5):143-50.
For more than a decade, research carried out in Scotland has investigated the movement of sediment in sewers and the associated pollutant release. Pollution by discharges from combined sewer overflows can adversely affect watercourses, particularly those in urban areas. Solids and dissolved contaminants, many derived from in-sewer deposits during a storm event, can be especially significant. This phenomenon can occur during events known as 'foul flushes'. In combined sewers these typically occur in the initial period of storm flows, when the concentration of suspended sediments and other pollutants is significantly higher than at other times. It has become apparent that much of the suspended load originates from solids eroded from the bed. The 'near bed solids' which are re-entrained into the flow, together with solids eroded from the bulk bed, account for large changes in the suspended sediment concentration under time varying flow conditions. This paper describes some of the methods employed to investigate the solids eroding in combined sewers during peak flow events. The work examined the potential for sediment re-suspension under high flow conditions both in the laboratory and in the field.
十多年来，苏格兰开展的研究一直在调查下水道中沉积物的运动以及相关的污染物释放情况。合流制下水道溢流排放造成的污染会对水道产生不利影响，尤其是城市地区的水道。固体和溶解污染物，其中许多源自暴雨期间下水道内的沉积物，可能影响尤为显著。这种现象可能发生在所谓的“污水冲刷”事件中。在合流制下水道中，这种情况通常发生在暴雨径流的初期，此时悬浮沉积物和其他污染物的浓度明显高于其他时段。很明显，大部分悬浮负荷源自河床侵蚀的固体物质。重新卷入水流中的“近河床固体物质”，以及从河床主体侵蚀的固体物质，在随时间变化的水流条件下，导致悬浮沉积物浓度发生大幅变化。本文介绍了一些用于研究暴雨径流事件期间合流制下水道中固体物质侵蚀情况的方法。这项工作在实验室和实地考察了高流量条件下沉积物再悬浮的可能性。
