Modelling of flood flushing in a tributary constrained by barrages.

Purpose – Flood flushing is one natural cleansing capability of a natural river channel to wash away in-stream pollutants and debris. The purpose of this paper is to explore the flood flushing restriction in a tributary due to its regulated main river channel between two barrages. Design/methodology/approach – In the absence of detailed data, a concerted effort of computer river modelling is conceptualized to represent possible flushing conditions. Findings – Regulation schemes of barrages are deduced to interrupt the natural tidal and river flow interaction zones and thus impede river flushing capability. Practical implications – Modelling of barrages' operating modes suggested that though the man-made structures are unable to replicate natural flood flushing, proper operations offer a secondary option to achieving the desired water quality objective in a constrained tributary. Originality/value – Studies on minor tributary of modified main-stem river are few. The attended tributary-trunk relationships carry the credibility of this paper. [ABSTRACT FROM AUTHOR]