The Appraisal of Environmentally Sensitive Options for Flood Alleviation Using Mathematical Modelling

Abstract

SYNOPSIS A Study of the river Colne from Rickmansworth to its confluence with the river Thames at Staines was commissioned to examine the flood risk and alleviation possibilities. Holistic appraisal of the catchment involved a comprehensive assessment of environmental resources concurrently with hydrological analysis and construction of a one‐dimensional computational hydraulic model of the complex river, canal, and lake system. Model prediction of flood areas and depths allowed the potential flood damage to be assessed throughout the valley. An iterative process to derive the best practical environmental option was carried out interactively by the multi‐disciplinary team. This process was made possible by the swift analysis of alternative options provided by the river model. The nine local authorities and many environmental interest groups involved were consulted throughout, and advised on the formal and public consultation required to complete the study. The environmental framework and model will provide a test‐bed for the detailed design, construction, operation, and post‐investment phases. The model has been used already in the assessment of significant development planning proposals.