Supporting decision-making for channel conveyance maintenance

Supporting decision-making for channel conveyance maintenance.
Roca, M.and Houlbert, I. and Henri, A.
In: FLOODrisk 2016, 18-20 October 2016, Lyon, France. (2016)

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Abstract:Flood risk management agencies spend a large amount of their budgets maintaining the conveyance capacity of river channels. Vegetation and its overgrowth is one of the main factors influencing channel capacity. Sediment deposits can also impact watercourse conveyance by reducing flow area. Maintenance works such as vegetation cutting, dredging and desilting aim to maintain or improve channel conveyance capacity. Failure to guarantee the adequate capacity of watercourses during flood events exposes communities and critical infrastructure to severe damages. Despite the undesirable consequences associated with flooding, it is rare that sufficient funds are made available to undertake all necessary activities. In the face of limited budgets, flood risk managers must take difficult decisions in order to decide how and where limited resources should be invested. This paper presents a national scale approach to identify the strategically important watercourses where conveyance related works produce the greatest benefit. This is done identifying watercourses where maintenance works may have a potential to positevely maintain or increase conveyance capacity and watercourses where the attribution of area or receptors benefiting is important. Assembling together this information produces a picture of the strategic lengths of watercourse to be maintained. For example, maintenance works may have a very positive impact in one particular watercourse, reducing effectively water levels and increasing conveyance capacity, but without modifying the flood risk of adjacent properties and thus, not producing any benefit. The paper discusses the tools and models used in the approach, the necessary data inputs, its quality requirements and the best metrics to report the maintenance work performed and its benefits. The approach has been develop for the Environment Agency in United Kingdom to inform the benefits of its annual maintenance programme so the results of the application of the approach in England are presented. The final aim of the methodology presented is to support the decision-making process of flood asset managers ensuring a proactive flood risk-based management approach.
Item Type:Conference or Workshop Item (Paper)
Subjects:Floods > River management
Floods > General
ID Code:1305
Deposited On:18 May 2016 14:26
Last Modified:18 Jan 2017 13:15

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