Uncertainties and constraints on breaching and their implications for flood loss estimation
- 15 June 2005
- journal article
- Published by The Royal Society in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
- Vol. 363 (1831), 1423-1430
- https://doi.org/10.1098/rsta.2005.1576
Abstract
Around the coasts of the southern North Sea, flood risk is mediated everywhere by the performance of natural and man-made flood defences. Under the conditions of extreme surge with tide water levels, the performance of the defences determines the extent of inland flooding. Sensitivity tests reveal the enormous increase in the volume of water that can pass through a defence once breaching is initiated, with a 1 m reduction in sill elevation doubling the loss. Empirical observations of defence performance in major storm surges around the North Sea reveal some of the principal controls on breaching. For the same defence type, the maximum size and depth of a breach is a function of the integral of the hydraulic gradient across the defence, which is in turn determined by the elevation of the floodplain and the degree to which water can continue to flow inland away from the breach. The most extensive and lowest floodplains thereby ‘generate’ the largest breaches. For surges that approach the crest height, the weaker the protection of the defence, the greater the number of breaches. Defence reinforcement reduces both the number and size of the breaches.Keywords
This publication has 1 reference indexed in Scilit:
- Catastrophe loss modelling of storm-surge flood risk in eastern EnglandPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2005