Structural flood damage and the efficacy of property-level flood protection
Authors: Chung Hau Ching Phyllis , Adeyeye Kemi 
Published: July 2018

Purpose
The purpose of this paper is twofold: first, to investigate the flood impact on a detached dwelling based on physical attributes related to the positioning, form and orientation of the house, and second, to investigate the effectiveness of property-level protection (PLP) to mitigate the direct structural damage of the house and the degree of floodwater ingress within the house.

Design/methodology/approach
The methods included modelling and simulation within the ANSYS Fluent® computational fluid dynamics software. Flooding scenarios with constrained parameters using theoretical modelling methods/tools were used to test the research hypotheses. Therefore, the results obtained will match the what-if scenarios considered if/based on the standard equations and assumptions made in the idealised model.

Findings
It was found that the position, orientation and form of an individual dwelling with brick and block construction informs the impact of the applied pressure on the structure and water ingress. Increase in pressure on the structure was noted from 0.3 m. All examined PLP mitigated the risk of structural damage if applied in consideration with other interventions e.g. mortar sealing. The use of non-return valves could potentially increase the pressure on the structure, but was also found to be effective in reducing water ingress. Findings should be considered in conjunction with the assumptions and exceptions of this study.

Research limitations/implications
The limitations of this study are that the findings are based on an idealised model of a single detached house, with no landscape obstruction to the watercourse. This mathematical approach concerned with developing the normative models may therefore not fully describe the real-world complex phenomena. But it provides the first vision and an objective basis to answer the questions under study, and to propose usable outputs. Flooding caused from internal sources (e.g. bursting of pipes, roof leaks) or seepage from the ground and moisture through the walls were excluded. Building content was not modelled.

Practical implications
Common property-level flood interventions are typically tested to mitigate water ingress to the house. This study extends this approach to include the prevention of structural damage to the external walls; this can help to avoid the indiscriminate use of property-level flood prevention solutions without full understanding of their degree of effectiveness or impact on the building’s structural integrity. This study is practically significant because it provides outputs and means to examine which intervention(s) are better for delivering flood protection to a standard brick/block detached house type. This knowledge is highly beneficial for relevant stakeholders who can use it to deliver effective property-level flooding resilience measures.

Originality/value
The study provides useful insights for property owners and building professionals to explore suitable, cost-effective single property-level protection against flooding. Furthermore, the effective implementation of interventions can be used to achieve a customised, “fit for purpose” resilience retrofit.