2 3The rapid growth of cities under modern development pressure has resulted in surface water flooding becoming an increasing hazard and future climate change uncertainties may exacerbate this threat still further: retrofitting sustainable drainage systems to attenuate stormwater runoff has been advocated as part of an integrated solution required to address this problem. Many of these adaptations not only enhance a community's resilience to flooding, but may also offer additional benefits in terms of improved environmental amenity and quality of life. The evidence base for sustainable drainage is critically evaluated in respect of the implications for urban planning, as applied to existing housing stocks and business properties in urban areas worldwide. It is concluded that this approach can make a substantial contribution towards urban resilience as part of an integrated approach to managing extreme storms. This will be of interest to urban planners and designers considering the implementation of integrated flood risk management.

With the increasing densification in urban settlements the economic and social disruption caused by pluvial flooding events globally is significant and growing. Furthermore these problems are compounded where many cities are located in areas where climate change predictions are for increased rainfall frequency and/or intensity. One possible solution is the wide scale retrofit with green roof technology as a means of mitigating stormwater runoff in urban settlements. However, it is not known currently where the most effective location for and siting of the retrofitted green roofs in a city or town would be. Moreover, the number of and type of green roof required to reduce pluvial flooding is unknown.This paper describes a proof of concept framework for an assessment of the potential to reduce pluvial flood hazard through the retrofit of green roofs combining an evaluation of the retrofit potential of office buildings in the Central Business District (CBD) with state-of-the-art urban rainfall inundation modelling. Using retrofit scenarios for Melbourne CBD commercial buildings built between 1998 and 2011 and the rainfall profile of the February 2011 event, the modelled depths of flooding were compared. The results show that the potential to mitigate extreme events via retrofit would be enhanced by consideration of buildings within the wider catchment.

In the context of anticipated climate change, particularly the frequency and intensity of rainfall events likely to affect the UK in future, it is becoming increasingly important to understand the ways in which people perceive, and therefore respond to, natural hazards such as flood risk. Behavioural models, incorporating key predictive factors, are sought by the policy-making bodies, in order to develop effective interventions for improving community resilience to extreme weather events. An examination of factors relevant to flood risk perception is presented, including the degree of exposure to the threat; concepts such as 'controllability' and 'dread' associated with different hazards; and the wider issues of perceived responsibility, blame-shifting and ontological security. The complex interactions between the factors, together with some UK-specific issues, pose challenges for the development and testing of any model seeking to explain and predict the behaviour of people in the UK exposed to flood risks. Some innovative techniques, capable of modifying aspects of the perception of risk, which can be incorporated into community engagement initiatives, are also discussed.

One of the drivers for improving resilience to flooding at property level (also known as adoption of a 'water entry strategy') was demonstrated by the overtopping of hard engineered flood defences across Cumbria, UK during 'Storm Desmond' in December 2015. Although the uptake of water exclusion strategies (also termed 'flood resistance) is gradually improving in the UK, the longer term resilience options that permit water entry are less popular. Findings from an evidence assessment of the barriers and drivers to uptake of low-cost water entry strategy options are presented. Evidence was collected using a Rapid Evidence Assessment of published materials, semi-structured interviews and workshops with professionals, and a series of case studies of properties that had been adapted to flood risk. Factors leading to successful implementation are identified and illustrated by case study material from homes and small businesses. Water entry and water exclusion approaches were found to be seen as two methods used as part of an integrated approach that can bring about important co-benefits such as improved thermal efficiency and lower energy bills.

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