In recent decades, rapid urbanization has resulted in a growing urban population, transformed into regions of exceptional socio-economic value. By removing vegetation and soil, grading the land surface and saturating soil air content, urban developments are more likely to be flooded, which will be further exacerbated by an anticipated increase in the number of intense rainfall events, due to climate change. To date, data collected show that urban pluvial flood events are on the rise for both the UK and China. This paper presents a critical review of existing sustainable approaches to urban flood management, by comparing UK practice with that in China and critically assessing whether lessons can be learnt from the Sponge City initiative. The authors have identified a strategic research plan to ensure that the sponge city initiative can successfully respond to extreme climatic events and tackle pluvial flooding. Hence, this review suggests that future research should focus on (1) the development of a more localized rainfall model for the Chinese climate; (2) the role of retrofit SuDS (Sustainable Drainage Systems) in challenging water environments; (3) the development of a robust SuDS selection tool, ensuring that the most effective devices are installed, based on local factors; and (4) dissemination of current information, and increased understanding of maintenance and whole life-costing, alongside monitoring the success of sponge cities to increase the confidence of decision makers (5) the community engagement and education about sponge cities.

Climate change has seen increased pressures put on the existing ageing flood mitigation infrastructure. As a result, over recent decades there has been a shift from traditional hard-engineered approaches to flooding to more sustainable methods that utilise nature-based processes in order to slow flow, store water and increase infiltration. Doing so has resulted in a range of different nomenclature for such techniques, particularly in the rural environment. This paper takes a critical review of such terms to draw parallels in the different approaches, with the aim of developing a more unified, consistent approach to flood management. Furthermore, links have been drawn with the urban environment, where Sustainable Drainage Systems (SuDS) are used as a sustainable approach to urban flooding. The findings from this review have identified a series of issues that result from the current UK approach of differentiating between urban and rural flood risk, with funding often given for Natural Flood Management (NFM) projects separately to SuDS, with little integrated thinking from source to sea. Hence, the review suggests (1) a greater consideration of scale, focusing on the catchment as a whole, is required to ensure a more holistic approach to flood management, under the phrase “sustainable catchment-wide flood management”, to ensure that the focus shifts from NFM (rural) and SuDS (urban), to a more integrated catchment-wide approach; (2) the development of robust policy and regulatory framework, to ensure that such an approach is more widely adopted; (3) a greater consideration of the long-term costs is also required, with future research needed on the long-term maintenance costs of different methods; (4) the development of modelling approaches that can simulate flow at a range of spatial and temporal scales, to support stakeholders, such as local authorities, flood risk engineers and government agencies when considering flow not only in rural areas, but also to understand the impact beyond the immediate area around the scheme.

Vegetated swales are a popular sustainable drainage system (SuDS) used in a wide range of environments from urban areas and transport infrastructure, to rural environments, sub-urban and natural catchments. Despite the fact that vegetated swales, also known as grassed swales, have received scientific attention over recent years, especially from a hydrological perspective, there is a need for further research in the field, with long-term monitoring. In addition, vegetated swales introduce further difficulties, such as the biological growth occurring in their surface layer, as well as the biological evolution taking place in them. New developments, such as the implementation of thermal devices within the cross-section of green SuDS for energy saving purposes, require a better understanding of the long-term performance of the surface temperature of swales. This research aims to contribute to a better understanding of these knowledge gaps through a descriptive analysis of a vegetated swale in Ryton, Coventry, UK, under a Cfb Köppen climatic classification and a mixed rural and peri-urban scenario. Precipitation and temperature patterns associated with seasonality effects were identified. Furthermore, a level of biological evolution was described due to the lack of periodical and planned maintenance activities, reporting the presence of both plant species and pollinators. Only one event of flooding was identified during the three hydrological years monitored in this research study, showing a robust performance.

This paper reviews the devices suitable for building scale application and then outlines three case studies, two from Coventry, UK and one from Valencia, Spain. The first assesses the potential to retrofit an extensive green roof to the Frederick Lanchester Library, Coventry University. Costings are given, the structural strength of the building is investigated and various benefits of its installation, including potential to sequester and store carbon, are assessed. The second reports part of the AQUAVAL Project, Spain, whereby an extensive green roof was retrofitted to half of a school roof and porous concrete retrofitted to a pavement. Preliminary monitoring results show expected benefits, including attenuation of the storm peak and increased time to peak. The third case study using WinDes^® software compared a conventionally drained new-build housing estate with a Sustainable Drainage Systems train of porous paving, bioretention and swales. Stormwater volume was reduced by ∼20% and peak flow by >250 L s^–1. Addition of extensive green roofs to all buildings increased these differences and delayed return to baseflow conditions reflecting water stored in the management train components.

Sustainable Drainage (SuDS) improves water quality, reduces runoff water quantity, increases amenity and biodiversity benefits, and can also mitigate and adapt to climate change. However, an optimal solution has to be designed to be fit for purpose. Most research concentrates on individual devices, but the focus of this paper is on a full management train, showing the scale-related decision-making process in its design with reference to the city of Coventry, a local government authority in central England. It illustrates this with a large scale site-specific model which identifies the SuDS devices suitable for the area and also at the smaller scale, in order to achieve greenfield runoff rates. A method to create a series of maps using geographical information is shown, to indicate feasible locations for SuDS devices across the local government authority area. Applying the larger scale maps, a management train was designed for a smaller-scale regeneration site using MicroDrainage^® software to control runoff at greenfield rates. The generated maps were constructed to provide initial guidance to local government on suitable SuDS at individual sites in a planning area. At all scales, the decision about which device to select was complex and influenced by a range of factors, with slightly different problems encountered. There was overall agreement between large and small scale models.