| Summary: | There is a lack of practical decision support tools useful for a rapid assessment of the potential of ecosystem services when retrofitting permeable pavements in urban areas that either feature existing trees or should be pla nted with trees in the near future. There is also a need for a geospatial decision support tool for different professions such as drainage engineers and urban planners, which is useful for a quick assessment of the potential of ecosystem services when retr ofitting sustainable drainage systems ( SUDS ) in urban areas Therefore the aim is to develop a decision support tool for choosing the best possible options for the retrofitting of su stainable urban drainage system techniques using novel ecosystem service variables and modify it to include a reflection of the confidence level of the assessor to minimise uncertainty , and weighting factors that will reflect the pr ofessional background of the stakeholder s to reduce professional bias . This tool was developed and used to assess 100 sites in Greater Manchester with retrofitting potentials including Brownfield sites . The introduced weighting factors helped to narrow down the choices further. Since the retrofitting of SUDS , especially permeable pavements , and other urban development projects usually involve areas where there are already existing mature trees, further studies were carried out on the damage characteristics of urban tree species on urban structures including permeable pavements, impermeable pavements, kerbs, roads and retaining walls. This was conducted on a different 100 sites also in Greater Manchester. Further studies were also carried out about public acceptance of the urban tree species using pictures taken of trees from the Westonbirt N ational Arboretum. The result s of the ‘ecosystem service’ approach were compared with those of traditional ‘community and environmental ’ approach developed by CIRIA. A comparison with the traditional approach of determining community and environment variab les indicates that permeable pavements are generally a preferred SUDS option regardless of the professional perspectives . The introduced w eighting factors made the tool lend itself to be used by stakeholders of varying professional backgrounds. The results of the comparison of the different approaches showed that the ‘ecosystem service’ approach gave a rather more thorough and precise assessment and will give a less misleading choice of SUDS techniques. In comparison to common public opinion, sta tistically significant differences between social scientists and the general public for the estimation of land costs using the non - parametric Mann - Whitney U - test were found. It was also surprising to find no significant differences in the estimation of hab itat for species by civil engineers and xviii ecologists. Permeable pavements combined with urban trees received relatively high scores, because of their great potential impact in terms of water and air quality improvement, and flood control, respectively. The r esult of the assessment of damages to structures by urban tree species revealed that Norway maple, Lime, Common Ash and Sycamore dominated Greater Manchester, and showed that certain tree species are better suited for certain structures either beca u se of the damage or the nuisance that the trees cause . Impermeable pavements were subject to the highest number of damage from trees (44%), followed by permeable pavements and kerbs (22% and 19%, respectively). Trees planted close to impermeable pavements will c ause more damage to the structure compared to those planted close to permeable pavements under the same conditions. Wild cherry, large leaved lime, horse chestnut and hawthorn may are the best recommended trees for use alongside most roads and SUDS structu res as they have least potential to damage structures. However, horse chestnuts produce lots of litters with their conkers. From aesthetics point of view, sycamore was the most aesthetic tree all - round the year . This study therefore suggests best tree spec ies for permeable pavements and other related structures, and its outcomes are likely to lead to more combined permeable pavement and tree systems in the urban landscape, which are beneficial for humans and the environment. It will help urban developers in choosing the most suitable trees for the right urban environment. It will also help to save money in maintaining infrastructure such as roads and pavements. Keywords : Sustainable urban drainage systems; Ecosystem services; Permeable pavements; Expert system; Different professions; Stakeholders; Uncertainty; Urban trees; Urban structures, Structural damage.
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