Assessing sustainable development of flood mitigation projects using an innovative sustainability assessment framework

Sustainability assessments of flood mitigation projects are crucial for achieving sustainable development of floodplains. This article presents the application of an innovative sustainability assessment (SA) framework for flood mitigation projects throughout its life. The research employed a literature review, consultation with experts, and a case study of a flood mitigation project in Australia. The sustainability assessment framework includes five stages: (a) contextualizing the project; (b) SA at the planning and implementation stage; (c) SA during a flood event; (d) SA at regular intervals; and (e) SA during a change or modification phase. The results of the sustainability assessment at the first two stages of the flood mitigation project suggest how the sustainability index (SI) could be used to choose the best design options. Also, the study presents how the achievement toward sustainability of the finally constructed project could be compared with the planned project using the SI score. Sustainability assessment at Stages 3 – 5, carried out with possible scenarios, demonstrates that the project's sustainability could be hindered by the growing number of vulnerable population and property development in the floodplain without an upgrade of the project. The findings suggest the applicability of the SA framework for better decision-making for sustainable flood risk management.

development in the floodplains (Environment Agency, 2004;Plate, 2002). At present, the planning and implementation of flood mitigation projects are largely focused on the design, construction, and the maintenance of the structures. The structures are primarily designed based on the extent of flood mitigation it can provide. The impact of the structures on the environment and socio-economic state is studied, to some extent, in the design and implementation stage only. Studying channges in the enviornmental conditions and social and community dynamics in response to the implemented flood mitigation project could be helpful to evaluate the impact of the project in the floodplain (Environment Agency, 2010;Shah, Rahman, & Chowdhury, 2015). Currently, monitoring and maintenance of the flood mitigation structures are usually conducted over the years after implementation, particularly during a flood event to ensure the functionality of the structure for flood prevention. However, the existing planning process does not adequately consider the long-term socioeconomic and environmental issues related to the performance of the flood mitigation project as well as the long-term sustainability of the floodplain (Department of Natural Resources and Mines, 2014;Environment Agency, 2010;Shah et al., 2015). Therefore, flood risk reduction through structural measures that ensure sustainable development remains a major challenge to planners and policy makers.
Integrating sustainability issues to development programs has received much attention from researchers in recent decades. It has been advocated that the sustainability appraisal or assessment (SA) of a country's policies, programs, and projects could be the best approach to measure how the policies, programs, or projects address the sustainable development issues at the national (macro), regional or program (meso), and local (micro) level (Dalal-Clayton & Sadler, 2014;Devuyst, 2000;Sadler, 2004). Recent literature has also proposed various sustainability assessment approaches, mainly at the national level (e.g. Dashboard of sustainability [Dalal-Clayton & Sadler, 2014]) and regional or program level (e.g. SA guidance for regional and local authorities [Office of the Deputy Prime Minister, 2005], regional sustainability assessment framework for a Portuguese region [Coelho, Mascarenhas, Vaz, Dores, & Ramos, 2010]), with little focus on assessment at the local or individual project level. The national and regional level SA approaches have not been linked to local level projects, although the local level individual projects ultimately impact on sustainable development at the regional and national level (Shah et al., 2015). Within the literature, there are only a few sustainability assessment tools applicable at the project level (e.g. Ugwu, Kumaraswamy, Wong, & Ng, 2006;Varey, 2004), which were mainly applied at the planning stage of the projects to decide on the most suitable options that positively impact on environmental and socioeconomic conditions of the project area. None of these SA tools for individual projects considered SA of the project at the post-implementation stage.
Flood mitigation projects, particularly those including physical structures, have a huge impact on the floodplain, thus an integrated assessment of potential impacts on present and future environmental and socio-economic issues of the floodplain appear critical. In addition to a lack of tools at the project level, there are also very few sustainability assessment tools that have been developed for flood mitigation projects. For example, Department for Environment, Food and Rural Affairs (DEFRA) (2007a) developed a SA guidance for evaluating flood and coastal erosion management policies, plans, and schemes within the United Kingdom. This method uses several indicators for sustainability rankings and other performance measures such as operations and maintenance, environmental impacts, and health and safety to assess alternative options for flood mitigation projects (DEFRA, 2007b). This SA approach was developed only for planning stage, though the report recognized the need for SA at the postimplementation stages throughout the project's life (DEFRA, 2007b).
In summary, the available SA approaches for projects were mainly applicable for the selection between potential alternatives during the planning stage. However, these SA methods do not include modules or components to examine whether the option selected as best alternative in the planning stage would be practically sustainable in future.
Therefore, a comprehensive sustainability assessment approach that can incorporate sustainability issues throughout the whole life of the project including planning, implementation, operation and maintenance, monitoring, and decommissioning/modification stages is warranted.
Given a lack of available local level, lifelong SA methods, Shah, Rahman, and Chowdhury (2017) developed a "Decision support framework for the sustainability assessment of flood mitigation projects" to assess the project's contribution to sustained flood risk reduction as well as its impact on the sustainable development of the floodplain. Subsequently, the objective of this paper is to demonstrate how the proposed SA framework (Shah et al., 2017) can be applicable to flood mitigation projects throughout the entire project life. The paper first briefly outlines the proposed SA framework, and then presents the findings and discussion of the application of the SA framework in a case study flood mitigation project.

| METHODOLOGY
This research has employed a mixed methods approach which includes a review of the extant literature, consultation with experts, and a case study of a flood mitigation project in Queensland, Australia.
The case study project was selected from Australia due to convenice of data collection from ongoing project. However, the findings of this study could be generaly applicable to similar structural flood mitigation projects (e.g. levees or embankments) commonly implemented around the world. The planning and implementation process and sustainability issues during the different stages of project life of the project were determined through a review of project documents and a series of consultations with experts involved with the project. A list of sustainability indicators suitable for the case study project was determined based on the set of indicators provided within the "Decision support framework for the sustainability assessment of flood mitigation projects" (Shah et al., 2017). The sustainability assessment framework (Shah et al., 2017) was then applied throughout life cycle of the case study project. Given the project was implemented recently (2014)(2015)(2016), available secondary data were collected from project documents and the implementing agency (local government authority) and were used for the sustainability assessment of project at the planning and implementation stage. For sustainability assessment at other stages of project life (e.g. during flood event, decommission/ modification stages), the authors have developed scenarios which consider potential future change in the environmental and socio-economic conditions of the floodplain. As future projected values of the indicators are not available, a scenario-based analysis was adopted to demonstrate the applicability of the sustainability assessment framework throughout the project life of the flood mitigation project.

| AN INNOVATIVE SUSTAINABILITY ASSESSMENT FRAMEWORK FOR FLOOD MITIGATION PROJECTS
The following section presents an innovative "Decision support framework for the sustainability assessment of flood mitigation projects" developed by a previous study (Shah et al., 2017). Flood mitigation projects like levees are believed to potentially have adverse impacts on the socio-economic and environmental aspects of floodplains despite their provision for flood mitigation (Sayers et al., 2013). An overview of the sustainability assessment framework is illustrated in Figure 1. Details of the framework and methodological procedures can be viewed in Shah et al. (2017). The framework considers indicator-based susainability assessment method. A list of 25 potential indicators including environmental, social, economic, and policy and instrutional contexts related to flood mitigation project is provided (see further in Section 5.1: Table 1). In this paper, the process of sustainability assessment has been demonstrated through the application of the framework in the case study project and is explained further in the following sections.

| CASE STUDY PROJECT
This study investigates the "Dale Street Flood Mitigation Project" in Queensland, Australia, which was completed by Moreton Bay

| APPLICATION OF THE FRAMEWORK THROUGHOUT THE LIFE OF THE CASE PROJECT
The application of the sustainability assessment framework to the Dale Street Flood Mitigation Project was performed for all five stages of the project life. As mentioned earlier, the project was completed in 2016, the application of the Stages 1 and 2 of the SA framework was carried out with the available data from the project documents provided by the council. Values for some of the indicators, which were not available for the small project area, were assumed based on expert judgement. The detailed calculation process for estimating the sustainability index for the project is provided in Stage 2. The sustainability assessment for Stages 3-5 of life cycle has followed the same calculation process as that of Stage 2.

| Stage 1 of the SA framework: Contextualizing the project (Dale Street flood mitigation project)
In Stage 1 of the SA framework, the context of the Dale Street Flood Mitigation Project was delineated in view of local and regional F I G U R E 1 Overview of the decision support framework for sustainability assessment of flood mitigation projects floodplain. The project aimed to protect residential properties in the flood-prone areas along Dale Street to provide security and convenience for locals, and to reduce the maintenance costs of roads and other utility services. In addition, it was planned to extend the existing community park within the dry detention basin of the project area.
The project was contextualized in view of flood risk reduction, socio-economic, environmental, and institutional settings of the project life cycle, as well as the relationship of the project to the sustainable development policies of Queensland and Australia. In the context of reducing the flood risk, the project will reduce damage to residential buildings and roads (MBRC, 2015). As there are no commercial buildings or businesses or agricultural activities in the project area, the   (Table 1). Further, the maximum and minimum achievable target values (both quantitative and qualitative) for all sustainability indicators were also defined (Appendix : Table A1) so that the positive or negative effects of the Dale Street project on the indicators could be compared during the different stages of the project.
The range between the maximum and minimum target values for each indicator was then classified into five classes: highly negative, negative, neutral, positive, and highly positive impact. Each impact class was assigned with a score of 1-5, where 5 represents a highly positive impact and 1 a highly negative impact (Appendix : Table A1)  and rearranged weight for D1 as 1, for D5 as 1, and for D8 as 3. For Case 2, the replacement of indicator D5 with D8 but keeping the same weight of 2 as with D5. With the value of D8 as 75% (and impact class given in Table A3 of Appendix A), the study estimated the SI for Case 1 as 436 and for Case 2 as 437 (Table 2). This analysis shows how changes in the indicators could be adapted into the sustainability assessment of the The sustainability assessment of the newly modified project should start from Stage 1 and continue through to Stage 4 of the SA framework.

| DISCUSSION AND CONCLUSIONS
This research illustrated the process of applying an innovative sustainability assessment framework for flood mitigation projects. The decision support framework for sustainability assessment developed by Shah et al. (2017)  whether the selected best alternative would be sustainable or not in the post-implementation stage, which is a prime concern in the performance of a sustainability assessment (DEFRA, 2007a(DEFRA, , 2007b.  Since the assignment of weight to the sustainability indicators depends on the decision-makers and other stakeholders, as well as on the contextual background of the project (Mitchell, 1996), there could be various combinations of indicators and weights in the final SI score.
The uncertainty of values of some indicators could add complexity in SI estimation, but this is unavoidable as all complex modelling exercises contain some assumptions (Zhu, Bai, Xu, & Zhu, 2011).
Further research is required to conduct a sensitivity and uncertainty analysis of the indicators and their impact on the calculation of the SI score. Also, sustainability assessment of the project with various possible scenarios at different stages of project life cycle could be explored to minimize the uncertainty and reliability of the assessment, especially for large-scale flood mitigation projects, which are implemented in several phases and involve many stakeholders. This sustainability assessment approach could be applied in other government development projects. In addition, an integrated asset management system could be developed integrating the data generated through the sustainability assessment of individual projects, which may minimize the resource requirement for long-term monitoring of the projects.