[Viet Nam] Valuing the benefits of blue/green infrastructure for flood resilience, natural capital and urban development in Viet Nam

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Flooding is the most damaging and costly hydrometeorological hazard affecting millions of people globally every year. In Viet Nam, low-lying coastal cities, particularly in river deltas, face increased flood risk and vulnerability due to rapid urban development and climate change. To reduce flood risk in urban areas, the recent decade has seen increased appreciation of the potential of Blue/Green Infrastructure (BGI), such as natural and man-made wetlands, vegetated river banks and restored floodplains, to reduce flood risk and provide additional benefits, such as controlling water pollutants, providing recreational opportunities, improving air quality and increasing resilience to other stressors, such as heat waves and noise pollution. However, despite the growing interest in BGI in a flood risk management context, assessments of the effectiveness and viability of such measures have in the past been mostly piecemeal, focusing on individual impacts of such measures (e.g. flood risk reduction, provision of urban green space). Such sectorial assessments cannot account for the potential trade-offs or complementarities between the multiple impacts of individual installations, let alone whole networks of BGI. Therefore, ValBGI seeks to develop a multidisciplinary, stakeholder-informed assessment framework for the effectiveness of BGI to reduce flood risk and improve urban natural capital. Thereby, the project examines the role of BGI in short- and long-term urban development, with application to the city of Can Tho, Viet Nam. This holistic framework integrates a number of disciplines and does not only follow an interlinked and multidisciplinary research agenda but also advances the academic state-of-the-art in the individual disciplines involved. This includes the engagement of key stakeholders in the research process to co-develop solutions and disseminate evidence to key decision-makers; innovative high-resolution modelling of flooding and BGI at the city-scale; and spatially explicit assessment and valuation of changes in the provision of ecosystem services enabling the quantification of the investment into urban natural capital effectuated by BGI. To achieve these objectives, the project comprises four work packages which function as interlinked components within the multidisciplinary assessment framework: (1) The operational backbone of ValBGI is a work package that establishes a stakeholder group to work alongside the research team from start to end. This component assesses (and when necessary stimulates) the awareness of alternative natural processes-based BGI options among local and regional urban planners and other key stakeholders. (2) A second work package reviews existing flood models for Can Tho and the Vietnamese Mekong Delta and develops a new high-resolution modelling system to assess the effectiveness of selected BGI measures in reducing flood risk. (3) In the third work package, changes in the provision of ecosystem services following the installation of BGI measures will be assessed and mapped. (4) In the fourth work package costs and benefits of BGI measures (in terms of flood risk reductions and improvements of urban natural capital) are quantified by means of valuation, and cost-benefit analyses of BGI scenarios are conducted. The continuous stakeholder engagement in ValBGI ensures awareness for and uptake of the research outcomes by decision-makers to maximise impact of the evidence produced. Furthermore, the holistic approach provides a better understanding of the potential trade-offs and complementarities between flood risk reduction and improvement of natural capital generated by BGI. Exploring all simultaneous impacts of BGI is beneficial in providing environmental managers and urban planners with a complete array of information for supporting planning decisions.