Modelling Future Urban Growth Scenarios in the Context of SSPs and Ecosystem-Based Adaptation to Address Flood risk in Huế Vietnam.

The city of Huế has experienced significant urban growth, driven by population growth, economic development, and rural-to-urban migration. This expansion has intensified the city’s vulnerability to flooding, a recurring natural hazard exacerbated by climate change and inadequate urban planning. Despite growing awareness of the importance of ecosystem-based adaptation in urban flood management, there remains a gap in understanding how these strategies can be effectively integrated into urban planning processes, particularly in the context of rapidly growing cities like Huế. This study therefore aims to investigate the feasibility and efficacy of incorporating ecosystem-based adaptation measures into urban growth modeling to enhance flood resilience. The study integrates ecosystem-based adaptation (EBA) strategies and an empirical model into a CA-based model (UGM) to explore potential future urban growth scenarios by 2050 and their impact on flood risk in Huế. Three different scenarios based on the shared socio-economic pathways (SSPs 1, 2, and 3) are developed in the context of the rate of urbanization, restricting urban growth in flood-prone areas, land areas with tourism opportunities (tourism is a major economic sector in Huế), and high opportunities for ecosystem services in the city. Scenario 1, aligned with SSP 1, portrays future urban growth characterized by robust ecosystem-based adaptation measures. Scenario 2 (SSP2) reflects the current trajectory, incorporating partial ecosystem-based adaptation measures, while scenario 3 (SSP3) depicts limited ecosystem-based adaptation. Across all scenarios, urban land use expands through inner densification and extension of existing urban areas. However, the topography of the province, flanked by mountains in the west and the sea and lagoon in the east, constrains future urban growth. Notably, regardless of the scenarios, urban expansion is anticipated in the low-lying plains of the province, exacerbating the city’s exposure to flooding.