Mangrove forests can provide a nature-based solution to mitigate increasing flood risks and adapt to rising sea levels. Mangroves attenuate wind waves and storm surges, but they can also recover from storm damage and adapt to sea-level rise through the combined trapping and production of sediments (Temmerman et al., 2023).
The functionality of mangroves is fundamentally different compared to traditional dikes (Figure 1). Whilst the flood protection capacity is a predictable parameter for dikes, excessive wind and wave forces during tropical storms can damage mangroves and erode the forest floor. Changes in mangrove forest width and density are critical to their flood protection functionality, yet thresholds to storm damage and post-storm recovery rates are unknown (Gijsman et al., 2021). The successful implementation of mangroves to protect coastal communities requires an understanding of these dynamics and a shift towards mangrove restoration and management strategies that combine flood risk reduction with enabling mangrove resilience.
Figure 1 – Fundamental differences in attenuation capacity (functionality) and adaptability (persistence) between mangroves and dikes.
The aim of this project is to quantify thresholds to mangrove failure as well as the consecutive rates of mangrove recovery. The proposed research focuses on the east coast of the Philippines which is frequently hit by typhoons. The project comprises two distinct steps:
1. We will analyse temporal changes in the normalized difference vegetation index (NDVI) from Landsat imagery of all mangroves across the Philippines over the past 20-30 years. Human-driven mangrove loss due to conversion to other land-use functions will be masked. Decadal trends in mangrove extent and density will be associated with local rates of sea-level rise. Sudden event-based drops in mangrove extent/density will be associated with recorded wind speeds, water depths and inundation durations of preceding typhoons.
2. For areas with a clear storm-impact, we will identify the rate of post-storm recovery (NDVI increase), either natural or through restoration. Based on our data and local knowledge, field study sites will be selected representing varying storm impacts and consecutive recovery (i.e. no recovery, slow recovery, fast recovery, assisted natural regeneration, planting). We will collect field data at these sites to quantify the associated vegetation recovery and forest floor elevations (Pradisty et al., 2025).
This project is funded by the 4TU Resilience Engineering Center. The project will be executed in close collaboration with an MSc student from ITC, who will be focusing on the remote sensing component of the research. Your work will be focusing on the identification of the drivers for mangrove damage and decline (wind speeds, water depths and inundation durations of preceding typhoons), as well as the quantification of the post-storm recovery of the mangroves and their associated ecosystem services.
References
- Gijsman, Horstman, van der Wal, Friess, Swales & Wijnberg (2021). Nature-based engineering: a review on reducing coastal flood risk with mangroves. Frontiers in Marine Science, 8(825).
- Pradisty, Schlund, Horstman & Willemen (2025). Estimating canopy height and aboveground biomass in tropical mangrove restoration areas through multisource remote sensing. Ecological informatics, 92, 103522.
- Temmerman, Horstman, Krauss, Mullarney, Pelckmans & Schoutens (2023). Marshes and Mangroves as Nature-Based Coastal Storm Buffers. Annual Review of Marine Science, 15(1).
other relevant information
This project entails data collection in the field. Please be aware you would need to be willing and able to travel to the Philippines. Funding is available and field data collection will be supported by local partners, but conditions in the field may be harsh.
Supervision
Are you interested in this assignment? Contact the Master thesis coordinator.
