As climate change intensifies the frequency of extreme weather events, researchers from the Indian Institute of Technology Bombay (IIT Bombay) have found that mangroves play a crucial role in protecting coastlines from tsunamis and storm surges. Their study highlights how emergent coastal vegetation acts as a natural bio-shield, significantly reducing the force of waves and debris impact on coastal structures.
The research, led by Prof. Behera from the Department of Civil Engineering, used experimental and numerical methods to evaluate how mangroves mitigate tsunami-induced debris impacts on infrastructure. The team employed Smoothed Particle Hydrodynamics (SPH) modeling, a computational method that simulates fluid behavior, to assess interactions between water, vegetation, and debris.
“Nature is supreme, and we must work with it, not against it. Coastal defense systems should align with natural processes like waves, currents, and sediment transport,” said Prof. Behera, advocating for sustainable disaster mitigation strategies.
Mangroves as Natural Bio-Shields
The study focused on emergent vegetation, which includes plants rooted in the soil but with stems and leaves above water. Among these, mangroves proved to be the most effective, thanks to their sturdy roots and rigid stems, which help reduce wave energy. The research highlighted the Bhitarkanika mangroves in Odisha, which have consistently protected coastal regions from annual cyclones.
Conversely, floating and submerged vegetation were found to be ineffective, as they were either washed away or failed to dissipate wave energy.
Simulating Tsunami Impact
The researchers built a scaled-down coastal replica in a large water tank, using a dam-break flume to simulate tsunami-like waves. Sensors recorded debris impact forces, while accelerometers tracked movement speed. The SPH simulation compared two vegetation types:
- Rigid Staggered Vegetation (RSV) – mimicking strong mangrove roots
- Tilting Staggered Vegetation (TSV) – representing plants that bend under waves
Results showed rigid vegetation reduced debris impact by 96%, compared to 89% with tilted vegetation.
A Sustainable Coastal Defense
The study suggests planting rigid emergent vegetation as a cost-effective, eco-friendly solution to protect coastal areas from tsunamis and storm surges. Beyond flood protection, mangroves also act as carbon sinks, contributing to India’s net-zero emissions goal.
These findings encourage policymakers and engineers to adopt nature-based solutions for sustainable coastal disaster mitigation.
