Mangrove forests provide valuable coastal habitats but also provide a natural form of coastal flood protection and a host of other services. However, many of these mangrove forests are threatened by coastal development and groundwater pumping-induced subsidence, among other natural and human changes. Part of the challenge is that mangroves are extremely choosy about their habitat, and need just the right combination of tidal submergence and mud to take root. If these habitats are thrown out of balance by people or natural causes, it becomes hard for new mangrove seedlings to grow there and sustain the forest.
To make happier places for the mangroves to develop, different kinds of coastal fences/dams have been proposed. The general principle is that waves and currents are attenuated or blocked by the fences, which makes a nice quiet area behind them for mud to accumulate and mangrove propagules to take root. What impact do these structures have on the coastal “conveyor belt” transporting mud and propagules? Enter Nirubha Raghavi Thillaigovindarasu!
Just before Christmas, Raghavi successfully defended her thesis, “Mangrove-Sediment Connectivity in the Presence of Structures Used to Aid Restoration“. Beginning with a numerical model of a site in Indonesia to simulate the motion of rivers and tides, she then applied the SedTRAILS model to visualize and interpret the pathways of sediment and mangrove propagules as they journeyed along the coast. By adding structures to her model, she was able to demonstrate how this trapping behaviour has an influence in the vicinity of a structure but also up to a kilometer away.
The story of this research began several years ago. Dr. Alejandra Gijón Mancheño tackled the topic of such structures extensively in her PhD, and when she finished we both wondered: is there a way that we could combine her work with my research on sediment pathways to better understand and optimize mangrove restoration? Last year, Femke Bisschop stepped up to the plate for her MSc thesis, modelling mangrove propagules and sediment pathways. Her work made us curious as to how these pathways would be influenced by coastal structures, and that’s where Raghavi came in.
Raghavi jumped on this project with great gusto and carried out a great deal of complex numerical modelling. She further developed our SedTRAILS model and ultimately led to several useful results that can be used to better inform mangrove restoration initiatives. Many exciting new questions await answers in the wake of her research.
Big congratulations to Raghavi, who will start a new position as Junior Consultant and Researcher at Deltares in the coming weeks. I am very proud of her and look forward to many future collaborations!
As something of a creative exercise prompted by a discussion with colleagues about ChatGPT, I pasted Raghavi’s abstract into ChatGPT and told it to write a poem in the style of ee cummings (after trying several other poets). It went a little heavy on ballet metaphors (though I liked “propagules pirouette“), and I’m not sure it’s possible to include “Delft3D” eloquently, so think it was largely a failed experiment. Conclusion: just go read Raghavi’s thesis, I promise it’s much better!
mangrove dreams
wetland whispers
in tropical hushecosystem ballet
coastal guardians
carbon poets decline
paints a sorrowful blushrestoration’s dance
a waltz among misunderstood reeds
a pas de deux with failure’s stingpermeable dams
architects of hope
sediment sighs
waves bow
a tranquil offeringa system’s secret waltz
currents, waves
sediment ballet
Demak: a stage for nature’s playnested models whisper
Delft3D-4
a hydrodynamic ballet
SedTRAILS, the poet
tracing pathwayshydrodynamic whispers
a quiet hush
currents bow
waves waltz
impermeable structures steal the gazesediment pathways
a silent plea
imported whispers
coastline sighs,
a dance with potential retreattests unfold
impermeable grace
sediment’s kisspropagules pirouette
trapping in the wind’s duet
Demak’s hope
a ballet resetconclusion whispers
coastal structures sing
sediment and propagule’s ring
a varied dance
nature’s offering
Coastally Curious 