University of Twente Student Theses


Decreased resilience of mangroves stressed by human interference

Willemsen, P.W.J.M. and Horstman, E.M. and Dohmen-Janssen, C.M. and Friess, D.A. and Borsje, B.W. (2015) Decreased resilience of mangroves stressed by human interference.

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Abstract:Biophysical feedback mechanisms are essential to maintain mangroves. These mechanisms facilitate sediment deposition during periods of tidal flooding and stabilize mangroves. However, human interference (e.g. sediment starvation and coastal squeeze) affects these biophysical interactions. This paper shows the impacts of human interference, i.e. sediment starvation and coastal squeeze, on the biophysical interactions in mangroves. Field data of hydrodynamics and sediment dynamics were obtained in a fringing estuarine mangrove in the Straits of Johor, located at the northern shores of Singapore. An accurate depth-averaged process-based numerical model was developed in Delft3D, showing reasonable approximations of flow velocities and deposition rates. Simulations with this model provided insight in the instantaneous response of the mangrove when sediment starvation and coastal squeeze were reduced. The model results show increased deposition rates within the mangrove when sediment supplies were restored. A reduction of the coastal squeeze by extending the intertidal area in the inland directions results in increasing flow velocities and deposition rates as well. A comparison between these scenario runs and the current state of the mangrove shows a decrease in biophysical interaction and even a total loss of the contribution of vegetation to the stability of the current state mangrove. The human interference, contributing to sediment starvation and coastal squeeze, has evidently decreased the mangrove’s resilience. More importantly, relieving these human induced stresses, found to enhance sediment deposition rates, facilitates an increased resilience to future changes such as sea-level rise.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
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