Modeling Climate Change Impacts On Coastal Resources With Enhanced Simulation Model Mantra
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Date
2021-03
Authors
Kh’ng, Xin Yi
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Universiti Sains Malaysia
Abstract
Accelerated sea level rise (SLR) and precipitation change in response to climate change is well underway, the impacts of which call for appropriate climate action SDG 13. The associated increase in surface seawater inundation and subsurface saltwater intrusion will reduce the availability of fresh groundwater due to permanent salinization of groundwater. Further, increased levels of soil salinity and decreased freshwater inputs may alter coastal ecosystems by facilitating the establishment of plants with higher salinity and flooding tolerance. This thesis focuses on the modelling and analysis of climate change impacts on the availability and quality of coastal groundwater as well as on the potential changes in coastal vegetation. For this purpose, the simulation model MANTRA is enhanced and used in this thesis. The hydrology-salinity-vegetation model MANTRA was developed by coupling the vegetation competition model MANHAM and groundwater flow and solute transport model SUTRA. SUTRA is first verified against standard density-dependent flow benchmarks for the purpose of ensuring correct understanding and implementation of SUTRA. Further simulation and analysis are then performed to provide insights on the response of an atoll island’s fresh groundwater lens to SLR and changes in precipitation. The potential of harvesting rainwater to mitigate the impact of SLR on coastal aquifer is also explored. To examine the impacts of sea level rise on coastal groundwater and vegetation, MANTRA is enhanced to include inundation and water stress response functions for application to Pantai Acheh of Penang. For application to Coot Bay Hammock of Florida Everglades, MANTRA is further enhanced by incorporating a third competing vegetation. The response of coastal wetlands to SLR is found to be largely dependent on the topography of the study area and the availability of suitable areas for vegetation migration landward. Model simulation suggests that fresh groundwater is non-viable in Penang Island. Further, a projected 1-m rise in sea level is expected to result in the loss of up to 21% of mangrove coverage in the study site at Pantai Acheh of Penang Island. In Coot Bay, the buttonwoods and halophytic prairie could eventually be squeezed out, followed by irreversible landward replacement of freshwater hammocks by mangrove communities. The modelling insights from this research would be useful for future sustainable management of coastal resources and development of coastal community’s resilience towards climate change impacts.
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Mathematics