- Title
- Modelling wetland dynamics under climatic and human pressures
- Creator
- Sandi Rojas, Steven Gerardo
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2018
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Simulation of wetland vegetation dynamics requires the integration of adequate hydraulic, vegetation and sediment transport descriptions in order to provide more realistic predictions of vegetation changes over time. Human interventions on wetland systems are a common practice around the world, but the impacts resulting from flood regulation and attenuation have often been excluded from the analysis of wetland dynamics due to oversimplifications of the water flow description. Climate change impacts are also predicted to contribute to trends of global wetland loss because of changes in rainfall-runoff patterns, more frequent droughts, increases in temperature and sea level rise. This thesis presents the development of two frameworks for simulating wetland dynamics in Australia under anthropogenic and climate change pressures: one for tropical coastal wetlands and one for semiarid freshwater wetlands. The models implement hydrodynamic simulations in order to describe the characteristics of the water regime. The basic assumption is that time aggregated descriptors of the water regime, such as flood frequency, flood duration, range of water depth, hydroperiod, and others, are the main drivers of vegetation establishment and survival. The study of both sites provides a contrast that shows the applicability of the methods used in the thesis. In the coastal wetland site, inflows are dominated by the tide, but in the Macquarie Marshes inflows are delivered by the Macquarie River. The magnitude of the area of analysis is another major difference between the two systems: the coastal wetland site has a relatively small area (1.24 km²) whereas the Macquarie Marshes is an extensive freshwater wetland (322 km²). The framework developed for coastal wetlands was applied to a heavily controlled site typical of south-east Australia in order to study the vulnerability of wetland vegetation to submergence under accelerated sea-level rise rates and different management scenarios. Eco-geomorphic accretion mechanisms were included in the analysis of coastal wetlands with a soil surface elevation model. The framework developed for floodplain freshwater wetlands was applied to an ecologically important site: the Macquarie Marshes. Floodplain simulations included the response of wetland understory and forests over a series of 23 years where significant deterioration was reported after an extended drought period. Two simplistic climate change scenarios were also studied to predict changes in vegetation by the year 2030. The simulation of coastal wetlands revealed higher rates of wetland loss when attenuation effects are included in the wetland evolution framework. Based on these results, previous global estimates might be underestimating coastal wetland losses. Simulation of the Macquarie Marshes predicts an increased succession of wetland understory to terrestrial vegetation under a dry climate change scenario. The simulated conditions almost reach the severe deterioration experienced at the breaking of the millennium drought.
- Subject
- wetlands; eco-geomorphic modelling; eco-hydraulic modelling; climate change; inland wetlands; coastal wetlands
- Identifier
- http://hdl.handle.net/1959.13/1387412
- Identifier
- uon:32603
- Rights
- Copyright 2018 Steven Gerardo Sandi Rojas
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 24 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 619 KB | Adobe Acrobat PDF | View Details Download |