Every hour an expanse of coastal land equivalent to a football field disappears from the Mississippi river delta. The Mississippi River Delta is only one of the numerous deltaic systems which are at danger due to both climate change, and human activities.
Deltas are home to half a billion of people, are among the most productive ecosystem on earth, and constitute the main food source for many nations thanks to their fertile soils, and fisheries activities.
River deltas form when sediments carried by rivers enter the sea, and form fans of sand or mud which give rise to complex, colourful, and spectacular depositional environments
River Deltas are vulnerable to both anthropogenic and natural changes such as sea level rise, changes in sediment supply, hurricane activity, and urbanization.
Researchers all around the world are collaborating and putting great efforts to better understand the hydrodynamic and morphological behaviour of river deltas. In this regard numerical models are useful tools and in combination with field data and aerial images allow investigating the evolution of river deltas at a range of time scales as well as under different climate change scenarios.
Aims and objectives
The goal of this project is to investigate the hydrodynamic and morphological behaviour of river deltas under different external forcing. Special focus will be given to sea level rise, and changes in sediment supply. The Ganges-Brahmaputra-Meghna Delta in Bangladesh (Figure 2) will be the main test case in combination with more idealizedscenarios which will be used to obtain results more general and extendable to river deltas all around the world. Research questions include, but are not limited to:
- How the morphology or river deltas will change under different sea level rise scenarios?
How riverine sediment input affects the hydrodynamic and morphology of river deltas (e.g. effect of turbidity currents, effect of starvation or abundance of riverine sediment)?
These research questions will be investigated and discussed to understand their wider implications for the future of coastal environments from a human and ecological perspective.
A combination of numerical models and field data will be used. The hydrodynamic, sediment transport, and morphological models Delft3D, and FVCOM are widely tested, and have been developed to study coastal and riverine environments.
In this project existing and extensively validated model configurations, and model setup will be adopted (e.g. Figure 2). Model performance, and predictions will be further tested by means of additional hindcast simulations, and by comparing model outputs with existing dataset, and Landsat images. Specifically, Landsat images will be used with the dual goal of: i) verifying model performance in relation to past morphological changes, ii) identifying possible relationships between morphological changes of river deltas (e.g. channels connectivity, avulsion, aerial extension, etc.), and present rates of sea level rise, and changes in sediment supplies. Such relationships will help to further test, and evaluate the predictive capabilities of computer models. Once model performance is tested, the numerical investigations will be also used as exploratory tools more than for purely deterministic predictions. The use of numerical models as exploratory tools will allow determining the exact physical mechanisms responsible for existing morphological behaviours, and extend considerations to a wider range of natural environments [e.g. Murray et al., 2002, 2003].
- Formulation of key questions based on literature review, and available data.
- Familiarization with the numerical models, and model runs.
- Execution of numerical experiments aimed at exploring the specified research questions.
- Evaluation of models performance and predictions
- Data analysis, and results interpretation: Results will be critically analysed and discussed to provide useful indicators and parametrizations aimed at identifying the role of climate change and different external forcing on the evolution of river deltas.
Results dissemination: research outcomes will be disseminated through presentations at international conferences, workshops, as well as the publications of scientific papers and a final report.