Rivers and wetlands provide water for human use and support rich and biologically diverse ecosystems in arid and semiarid landscapes (drylands). We sat down with Dr Tim Ralph from the Department of Environmental Sciences to understand why the conservation of these areas is important and learn about his research into why Botswana might hold the answers.
In a few sentences can you explain a little about what your work involves?
My research is focused on understanding how and why rivers and wetlands are created and modified over time, and how biophysical processes cause change in fluvial landscapes.
Take us back to the beginning – where did it all begin?
I first started my research about 15 years ago as a student, and I have visited the Macquarie Marshes and other wetlands each year since. The marshes themselves are iconic – the beauty and expanse of the landscape are striking, as is the stark contrast between the wet and dry parts of the wetlands.
Why is this work important?
This work is critical for understanding, conserving, and managing rivers and wetlands in a long-term context. For example, the Macquarie Marshes are very dynamic – they are ever-changing – and several other rivers and wetlands in dry landscapes around the world are similar to them. My research seeks to explain how quickly biophysical changes are occurring in systems like the Macquarie Marshes and the Okavango Delta in Botswana, and what factors are controlling, or moderating, them.
You have recently returned from a field trip to Okavango Delta, Botswana. Tell us a little bit about your work there.
The field trip was mainly funded by a Macquarie University Research Development Grant and the project was titled “Sediment and carbon in ‘wetlands and drylands’: understanding long-term biophysical change in iconic ecosystems”.
A key factor that causes significant change in rivers and wetlands is avulsion, the process of channel relocation on the floodplain that can lead to a river abandoning its course (i.e. channel failure) in favour of a new one (i.e. channel formation). This type of channel change often modifies wetlands with rich habitats, biodiversity, and biomass.
This project seeks to better understand the key forces that influence channel failure and formation in the Panhandle region of the Okavango Delta. The style and frequency of avulsion have implications for the distribution of water, sediment and nutrients in the system, which influence aquatic productivity, vegetation growth and decay, and long-term carbon storage in these iconic wetlands.
So what’s next?
I have another research trip coming up in December, when I will travel to the Nile River, Egypt to work as part of a team with Dr Yann Tristant from Macquarie’s Department of Ancient History to investigate the links between environmental change and human use of the temple at Dendara.