The effect of flow on nutrients on wetland habitats: "Floodplain/Wetland Processes in the Lower Balonne system"
Dr Martin Thoms
This project aimed to determine the role of different habitats in the Lower Balonne floodplain/wetland system in trapping carbon and nutrients from floodwater and the extent of these exchanges during floods. The project objective was to determine flow requirements and land management criteria for semi-arid floodplain/wetlands by addressing the following specific questions on the Lower Balonne system:
- What are the main floodplain/wetland habitats (physical compartments) within the Lower Balonne system, and what is their relative extent?
- What are the rates of long-term storage of carbon and nutrients within these habitats, and have they changed over time with water resource development and changing floodplain use?
- What is the inundation character of the different habitats, in terms of the timing, frequency and duration of flooding, and has this changed with water resource development in the catchment?
- What are the effects of flooding on carbon and nutrient availability in different habitats, and the magnitude of carbon and nutrient stripping from flood flow through habitats?
- Has water resource development influenced the transfer of carbon and nutrients between the river and the floodplain/wetland system?
Data collection and analysis included:
- Habitat mapping and classifications;
- Habitat statistics;
- Pre-flood sampling;
- Sediment core sampling and dating of cores;
- Analysis of historical hydrological data;
- Analysis of first flood;
- Monitoring of second flood season;
- Chemical analysis; and
- Hydrological modelling.
Fourteen remotely sensed images from between 1988 to 1999 were used to characterise the floodplain environment's soil conditions and different vegetation communities. This was ground-truthed through field work. The geomorphology of the river systems below St George were further characterised following the method of Van Nerk (1988). Extensive experimental work was also conducted on the floodplain to determine the role of nutrients and carbon for soil fertility and vegetation dynamics.
This project provides a better understanding of the physical and ecological processes in large semi-arid floodplain/wetland systems which is important to on-ground decision-making.
The project provides an excellent example of how to examine the ecological and physical processes of a large wetland area. This examination includes both hydrology and geomorphology along with ecological processes. An understanding of the research process would be useful to academic courses in natural resource management and other ecology courses, as well as to wetland managers and researchers.
A copy of the final report is available from the University of Canberra web site .
Principal researcher's contact details:
Dr Martin Thoms
CRC for Freshwater Ecology
University of Canberra
CANBERRA ACT 2601
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