Managing Erosion in the Willandra Lakes Region World Heritage Area, Australia
John Leys1, Tom Barrett2, David Bye3, Mal Ridges2, Sandy Booth4, Dan Rosendahl
1NSW OEH, Gunnedah, Australia, 2NSW OEH, Armidale, Australia, 3NSW OEH, Buronga, Australia, 4NSW OEH, Parramatta, Australia
The Willandra Lakes Region World Heritage Area (WLRWHA) is 300,000 hectares with roughly a 60% falling on private pastoral properties and rest within Mungo National Park. The Willandra is listed for World Heritage due to its unique ability to understand a palaeo-wetland environment within the arid zone as well as it place within the global human narrative.
The number one threat to these values is erosion. Ironically, it was erosion that revealed the World Heritage Values, now great efforts are dedicated to suppress it. Causes of erosion include grazing pressure, wind and water. The NSW Office of Environment and Heritage's, WLRWHA and Science Division Staff have been working to create GIS models and use multi-criteria analysis to map areas prone to erosion and put in place mechanisms to arrest it and measure the efficacy of such systems.
This paper will present the analysis of two methods to control erosion: 1) movement of stock watering points away from areas of archeological significance, and 2) fencing of areas to reduce stock access to areas of archeological significance.
Landsat fractional ground cover data was analysed for the period 1998 to 2014 at 17 sites where erosion control actions were implemented. Results indicate that for water point sites 6 sites improved in ground cover, while at fenced sites 1 sites improved. The success of the recovery of a site was dependent on the soil type. Sandy soils tended to show greater improvement than clay soils. Soils that had been severely degraded, that is scalded, did not show signs of recovery.
Recovery of ground cover levels took three to five years. In some cases, cover levels that were 30% below the cover level of the surrounding land type recovered to being 10% greater. This recover has been sustained over the last decade through the Millenium drought.
This project has demonstrated the efficacy of these two erosion control methods in protecting the soil from erosion, and thus protecting the values of the WLRWHA. These methods have increased the ground cover to levels above that required to control wind erosion in areas of archeological significance in the WRLWHA.