Peter Hazell is a longtime local landcarer and was the first Landcare Coordinator in the Upper-Shoalhaven district (sometime last century). Owing to his affable and level-headed nature, he has always been a popular contributor to the Landcare community. In-between family life and managing 1000 acres on the Mongarlowe River, plus developing his own homestead not far from Braidwood, Pete currently works as a project coordinator for the Mulloon Community Landscape Rehydration project. This catchment-wide project involves multiple landholders near Bungendore, NSW. It aims to implement and scientifically assess aspects of Natural Sequence Farming and has been enthusiastically embraced by the local community.
One thing Natural Sequence Farming is consistently associated with is ‘Landscape Rehydration’ using techniques which slow runoff and spread flood waters across valley-fill floodplains. I asked Pete to provide us with an overview of what might be expected from the Mulloon project and to explain how any outcomes will be scientifically monitored. Here, he discusses what this catchment-community project hopes to achieve and why.
Landscape assessment at Mulloon
by Peter Hazell
Just before Christmas Peter Andrews, some landholders, and I undertook initial onground assessment and planning work in the Mulloon watershed. Over three days we visited five properties. We plan to do at least another 17 days over the next 6 months. Our three days out were also used to test methods for documenting discussions at each location.
The high resolution 2014 imagery (<1m) acquired for the project is a valuable base layer. This image (Figure 1) was taken in January 2014, which if you remember was very hot and dry. Because the imagery has an infrared band, which highlights green vegetation, it means that there is good contrast between areas that are photosynthesising and areas that are not.
Photosynthesis is how solar energy is converted into biomass. It is the primary mechanism which gives rise to virtually all life on the planet. But plants convert less than 0.1% of the solar energy that reaches the surface of the planet into biomass. The rest (up to 1,000 watts/m2) is converted into other forms of energy, such as heat.
On a sunny day, the flux of solar energy falling on 1km2 of ground may be equivalent to the power generated by a large nuclear power plant (1,000 Megawatts).
Therefore, how the remainder of the solar energy, not converted into biomass, is managed while within the Earth’s atmosphere (180,000,000 Gigawatts) is of vital importance, especially on a hot day.
Most of the solar energy that is reflected from a dry surface is converted into what is called sensible heat – heat we can feel. However, from a green vegetated surface up to 80% of the solar energy is converted to latent heat, energy absorbed when water evaporates, or transpires from a plant (latent heat means that for each unit of energy that is absorbed in water vapour there is no change in temperature.) (Figure 2).
One of the aims of the Mulloon Community Landscape Rehydration project is to increase the green surface area of the Mulloon Watershed. So when it is hot and dry, there is plenty of green surface area buffering the landscape against extreme energy fluxes and, as Peter Andrews would say, producing a product at the same time, i.e. biomass.
Intact landscapes can maintain their greenness (and their coolness) when it is hot and dry for extended periods (Figure 3). The Mulloon Community Landscape Rehydration Project hopes to show that an eroded landscape can rebuild and therefore re-green.
Kravcik, M. et al (2007) Water for the Recovery of Climate – A New Water Paradigm. Web book http://www.waterparadigm.org/download/Water_for_the_Recovery_of_the_Climate_A_New_Water_Paradigm.pdf. (large file, 14MB)
Note: If you have any questions or comments regarding the Mulloon Creek project or any other aspects of Pete’s discussion feel free to post them in the comments below. Alternately, you can send an email to email@example.com and we’ll pass on your contact details.
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