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Mulloon Creek Natural Sequence Farming Demonstration
Co-funded by
Australian Government National Landcare Program & Mulloon Creek Natural Farms
Concept Originator
Peter Andrews
Other Partners
Southern Rivers CMA (SRCMA)
Upper Shoalhaven Landcare
The Natural Sequence Association (Upper Shoalhaven Chapter) Inc.
Important Stakeholders
Department of Environment and Climate Change
Department of Primary Industries
Sydney Catchment Authority
Department of Lands
Palerang Shire Council
Australian Government
The Yuin and the Ngunnawal people
The Upper Shoalhaven community and beyond
Urban water users
Background
On a bleak mid-winter’s day in 2005, Tony Coote invited Peter Andrews to Mulloon Creek Natural Farms to assess his property and to meet a few colleagues. That meeting led to a series of events that now sees a demonstration of his work firmly established at the property.
After the meeting, Tony and Peter quickly agreed to work together to establish a demonstration of his Natural Sequence Farming at Mulloon Creek Natural Farms.
The catchment community was fully consulted starting with Tony’s downstream neighbours.
SRCMA agreed to lead an application to the National Landcare Program to establish an NSF trial at Mulloon Creek Natural Farms. Within a month of that first meeting an application was completed and sent.
The project was approved in January 2007. Major on-ground works began in early April, and occurred in two phases, each taking about a week. During phase one, 8 complexes were built into the creek at the lower end of the floodplain to arrest any further erosion (figure 1) (table 1).
Phase two took place in the first week of September. A further five complexes were constructed in and near the creek within the upper half of the floodplain (figure 1) (table 1).
Further minor works, modifications and maintenance has continued since.
Setting
Mulloon Creek Natural Farms is situated in the headwaters of the Shoalhaven River on the NSW Southern Tablelands. The Shoalhaven flows out to sea through Nowra and supplies Sydney with drinking water via Tallawa dam.
Mulloon Creek catchment itself covers an area of about 800km2. It flows northward for about 40km (linear) before meeting Sandhills and Shiel Creeks then abruptly takes a right turn and spills into Reedy Creek, which then flows into the Shoalhaven.
The upper Mulloon catchment is steep and forested. Agriculture is generally confined to the lower end of the catchment and the small floodplain pockets in the valley. One of these floodplain pockets is on the “The Home Farm” one of Tony’s two Mulloon Creek Natural Farms properties.
Johnson and Brierley (2006) described these floodplain pockets as being partly swampy with a discontinuous channel prior to European settlement. The introduction of European culture saw rapid erosion and incision of these floodplain pockets.
Today a continuous channel extends though “The Home Farm” floodplain and several eroded side channels enter the creek.
Aims
This project aims to: - Reverse erosion (encourage deposition) within the stream and on the floodplain using strategically placed and designed structures and copious vegetation to de-energise and filter high flows.
- Restore the natural hydrology by raising the level of the stream, ultimately re-establishing the functional connectivity between the stream and the floodplain.
- Rejuvenate the biodiversity and fertility in the stream, on the floodplain and more broadly.
(Table 1)
No Name Description
1 Goldney’s Gate Three large boulders arranged in a triangle.
2 Wombat pond Cobble controlled pond. No modifications. Automatic flow monitoring.
3 Peters weir and pond Rock weir supported by large willow tree and Cumbungi. Bank shaping and planting.
4 Weatherstation Crossing Rock baffles below rubble crossing.
5 Willows Crossing Complex Three weirs, two constructed side channels, pond lengthening, two rock baffles and a constructed pond. Bank tapering.
6 Williams’s Wallow Two log and rock weirs, a constructed levy and pond.
7 Triple Ponds Series of three weirs. Bank tapering.
8 Platypus Weir and pond One weir made from rubble and willow branches. Bank tapering.
9 Go Back Way Back Crossing Large side-channel redirected against the creek flow. One constructed pond.
10 Mitchell’s Weir Rock and rubble piled up around a felled willow tree.
11 Porkony’s pond and crossing Rock, cobble, soil and vegetation weir.
12 Hazellbank Cobble, soil and vegetation bank. Further stages planned.
13 Poplars Crossing Rock, logs, rubble and vegetation crossing. Low flow directed through pipe.
14 Wily’s Ripl Limestone outcrop.
15 Pump Shed Weir Rock weir. Flow directed against bedrock.
16 Black Jackie Bedrock controlled pond. Automatic flow monitoring. Monitoring
The biggest concern for downstream landholders is; how will the instream works affect the flow of Mulloon Creek?
With this in mind, automatic flow sensors (measured as pond depth) have been installed above and below “The Home Farm” floodplain (figure 1) . A third sensor has been installed 8km (linear) downstream to measure significant flow on from high flow pulses. These sensors measure depth every half an hour, so they can measure rapid rises and falls in the water level.
Each pond within “The Home farm” floodplain is also manually measured for depth generally weekly and more often during high flows.
A transect of piezometers across the lower part of the floodplain measures depth to groundwater (figure 1).
Other monitoring includes:
• stream form change
• pond ecology
• soil properties
• photographic and video log
• agricultural productivity
Some results so far
Climate and hydrology (see opposite page)
Long-term average rainfall of 700mm a year.
Last ten years below average rainfall. Last twelve months, 473.4 mm. Fourth driest twelve month period in thirty years of rainfall records at Mulloon Creek Natural Farms.
Three major rainfall events occurred in the first year. June – July recorded 150mm of widespread rain filling the whole Mulloon system and recharging groundwater. Next 5 months recorded below average rainfall. All the piezometers and several ponds dried up.
On 28 December a ‘super-cell’ storm broke over the Home Farm - 60mm of rain in less than one hour. A surge of water peaking at one metre was recorded at Black Jackie. Approx 100 mega litres (100 swimming pools) of very turbid water flowed into and through the Home Farm refilling all the ponds for 5km (linear) downstream.
Two smaller storms delivered about 10 mega litres each to the project site during January and February.
A second ‘Super Cell’ broke above the Home Farm boundary on 25 February delivering another 100 megalitres of water in less than an hour. Because all the ponds were close to full, most of the storm surge went straight through the home farm and refilled ponds all the way to Reedy Creek.
Messages
Water level in the ponds reflects the level of the groundwater.
Inflow to the Home Farm has ceased several times. Outflow has never fallen below 100,000 litres per day.
Storm surges rise and fall quickly at the top end of the floodplain but dissipate through the system. The surges have a lower peak at the bottom and tail off more slowly i.e. less water in the short-term more in the long-term.
It took nearly three days for the water from the last pulse to reach Reedy Creek.
Before and after photos of Peter’s pond and weir
1. 31st March 2006. Looking at Peter’s pond towards Peter’s weir.
2. Same shot 4th February 2007
3. 31st March 2006. Overlooking Peter’s pond looking south up the floodplain
4. Same shot 19th June 2006.
5. 27th April 2006. Peter’s weir shortly after construction.
6. Same shot. 26th February 2007.  31st March 2006. Looking at Peter’s pond towards Peter’s weir.  Same shot 4th February 2007  31st March 2006. Overlooking Peter’s pond looking south up the floodplain  Same shot 19th June 2006.  27th April 2006. Peter’s weir shortly after construction.  Same shot. 26th February 2007. Reference
Johnson, P. and Brierley, G. (2006) Late Quaternary river evolution of floodplain pockets along Mulloon creek, New South Wales, Australia in The Holocene 16.5 pp 661 674.
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