Landscape Rehydration

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I was recently in Charleville and inspired by the landscape rehydration work in the region and the interest in soil health and soil carbon. Southern Queensland Landscapes, Project Officer Glenn Landsberg shared some slides and data on what is happening and has kindly permitted me to share some of that with the RCS audience.

Laser-leveling spreader banks

Using laser levels to create spreader banks

SQ Landscapes says there is 30 million ha of country in the southwest of Qld which could benefit from landscape rehydration. Evolving from various techniques used by multiple groups worldwide and enhanced by local innovations, methods are being developed to suit SW Qld.  This includes mitigating erosion features, spreader banks, strategic timber windrow placement and landscape appropriate grazing practices.

Having successfully worked on water harvesting in one of my past lives in northern Nigeria, I was interested in where the design has got to.

The series of photos below, taken by Glenn, shows part of 20km of different spreader banks used on ‘Maybe Station’, SW Qld. Graded banks use laser technology to maximize effectiveness and minimize cost. They are designed to slow and spread water away from erosion features, back onto floodplains and wetlands and promote recovery of natural ecosystem function.

20km of different styles of cheap spreader banks on Maybe Station

20km of different styles of cheap spreader banks on ‘Maybe Station’

The question which instantly arose for me was – what is the cost : benefit of doing this?

Glenn put up the following slide showing 2,000ha, which had 20km of banks put up to slow the water, taking 13hrs of grader time. This was taken in the Quilpie/Adavale area. The local contractor said it would cost $1,900 to do, so we rounded it up to $2,000 to make the maths easy. Cost =$1/ha.

Carl, an experienced local feed budgeter and grazing chart enthusiast, estimated that 21mm of water held up could produce 30 SDH of carrying capacity. Let’s halve that to 15 SDH to be more conservative and leave at least half. An SDH has a Gross margin of around $1. Therefore 15 SDH is a $15/ha return per ha, provided the domestic stock get to eat it. A 15:1 benefit : cost ratio is an impressive return in anybody’s book.

Water slowly filtering through the maze of gaps in the spreader banks hrs. after a 21mm storm. Normally this water would have disappeared down erosion features minutes after such a storm.

Water slowly filtering through the maze of gaps in the spreader banks hrs. after a 21mm storm. Normally this water would have disappeared down erosion features minutes after such a storm.

The following photo shows the use of timber windrows.

Windrows on 'Farnham Plains', Eulo

Windrows on ‘Farnham Plains’, Eulo

This is a 1.3km windrow placed across a scalded flat on ‘Farnham Plains’, Eulo.

The infiltration data (Landsberg pers com) was also impressive. The infiltration tare where water was held up was 75mm in 3 minutes. Where it was still clay pan, 75mm did not all go in over 13 hours.

There is a lot of landscape throughout Australia where these simple techniques can change the landscape quickly.

However, there are a few risks to consider.

  • Firstly, spreader banks need to be laser levelled to function correctly, allowing water to spread without forming channels or erosion.
  • Secondly, there is little point in reclaiming the landscape if it is then overstocked and overgrazed again.
  • Thirdly total grazing pressure must be controlled, which may mean having fences to allow for that.
  • Fourthly, they may not fill every year, and there will be times when you could wait for the falls to flood the structures.
  • Finally, they will likely need maintenance in the long run.

One of the most brilliant book titles I have come across is “Everything I want to do is illegal” by Joel Salatin. That applies to the following changes in ecosystem health.

Which begs the question – “Why is it illegal to restore landscape function as shown below in so many locations around Australia?”. GO FIGURE. Luckily SQ Landcapes are working in an area where they can do these trials without contravening land management laws, and therefore provide the opportunity to complete such promising research.

Further reading: How to use low profile contour banks to promote ground cover & pasture. Southern Queensland Landscapes.

Authors:
Dr Terry McCosker OAM
Founding Director of RCS

Terry McCosker


Glenn Landsberg
Southern Queensland Landscapes, Project Officer