Rangelands NRM Blog, News & Resources

Upper Gascoyne pastoralists explore sieve filter structures

[May-June 2016]

Land managers in the Upper Gascoyne recently met to learn about a variety of techniques for controlling erosion.

Six stations and representatives from the Department of Parks and Wildlife (DPaW) and the Department of Agriculture and Food (DAFWA) attended a sieve structures erosion control workshop at Carey Downs Station on 28-29 April, organised by the Upper Gascoyne LCDC and supported by Rangelands NRM through funding from the National Landcare Programme.

Rangelands NRM Regional Landcare Facilitator Kane Watson said sieve structures are the simplest and most cost effect ways of controlling erosion.

“Pastoralists from the Upper Gascoyne feel current guides lack the practical detail for pastoralists to implement and install them with confidence,” he said.

Rangeland rehydration expert Dr Hugh Pringle presented his knowledge of existing sieve filter structures across Australia and Namibia with a variety of materials and explored options with participating pastoralists.

“Ultimately, we hope pastoralists attending this workshop will go on to trial affordable technologies to manage varying erosion types and water flow and trial a variety of techniques to control erosion,” Mr Watson said.

He said this workshop was to build base knowledge of the project participants and explore options as a group.

The group visited priority areas identified through an ESRM (Environmentally Sustainable Rangelands Management) Plan on Carey Downs to discuss how to read the landscape and identify optimum placement of erosion filters structures.

The workshop also included a group session on reading the landscape for placement as well as ideas for erosion control approach.

“We need to work out how to recover from erosion and regenerate large areas at low cost” Upper Gascoyne LCDC President Jason Hastie said when making introductions for the commencement of the workshop.

“It will be interesting to see how the group takes the learnings from this workshop and develop them into the Rangelands NRM facilitated project to build sieves on their properties,” Mr Watson said.
Some points on sieve construction that came out of the workshop (compiled by UG LCDC) were:

  • For any soil conservation efforts to work, excessive grazing pressure must be addressed.
  • Suspension sieves are very effective filters and can be used from small gutters to the largest rivers and high flow situations.
  • Sieve structures are best installed perpendicular (straight across) to the flow.
  • Filters must filter, not dam, unless they are really strong.
  • Filters are best located at critical control points in the landscape. (See page 42 of the Rangelands Rehydration Field Guide.)
  • Bush is effective and can be used in small and large situations. Your chainsaw is your friend. Plain wire can be used to anchor brush in place.
  • Starting high in the landscape is always best, but plugging the bottom with a sieve is good idea too.
  • Anything appropriate to hand can be used to make sieve structures from.

“It was a really valuable couple of days, it made me reconsider my approach,” pastoralist Matthew Hammarquist said. “I’ve seen other possibilities and built confidence to proceed with sieve erosion works at Mt Augustus”.

“We’ve been looking at some rangelands in pretty poor shape,” said Harry McKeough from Carey Downs said. “We are exploring methods to fix them up, and I’ve picked up a lot that I can now put in place. I’ve learnt aspects of reading the rangelands and identifying my problem areas”.

“Hugh Pringle has a fantastic understanding of landscape processes,” David Pollock from Wooleen Station said. “It’s fabulous to have someone with that depth of knowledge available”.

Images:
(Left) Harry McKeough explaining his understanding of water flow at Carey Downs (©K.Watson)
(Right) Looking over a ringlock sieve (©K.Watson)