Many of the Soils for Life case study participants are applying techniques which are based on the natural hydrology of the Australian landscape and how nature evolved and sustained immensely productive and resilient biosystems despite Australia being such a dry continent. By understanding these hydrological processes, resilient water systems can be designed and restored.
Restoring hydrological processes
Australia’s landscape used to be characterised by ‘in-soil’ reservoirs. Complex microbial ecologies maintained soft deep soils which allowed for infiltration and retention of rainfall into well-structured subsoils. These in-soil reservoirs then leached any salt to depth and slowly recharged and sustained what were typical reed covered billabongs, chains of ponds, meandering waterways and fully functioning floodplains. As a result, most of Australia’s inland rivers did not discharge rainfalls to the sea, but recharged aquifers or created highly productive inland deltas and extensive wetlands and intermittent lakes.
With the introduction of grazing across the Australian landscape, riverside vegetation was grazed and repeated stock access caused the banks to become eroded. Gradually, rainfall would wash into what was becoming a gully and only in significant rainfall events would it flow over the banks, each time washing away more soil. Confined to a gully, water flow continues to erode and gullies become more deeply incised.
A primary step by many of the case study participants in more effectively managing water on their property has been to fence off water courses to prevent stock access, or limit access through time-controlled planned grazing, to reduce further erosion of river banks. Combined with the establishment of leaky weirs, as drawn from Natural Sequence Farming methods, this enables regeneration of vegetation and restoration of riparian areas to function as they did prior to the introduction of grazing. Read more about how this works on the Earth Integral website.
Water management in action
On Tallawang on the NSW North West Slopes and Plains, Craig Carter was concerned about the poor condition of the land – erosion, soil compaction and impoverished pastures – and the severely eroded creek and gullies. The banks of the creek and tributaries were incised, with gullies and contour banks further draining water off the property, increasing susceptibility to drought. The creek had eroded down to a base of basalt rocks and stones for its length. Craig sought advice from Peter Andrews, to design leaky weirs to restore natural water cycles.
Mainly constructed from dead trees, later in conjunction with plantings of native reeds, these structures created a ponding effect and retarded water flow. Six years on, previously bare soils and gravel beds are covered with regenerating plants and considerable siltation is evident as the vegetation traps sediment carried from upstream. The creek on Tallawang is now a ‘chain of ponds’, and while inflow varies with rainfall, outflow is constant due to improved water retention in the soil and subsequent hydrological processes.
Left: The river on Tallawang used to be typified by an exposed basalt rock base.
Right: Downstream weirs have resulted in silt build-up and regeneration of vegetation along the banks
On Tallawang, existing contour banks in higher country were also modified, by blocking them at intervals, to form swales that retain and more effectively use water in the upper parts of the landscape. This process has enabled surface water to infiltrate higher in the landscape, thus maintaining the quality and quantity of the diverse perennial pastures longer in the drier times.
Similar techniques applied to the landscape in some of our other case studies include...
On Jillamatong NSW, Martin Royds has shallow drains radiating out from weirs to divert water from the waterway across the paddock.
The Joyces have employed Keyline design principles to contour water away from gullies and as required to dams on Dukes Plain, QLD.
As a result of the regenerative practices applied on Tallawang, the property has become significantly wetter along the upper and mid slopes with increased palatable vegetation later in the drier seasons. Wells that were empty on Craig’s arrival to the property are now full. Previously dry soils along the creek flats are now swampy meadows and wetland plants that did not exist on the property prior to the commencement of the work are in abundance.
Tallawang provides a great example of how rainfall can be made available to be used effectively where it falls, rather than being run off due to poor ground cover or eroded creek lines. Read more of Craig’s story in our Tallawang case study.
Next week we’re going to have the first of our guest blog posts by Charlie Maslin of Gunningrah , who has also achieved some amazing results on his property by actively managing to maximise his received rainfall.
The Soils for Life Team