Alluvial gully erosion
Alluvial gully erosion
Gully erosion into active river floodplains and terraces (relict floodplains) affects river health and aquatic life, industries, infrastructure and Indigenous cultural activities. As they erode wider and deeper, gullies can make the land unusable for pastoral and agricultural use.
They also carry sediment and nutrients from the floodplains into rivers, creeks, lagoons, estuaries and oceans, affecting aquatic life and their habitat. In northern Australia, gully erosion rates have increased up to ten times since European settlement, due to cattle grazing and land use change (fire/weeds/roads/fences) along river frontages.
TRaCK researchers Jeff Shellberg, Andrew Brooks, and John Spencer from Griffith University have studied the causes and impacts of gully erosion into alluvial soils, which is widespread across northern Australia, and recommend major changes to land management along river corridors.
- Alluvial gully erosion represents a major threat to riparian and aquatic landscapes and agricultural production in northern Australia.
- European land use practices have accelerated the initiation and growth of alluvial gullies, with up to ten times greater erosion rates since European settlement.
- Sediment yields from gullies on floodplains in northern Australia are very high by both Australian and world standards (up to 350 tonnes per hectare per year).
- Gully erosion from floodplain soils is a major source of sediment in northern Australian catchments.
- Once started, gully erosion will continue to increase at current rates unless changes to land management paradigms are made, along with significant rehabilitation efforts.
- Promoting native grass vegetation and limiting soil surface disturbance are the most important defences against alluvial gully erosion.
- Changes to cattle grazing practices, such as fencing cattle away from steep river banks and riparian zones along large rivers, can prevent alluvial gully formation and reduce erosion rates.
- Changes to road and fence locations and maintenance practices can reduce the triggering of alluvial gullies.
- In areas of strategic and cultural importance, rehabilitation tools have been developed to determine the best passive or direct biological, chemical, and physical methods for reducing erosion once it has begun.
- Social, economic, and political issues present major challenges to effectively rehabilitating gully-prone landscapes.
For more information on Gully Rehabilitation and Grazing Land Management, visit the Cape York Water Quality website, or access the following scientific publications by clicking on the links below: