Gully erosion – the use of computer based landscape evolution models to predict initiation, growth and stabilisation

Gully erosion is recognised as a significant environmental issue. It affects grazing, croplands as well as rangelands. Of particular interest here are mining landscapes which are comprised of unconsolidated waste material that has little or no economic value. These landscapes are new systems with little nutrients and plant growth potential and the materials are often highly erodible and prone to gullying. Many empirical and physical models have been developed to understand gully initiation, growth and stabilisation. Here we demonstrate the use of computer based landscape evolution models to quantify the gully process. These models use a digital elevation model to represent the landform and allow the landform to evolve through time. The models can operate at sub-hourly through to millennial time scales. The landform (and resultant gully) can be visualised and rates of movement quantified and erosion rates calculated.  Different land surface properties such as vegetation cover, armour as well as climate variability can be investigated at the hillslope, catchment and landscape scale. These models offer a huge advance in visualisation and quantification of gully evolution. The models have been used across a wide range of materials and climates and will be demonstrated using several mining case studies. Of particular interest for the mining industry is how surface properties change through time as armouring and weathering occurs and vegetation establishes. Model strengths will be highlighted and areas where advances, particularly field data needs will be discussed.