Land clearing

When land is cleared in Australian environments, native plants with deep and extensive root systems are usually removed.  Without roots to stabilize the soils, erosion is often the result. In addition the plants that would normally soak up the water are no longer there and so the buffering capacity of the soil is reduced if large amounts of rain fall quickly.  Erosion poses the greatest problems where urban developments are taking place in the local council area.  Not only does it affect the land but will adversely affect the waterways if nearby.  More on this in a later entry.

There are a number of types of erosion.  Those most likely to affect the local area are described below.

Sheet erosion is the uniform removal of soil in thin layers by the forces of raindrops and overland flow. It can be a very effective erosive process because it can cover large areas of sloping land and go unnoticed for quite some time. Sheet erosion can be recognized by either soil deposition at the bottom of a slope, or by the presence of light colored subsoil appearing on the surface. If left unattended, sheet erosion will gradually remove the nutrients and organic matter which are important to agriculture and eventually lead to unproductive soil.

Rill erosion is the removal of soil by concentrated water running through little streamlets, or headcuts. As soil removal continues or flow increases, rills will become wider and deeper

Classical gullies are an advanced stage of channel erosion. They are formed when channel development has progressed to the point where the gully is too wide and too deep to allow machinery or livestock to safely cross. These channels carry large amounts of water after rains and deposit eroded material at the foot of the gully. They disfigure landscape and make land unfit for growing crops.

Streambank erosion can occur in 2 ways.  It can be caused by recreational boats producing bow waves that reach the shore and cause damage. It can also be the result of altered water flows which occur when land is cleared and developed.  Look at the following entry for more information.