Land characteristics and management factors involved in sheet and rill erosion

Processes involved:

Sheet and rill erosion occur when the forces due to rain-fall, flowing water and gravity overcome the co-hesion and weight of the soil particles/aggregates.

Processes involved are:

detachment of exposed soil by
- raindrop impact
- surface flow

transport by
- rain splash
- surface flow

deposition

Surface flow occurs on any sloping surface when the rainfall rate exceeds the infiltration rate.

Of site effects include: increased sedimentation and run-on in streams and on lower lands.

	Land characteristics affecting processes	Factors affected by land characteristics	Management factors that modify land characteristics
Vegetation	- structure, percent surface cover (including litter) - leaf area, rooting depth and perenniality	Exposure of surface soil Intensity of raindrop impact Infiltration/run-off ratio Velocity of surface flow Transpiration and hence infiltration rate and volume of surface flow	All aspects of the vegetation are affected by selection of species and control of biomass by practices such as cultivating clearing trafficking fertilising grazing trampling harvesting burning
Climate	- rainfall intensity/duration - seasonal rainfall/evapotranspiration regime	Intensity of raindrop impact Volume of water exceeding infiltration rate and hence volume of surface flow Soil water content and hence infiltration rate and volume of surface flow
Geology	- permeability of rock or unconsolidated sediments	Soil water content and hence infiltration rate and volume of surface flow
Topography	- microrelief - slope degree and length - slope and landform shape - position in landscape	Infiltration/run-off ratio Velocity of surface flow Volume and velocity of surface flow Tendency to concentrate surface flow Volume of run-on	Contour cultivating, contour banking and strip cropping reduce slope length and affect microrelief
Soil	- profile permeability - depth and water-holding capacity - size/weight of surface particles/aggregates - cohesion of surface particles/aggregates, including tendency to slake and disperse - tendency to surface seal and hydrophobicity - percent stone cover	Infiltration rate and hence volume of surface flow Infiltration/run-off ratio Detachment and transport Detachment Infiltration rate and hence volume of surface flow Infiltration/run-off ratio and velocity of surface flow	The above management practices controlling biomass affect soil organic matter content, which in turn affects all listed soil characteristics except surface rock Direct soil compaction and disruption by trampling, trafficking and cultivating affect soil permeability, water-holding capacity and size/weight and cohesion of aggregates

Aldrick, J.M. et. al. (1988). A study of the Land in the Catchment of the Gippsland Lakes. Department of Conservation Forests and Lands, Victoria

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