Module 5: Water Erosion Flashcards
What is the process of water erosion?
Detachment, transport, deposition.
What causes water erosion?
What are the effects of water erosion on soil functions?
What are measures to prevent and resolve water erosion?
The main goal is to prevent soil erosion at the start. This can be done by four types of measures.
1. Structural measures: terracing, stone walls
2. Vegetative measures: cover crops, mulch, agroforestry
3. Agricultural measures: contour ploughing, no-till ag
4. Management measures: grazing management, prescribed fire
What percentage of the world’s arable land has become unproductive due to soil erosion in the last 40 years?
30%
What percentage of land degradation is directly attributable to erosion (wind and water)?
84%, water = 56%, wind = 28%.
What two types of water erosion are there?
- Infiltration excess overland flow/horizontal overland flow
- Saturation excess overland flow/
What is a synonym for surface run-off?
Overland flow.
What are causes of soil detachment?
1.Raindrop impact
2. Flowing water
3. Trampling by livestock or people
4. Tillage
What is sediment?
Eroded soil.
What are the five forms of soil erosion?
- Interrill/sheet erosion
- Rill erosion: 30cm deep and 50cm wide.
- Gully erosion: depth and width >50cm
- Stream/river bank erosion
- Mass movement: creep erosion and landslides
–> Being able to recognise form a picture.
What are the causes of water erosion?
- Fire
- Climate change
- Agricultural management
- Land management
- River management
What does Lane’s balance describe?
It is a balancing act; namely, the river catchment is stable when the aggregating and degrading forces that apply to water and sediment are balanced.
What do the symbols on Lane’s balance mean?
The symbols refer to:
- Qs = sediment load
- D50 = sediment size
- Qw = water discharge
- S = slope
How are causes and effects of water erosion linked in a system?
This can be describe by a system know as “catchment system dynamics”. There are natural and human drivers such as fire/climate change/vegetation and management. The causes are e.g. off-site sediment accumulation, water availability.
