Eroded sediments have profoundly influenced the development of civilizations around the world.
- Agricultural developmentis often reliant on the nutrient-rich soils created by the accumulation of eroded earth.
- When the velocity of wind or water slows, eroded sediment is deposites in a new location.
- The sediment builds up in a process called sedimentation and creates fertile land.
- River deltas are made almost entirely of sediment that has erodes from the banks and bed of a river.
- The rich delta soils of the Gangetic rivers in India , for example, have created one of the most agriculturally productive areas in the world.
- Loess is an agriculturally rich sediment made almost entirely of wind-blown, eroded sediment.
- The Yellow River in central China gets its name from the yellow loess blew into and suspends in its water.
- The fertile lands around the Yellow River have been among China’s most productive for thousands of years.
Downstream effects of soil erosion include:
- siltation of watercourses and water storages
- reduction in water quality of creeks, rivers and coastal areas.
- Where there is a reduction in the slope of the land, eroded soil, which may contain nutrients, fertilizers, herbicides, or pesticides, can deposit.
- This can be in sediment traps, along contour banks, or in grassed waterways, dams or wetlands.
- The first particles to be deposites are the heavier soil particles, while the finer colloidal clay particles may remain in suspension. Soil remove by gully erosion (especially finer colloidal clay) may be transported directly to creeks or rivers.
Reef water quality
- The Great Barrier Reef is the largest coral reef in the world.
- The quality of water flowing from the land into the reef lagoon has deteriorated over the past 150 years.
- Major floods deliver large levels of pollutants (including eroded soil) from river catchments onto the reef.
Almost 45% of Queensland has soils with some sodic properties. These soils are especially vulnerable to most forms of soil erosion and can affect infrastructure projects such as:
- dams and embankments—if dispersible soils are not compact properly during construction, air voids occur. Water can easily get into these void spaces and cause dispersion of the surrounding soil. Small ‘pipes’ can form which quickly develop into tunnels. Filling a new dam for the first time causes piping and bank failure within a few hours.
- road and tracks—bitumen and concrete readily produce runoff. To build roads, the land has to be disturbed, so erosion and siltation can occur if special stabilising techniques are not uses.
- urban developments—If the land is unsuitable for construction and developments run through existing drainage lines, it can cause severe soil erosion.
- mining and exploration activities—interfere with the natural drainage of the landscape which can cause erosion and siltation of waterways. The development of hundreds of kilometers of tracks and roads for mining exploration clears vegetation, leaving the soil more vulnerable to erosion.
Impact Of Erosion On Human Settlements,Impact Of Erosion On Human Settlements
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