Water Erosion Chapter 9 Section 2. Runoff and Erosion Moving water is the major agent of the erosion...
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Transcript of Water Erosion Chapter 9 Section 2. Runoff and Erosion Moving water is the major agent of the erosion...
Water Erosion
Chapter 9
Section 2
Runoff and Erosion
• Moving water is the major agent of the erosion that has shaped Earth’s land
Runoff
Groundwater
Runoff
Condensation
Precipitation
Power source
Water Cycle
Evaporation
Runoff and Erosion
• Runoff is water that moves over Earth’s surface
• Five factors that influence amount of runoff– Amount of rain– Vegetation– Type of soil– Shape of the land– How people use the land
• Generally, more runoff means more erosion
Runoff and Erosion
• As water runoff travels it forms grooves in the soil
rills – tiny groovesgullies – formed after a rain as
rills flow togetherstreams – formed as gullies flow
together. They rarely dry up
Runoff and Erosion
River – a large stream
Tributary – a stream or river that feeds
into a larger stream or river
Runoff and Erosion
• Drainage basins or
watersheds are areas from where rivers and tributaries collect their water
Erosion by Rivers
• V-shaped valleys – caused by fast flowing rivers that carve steep slopes along the sides
Erosion by Rivers
• Waterfalls – where water flows over hard rock that erodes slowly, then flows over softer rock that erodes quickly
Erosion by Rivers
• Rapids – areas of rough water where a river tumbles over hard rock.
Erosion by Rivers
• Flood Plain – where a river slows down, spreads out and erodes the land forming a wide river valley
Characteristics
-Steep sides-Mountainous or hilly regions-Rapidly flowing water-White water rapids and water falls
-Curving stream-Gradual slope-Erodes sides-Less swiftly moving-Meanders-Flood plains
-Very slow -Broad flat flood plain-Oxbow lakes
Erosion by Rivers
• Meanders – bends in the river as it erodes softer rock on its bank
• Oxbow Lakes – a meander that has been cut off from the main river
Deposits by Rivers
• Alluvial fans – when a river comes off a mountain and widens, it slows down and deposits sediment as new soil
Deposits by Rivers
• Deltas – When a river flows into a body of water, slows down and drops its sediment.
Groundwater Erosion
• Groundwater – water that soaks into the ground. It fills in the spaces and cracks of soil and rock.
- can cause erosion through chemical weathering
Groundwater Erosion
• Caves – water that mixes with CO2 forms a weak acid that can break down buried limestone and produce hollows
• Sinkholes –
caused when
caves fall in
Groundwater Erosion
• Carbonic acid and calcite can be deposited on cave roofs and floors to form stalactites, stalagmites, and columns.
stalactite
stalagmite
column
Groundwater Erosion
• Karst Topography – an area where there are a lot of sinkholes due to the underground erosion of limestone.