Water Erosion: How do processes involving water change Earth’s surface? Part 1 1.
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Water Erosion: How do processes involving water change Earth’s surface? Part 1 1
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Transcript of Water Erosion: How do processes involving water change Earth’s surface? Part 1 1.
Water Erosion:
How do processes involving water change Earth’s
surface?Part 1
1
What is the MAJOR agent of erosion that has shaped Earth’s land surface?
moving water2
Water moving over land’s surface is called
runoff.
Runoff may cause sheet erosion.
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The amount of water runoff in an area
depends on5 main factors:
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Factors that affect Runoff1. The amount of rain an area receives.
*More rain = more runoff
2. Vegetation - grasses, shrubs & trees reduce runoff.
*More vegetation=less runoff
3. Type of soil - some soils absorb more water than others
4. Shape of the land – steep slopes have more run-off, which causes more erosion
5. How people use the land – parking lots & crop removal increase run-off.
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Runoff overtime:
How does runoff over time affect the
land and water?
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Rills & GulliesAs runoff travels across the soil, rills form.
Rills are tiny grooves in the soil that grow larger forming gullies.
A gully is a large groove or channel in the soil that carries runoff after a storm. It moves soil & rocks.
Gullies only contain water after it rains. 7
Streams & Rivers
Gullies join together to form a larger channel called a stream.
Water continuously flows here and rarely dries up.
Small streams may be called creeks or brooks.
Small streams flow together to form a large stream called a river.
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Rill, Gully, Stream
StreamGully erosion in a pasture. Image by NRCS
Rill erosion at a construction site. Image by M. Mamo, Labels added by UNL
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TributariesStreams grow together by getting water from tributaries.
A tributary is a stream or river that flows into a larger river.
Tributaries collect their water from the drainage basin or watershed.
An example: The Missouri & Ohio rivers are tributaries of the Mississippi river.
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Rivers & Tributaries
http://images.google.com/imgres?imgurl=http://knol.google.com/k/-/-/3ajhc7zrwtav1/c1ssz4/figure-1%2520(2).bmp&imgrefurl=http://knol.google.com/k/new-orleans-the-geologic-difficulties-with-the-big-easy-part-1&usg=___SPqqMAUDGF2VVgD-x0Wwvs-5xk=&h=394&w=432&sz=31&hl=en&start=5&um=1&tbnid=ShJceJzlrtYlWM:&tbnh=115&tbnw=126&prev=/images%3Fq%3DMississippi%2Briver%2Band%2Bits%2Btributaries%26hl%3Den%26um%3D1 11
Rivers: * cause erosion and create valleys, waterfalls, flood plains, meanders and oxbow lakes.
*form on steep mountain slopes.
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How do they flow? Quickly and follow a narrow path
How do they erode? Rapidly
The result is that rivers form deep, V-shaped valleys.
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Valleys
http://www.google.com/imgres?imgurl=http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBytes%2520GCSE%2520Blog%2520Resources/Images/Rivers/V-shapedvalley.jpg&imgrefurl=http://geobytesgcse.blogspot.com/2006/11/upper-course-of-river-v-shaped-valleys.html&usg=__Hp8C8YOunbWzJy9E7kbQcOiURzA=&h=308&w=411&sz=47&hl=en&start=0&zoom=1&tbnid=giwF1FppYFy8zM:&tbnh=116&tbnw=154&ei=-kk2TfKtEMH68AbI__2tBA&prev=/images%3Fq%3Dv-shaped%2Bvalley%26um%3D1%26hl%3Den%26sa%3DN%26biw%3D1280%26bih%3D531%26tbs%3Disch:10%2C35&um=1&itbs=1&iact=hc&vpx=247&vpy=77&dur=701&hovh=194&hovw=259&tx=161&ty=116&oei=g0k2TbG1L4T58Aa8nOC7Aw&esq=12&page=1&ndsp=22&ved=1t:429,r:1,s:0&biw=1280&bih=531
http://images.travelpod.com/users/the-boy_picot/3.1149265860.580x-nice-v-shaped-valley.jpg
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Features of rivers:
What features are formed by erosion
along a river?
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WaterfallsOccur where?
Where a river meets an area of hard & slowly eroding rock
Then flows over softer rock downstream.
How does softer rock erode? The softer rock erodes away
faster.
What results from this erosion? A waterfall develops.
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Waterfalls at the Plitvicka Jezera National Park in Croatia Minnehaha Falls,
Minneapolis Minnesotahttp://images.google.com/imgres?imgurl=http://realestate-inminnesota.com/images/Minneapolis.jpg&imgrefurl=http://realestate-inminnesota.com/&usg=__kBY-WaWcelJlC-sNAEDq6zr8eLY=&h=599&w=800&sz=162&hl=en&start=5&um=1&tbnid=WO5G4jC_rIKDMM:&tbnh=107&tbnw=143&prev=/images%3Fq%3Dminnehaha%2Bfalls,%2Bmn%26ndsp%3D18%26hl%3Den%26sa%3DG%26um%3D1
Waterfalls
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Flood Plain
What is a flood plain?A wide valley in which a river flows
What happens to the land during a flood?The water in the river over flows its banks into this wide river valley area.
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Flood Plain
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MeandersWhat are meanders?Loop-like bends in the course of a
river.
Where & how do they occur?They occur as the outer bank of a river is eroded & deposits are dropped on the inner bank of the bend in a river.
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Example: The southern stretch of the Mississippi River meanders on a wide, gently sloping flood plain area.
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Mississippi River Meanders
http://images.google.com/imgres?imgurl=http://www.ecology.info/img/Mississippi-River.jpg&imgrefurl=http://www.ecology.info/article.aspx%3Fcid%3D12%26id%3D10&usg=__B9CvpJJ70Ydm7HE2LjHs3GW76Ec=&h=450&w=600&sz=57&hl=en&start=8&tbnid=Q3zaqdFNmc7QVM:&tbnh=101&tbnw=135&prev=/images%3Fq%3Dmeanders%26gbv%3D2%26hl%3Den%26sa%3DG 22
Oxbow LakesWhat is an oxbow lake?
A meander that has been cut-off from the river.
They may form when a river floods as high water finds a straighter path downstream . As flood waters fall, sediments dam up the ends of the meander and a lake forms.
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Oxbow Lakes
http://muller.lbl.gov/travel_photos/AmazonWebPages/AmazonWebPages-Images/1.jpg24
