river systems
DESCRIPTION
River Systems. Earth Space Science Mr. Coyle. The Hydrologic Cycle. Infiltration = Groundwater System. Runoff = Surface Water System Runoff = Precipitation - Evapotranspiration. Where is the Water ?. RIVERS & STREAMS. Water Reservoirs The Hydrologic Cycle Surface Water Systems - PowerPoint PPT PresentationTRANSCRIPT
River Systems
Earth Space Science
Mr. Coyle
The Hydrologic Cycle
• Infiltration = Groundwater System• Runoff = Surface Water System
• Runoff = Precipitation - Evapotranspiration
Where is the Water ?
RIVERS & STREAMS• Water Reservoirs
• The Hydrologic Cycle
• Surface Water Systems
• Meandering
• Deltas/Alluvial Fans
• Floods and flooding
• Rivers:– Provide water and nutrients for agriculture
– Provide habitat to diverse flora and fauna
– Provide routes for commerce
– Provide recreation
– Provide electricity
www.aquatic.uoguelph.ca/rivers/chintro.htm
Importance of rivers
• Discharge- volume of water
• Velocity- rate of water movement
• Gradient- slope of inclined surface
Natural Watercourses
• The shape, size and content of a river are constantly changing, forming a close and mutual interdependence between the river and the land it traverses.
Variation in time and space
What is a Watershed?
www.aquatic.uoguelph.ca/rivers/chwater.htm
www.dec.state.ny.us/website/2000/watersheds.gif
www.epa.gov/watertrain/ecology/ecology21.html
The Worlds Largest Rivers
Largest Rivers of the World
River Outflow mi. kmNile Mediterranean Sea 4,180 6,690
Amazon Atlantic Ocean 3,912 6,296
Mississippi-Missouri Gulf of Mexico 3,710 5,970
Yangtze Kiang China Sea 3,602 5,797
Ob Gulf of Ob 3,459 5,567
Huang Ho (Yellow) Gulf of Chihli 2,900 4,667
Yenisei Arctic Ocean 2,800 4,506
Paraná Río de la Plata 2,795 4,498
Irtish Ob River 2,758 4,438
Zaire (Congo) Atlantic Ocean 2,716 4,371
Heilong (Amur) Tatar Strait 2,704 4,352
Lena Arctic Ocean 2,652 4,268
Mackenzie Beaufort Sea (Arctic Ocean) 2,635 4,241
Niger Gulf of Guinea 2,600 4,184
Mekong South China Sea 2,500 4,023
Mississippi Gulf of Mexico 2,348 3,779
Missouri Mississippi River 2,315 3,726
Volga Caspian Sea 2,291 3,687
Madeira Amazon River 2,012 3,238
Purus Amazon River 1,993 3,207
São Francisco Atlantic Ocean 1,987 3,198
Yukon Bering Sea 1,979 3,185
St. Lawrence Gulf of St. Lawrence 1,900 3,058
Rio Grande Gulf of Mexico 1,885 3,034
Brahmaputra Ganges River 1,800 2,897
Indus Arabian Sea 1,800 2,897
Danube Black Sea 1,766 2,842
Euphrates Shatt-al-Arab 1,739 2,799
Darling Murray River 1,702 2,739
Zambezi Mozambique Channel 1,700 2,736
Tocantins Pará River 1,677 2,699
Approx. length
Discharge
River m 3̂/sec mm/yr % of total entering oceans
Runoff Ratio
1 Amazon, Brazil 190,000 835 13.0 0.472 Congo, Zaire 42,000 340 2.9 0.253 Yangtse Kiang, China 35,000 560 2.4 0.504 Orinoco, Venezuela 29,000 845 2.0 0.465 Brahmaputra, Bangladesh 20,000 1070 1.4 0.656 La Plata, Brazil 19,500 235 1.3 0.207 Yenissei, Russia 17,800 215 1.2 0.428 Mississippi, USA 17,700 175 1.2 0.219 Lena, Russia 16,300 210 1.1 0.4610 Mekong, Vietnam 15,900 630 1.1 0.4311 Ganges, India 15,500 455 1.1 0.4212 Irrawaddy, Burma 14,000 1020 1.0 0.6013 Ob, Russia 12,500 135 0.9 0.2414 Sikiang, China 11,500 840 0.8 -15 Amur, Russia 11,000 190 0.8 0.3216 St. Lawrence, Canada 10,400 310 0.7 0.33
U.S. Precipitation Map
U.S. Runoff Map
Notice the effect of the Rocky Mountains
Laminar vs. Turbulent Flow
Turbulent flow in the headwaters of a rushing mountain stream
Near-Laminar flow in the center of a river channel
So Where Does The Stream Move Fastest?
• Headwaters move slowest• Mouth of stream moves
fastest • Laminar flow is more
efficient than turbulent flow.
• Deeper stream move faster than shallow streams
Sediment Load
Movement of Bedload by Saltation
Sedimentation
Longitudinal Stream ProfileCan be divided into 3 main parts
Drainage (Tributary) System
Transport System Distributary System
Drainage System
• Stream energy is spent eroding downward into the basement rock and...
• Moving sediment
• Creates “V” shaped canyon and valleys
• When streams emerge from the mountain front, they often deposit some of this sediment forming alluvial fans.
Alluvial FansTransition from Tributary to Transport
Aging Rivers: How Old Is It?
• Young- rapid bed erosion, waterfalls, rapids, v-shaped valleys, few tributaries, low volume
• Mature- well established tributaries, larger volume of water, erode banks and not the bed (bottom), meanders, oxbow lakes
Flash Flooding & Sheetwash
Braided Pattern = high slope + high stream power + coarse bed materials
Braided Streams & Rivers
• High sediment load
• Constantly changing course
• Floodplain is completely occupied by channels
• Many small islands called mid-channel bars
• Usually coarse sand and gravel deposits.
Meandering Rivers
Meandering Rivers
• Constantly erode material - Cut bank
• Constantly deposit material - Point bar
• Change their channel course gradually
• Create floodplains wider than the channel– Very Fertile soil– Subjected to seasonal flooding
Formation of Meanders
Point bar deposits
Point Bar Deposits
Point bar deposits grows laterally through time
Cut bank erosion
Point bar deposits }Meander
loop
Formation of an Oxbow
Meandering streamflowing fromtop of screento bottom
Maximum erosion
Maximum deposition
Oxbow Lake
Oxbow cuttoff
Meander scars
1993 Mississippi Flood
Flooding & Sedimentation
Deltas - Distribution Systems
If the Mississippi
changes course again, what
will happen to the City of
New Orleans?
Things to Remember
• Rivers are part of a larger hydrologic system
• The have three main components:
• Drainage (Tributary) systems - collect water
• Transport Systems - move water along– Alluvial fans, braided streams, meandering streams
• Rivers exceed their capacity during floods
• Distributary systems - return water to the sea– Deltas.