2.2% of all water is freshwater. 1% of freshwater is surface water. 1% of all surface water is rivers.
Amazon: BA=6.144.727km2, L=6.400km, Discharge=219.000 m3/sec (Amazon=20% of all river discharge) GANGES=4%, CONGO=4%
Congo: BA=3.730.474, L=4.700 Discharge=41.800
Nile: BA=3.254.555, L = 6.650, Discharge =5.100 Danube L = 49km, Rhine=1232 Rhine
Mississippi, BA=3.202.230, L = 6.275, Discharge =16.200 Jordan L = 251km Tigris =1900km
Ob BA =2.972.297 L=5.410 Discharge=12.800 Ganges=2510km Colorado=2339km
Parana BA=2.582.672 L=3.998 Discharge=25.700 Okavango = 1600km
Yenisey BA=2.554.482 L=5.539 Discharge=19.600
Lena BA=2.306.772 L=4.400 Discharge=17.100
Niger BA=2.261.763 L=4.167 Discharge=9.570
Mackenzie BA=1.743.058 L=4.241 Discharge=10.300 DISCHARGE: Amazon, Ganges/brah, Yangtze,
Yangtze BA=1.722.155 L=6.300 Discharge=31.900
South America (Big chunk of SA), drains into Atlantic (biggest drainage basin the
world 7million km2) Longest river (maybe the Nile)....length of the Amazon is not
stable, Most of the river is at LOW elevation – starts @ 5000m ends @ 100m.
Countries: Peru, Bolivia,VEnezuala, Colombia, Ecuador,and CBrazil
Basin: 70% of basin in Brazil, Tocantins Basin (part of basin) at mouth is BIG island
(Marajo) (Tocantin Basin goes south of the island) Amazon goes north. Madara is the
MAIN basin and covers 20%
Sediment: River drops from Andes QUICKLY & carries sediment. When it goes to flat
area, some of the sediment drops out, Natural extension zone (where sediment drops
off) , River turns brown because of sediment that is picked up as it runs off from high
in the mountains. Wide rivers ...milky brown colour.
EROSION: LRiver bank erosion adds sediments. Flood plains deposit sediment
elsewhere Medeira brings large amounts of sediment (aka sediment DOUBLES when it
hits the Madeira) Most of the sediment comes from Andes & Madeira.
Black Rivers (E.g. Rio Negro). More North/West DOESNT originate in Andes.
Carries partially decomposed organic matter. More acidic than the water coming from
Andes. As a result, has different species. River level is highest in June/July.
Clear Water Rivers: low sediment and nutrient load. More South-East
Originate in Brazillian shield & Northern Shield. **when rivers meet you can
get big mixing effects (Rio Negro & Amazon). Takes about 10km before waters
fully milk (RioMadeira) river level is LOWEST in junejuly
fluctuations in river levels: greatest fluctuations are in southwestern
Brazillian rivers, especially Madiera, Purus,Jurua
MANAUS: 1 million people living, No bridges ***Unique to Amazon*, Ferries go
across, Ocean vessels can make it to Manaus (3-4 km wide)., Sometimes make it to
Iquitos, Low gradient for ships to be able to make it through
Manaus – RioNegro – by this time has 50% of flow that goes to Ocean. BY ocean –
river is carrying 200,000m of water to ocean PER SECOND
Medara & Negro – carrying LARGE amounts of water (15% & 14%)
Rainfall/FLUCTUATIONS: There is extremely high rainfall, 10000 mm/year in its
highest area. drains into Amazon & then into Atlantic. 25-30% of rainfall makes it to
Atlantic N. Hemi summer = high flows in river (June, July, August). Flood season
is June-August. Drought = Jan-April S. Hemi winter = high flows (Feb, March)
flood season is Jan-May Wet & dry cycle=big variations water / 10-14m/yr ↑ ↓
DAMS: No dam along the Amazon because gradient is too low No dams on tributaries
that come from Andes because there is a lot of sediment travelling with water
would damage the dam
ROADS: Few roads through the Amazon, Roads are NOT paved, Bare soil becomes
road. Ferries go across, Roads transport for trucks carrying wood. , Rain becomes
problematic for roads/trucks
DEFORESTATION: rates have increased substantially. Every year 19km2 is cut from
amazon. Once deforested burn land & use for agriculture once that dies then
they use it for cattle farms.
FIRES: 500 fires/year. Habit destruction when you burn it the re-growth is
different from the original forest.
LOGGING: Logging = bare soil = erosion , Pasture ↑ 50% of water runs over land
causes erosion. in water running over surface of land.↑
Prediction for 2020: Trees shade the river so there is not too much evaporation. If the
river is then exposed (because of logging) then there is HIGH RATES of evaporation of
water Climate Change= less rain in rainforest. Highprobability of area in Brazil will
have 20% reduction. 5-10% reduction in rainfall because of logging...not due to
WHY LOGGING:: Hardwood: for export, Cattle: Large areas have been converted
to pastures for cattle,Cattle imports & exports = large economic market for cattle in
Brazil, Crop: land is burned and turned into agriculture, Settlements:,
Gold: big resource in Brazil/Amazon. 10% of total gold comes from Brazil.
80% of Brazil gold comes from Amazon. Most gold mining happens illegally (clear
forest & dig) ...must go thru a LOT of mud to find a little bit of gold. Gold miners use
mercury (general safe except when you boil it. Vapours combined with carbonate =
inorganic mercury = toxic) they burn the mercury to make gold nuggets. **illness is
Gold Production per year: Global – 400 ton, Brazil – 30-50ton, Brazillian
Amazon : 24-40ton
Release of Hg into atmosphere (through burning, waste, etc): Global – 600-
1000ton, Brazillian Amazon – 100-200ton (est. 2040) (est. 80s/90s=200ton) **release
of Hg into area varies with temperature of the air & dependant on the Sun... NO SUN
= lower uptake of Hg into atmosphere. Mercury eventually rains = POLLUTED RAIN.
Polluted rain falls on forests ...gets absorbed by trees (so not much going to river
system. Polluted rain falls on pastures....50% Hg makes it to river. More sediment in
river = more HG. This has implications for eating fish *injesting mercury*. Transfers
to humans thru breastfeeding as well. Gold mining affects people downstream**
shown in hair mercurcy conc.
Logging goldmining health effects.
Continental shelf around NA-drop into deep part of ocean near outlet of Mississippi.
Missouri River takes water from Canada, drains it south. Mississippip+Misouri+Ohio
River meet in St. Louis. Drains in 31 US states (41% of US contiguous states)
RAINFALL: most rain comes in Ohio basin (Louisiana has highest rainfall) yearly
amount is HALF what you get in Amazon. Ohio river adds significant portion of
discharge (Missouri+ upper Mississippi is small portion of discharge) combine to make
Sediment: carries large amount of sediment. Largesr Sediment drops out first—river
builds its own levy, cuasing river to build a landscape. As you get further down the
river it is no longer carrying gravel & coarse sand. Mississippi deposits in Bird Food
Delta & releases sediment into ocean. Deltas continuously change because the levys
are building up – when the river floods it breaks its own levys & flood into the area
behind and you get an erosion of the channel/entire delta area.
History of colonization:
1542- de Sato was looking for gold. Came from Florida than travelled a little west,
from there he came across the Mississippi. He managed to cross, travelled a little
more west than died. reported that there was no gold, just mosquitoes. nothing
happened for another 140 year
1672- French priest (la sale) in 2canoes went down Mississippi. Roughly when they
got to Arkansas. saw that the natives were wearing European jewellery. Never made
it to the mouth because he wanted to avoid conflict with the Spanish.
1682- Cavelier made all the way to the Delta and Gulf of Mexico.
1687- went back b/c Franceking told him to go back & form trading post. was unable
to find the Mississippi, because the outlet is so small.
1699- he was still interested in discovering the area, so he sent more people there.
1718- founded New Orleans when he portaged for 2km. little path is portaging route
– called BIjoue. . New Orleans is in a bad area, there is a lot of rainfall and hurricanes.
But it was chosen to be built there on the levy. It is a good shelter from the
hurricanes. Was at the mouth of the basin, so that no one could enter the Mississippi
w/out passing New Orleans, likewise if things are coming down the Mississippi they
need to travel through New Orleans.
1803- Jefferson wanted to buy New Orleans from Neopolean for 10 millions dollars.
He didn’t want to sell it.
1850- people believed that New Orleans will be the largest and most important city
because of all of the economic activity.
Invention of the railways- made it possible to transport good throughout the country
without the Mississippi river, and still doing quite well. Not all the activity went to New
Orleans. New York became the most powerful city because of these railways and the
Advancements- drained the water into one canal. Take the water and pump it over
the ridge and drain it into the lake. New Orleans's location on the Mississippi River
delta had restricted the city's growth for 200 years, because most of the surrounding
land was useless swamp. Using modern technology, developers drained marshlands
and built new neighbourhoods. 1950-1970 the greater metropolotian area doubled in
size geographically but everyone left to go to the suburbs.
River Meanders- there has been lots of change in the river throughout time.