Rivers form from rainwater flowing over land and collecting in streams. They flow from high elevations down to oceans, lakes or other bodies of water. Rivers have common structures like watersheds, basins, tributaries and channels. The largest rivers include the Nile, Amazon and Mississippi. Rivers experience flooding when water exceeds capacity. Dams help control flooding but are also used for water collection and power generation. Bridges allow crossing rivers. Life like bears and beavers inhabit rivers, which support surrounding plant growth. Flow rates are measured in cubic meters per second.

2. The meaning of a river.
 A river is a natural stream of freshwater flowing towards
an ocean, a lake, a sea, or another river. In a few cases, a
river simply flows into the ground or dries up completely
before reaching another source of water. Small rivers may
also be called by several other names, including stream,
creek, brook, rivulet, tributary and rill. There are no official
definitions for generic terms, such as river, as applied to
geographic features, although in some countries or
communities a stream may be defined by its size. Many
names for small rivers are specific to geographic location;
one example is "burn" in Scotland and northeast England.
Sometimes a river is said to be larger than a creek, but this
is not always the case, because of the difference in the
language.

3. How do Rivers form?
 Rivers form from rain water which falls on mountain
surfaces and slides off into a path where that water is
collected and a stream of water forms.
 Another way how rivers form is when water falls on
rocks it passes through them or gets collected for a
certain ammount of time. Afterwards it passes to lower
ground and once again forms a river.

4. River Basins
Rivers have structures which are common to all rivers
these are –
Watershed (Area which forms the edge river basin)
River Basin (Area of land drained by a river flowing
into a main river)
Source (It is from where the river begins)
Tributary(A small stream flowing into the river)
Channel(It is where a river flows)
Mouth(This is where a river flows into a lake or
the sea)

5. The biggest!
The biggest and the most popular rivers in the world are
the -
Nile, Zaire, Zambezi in Africa
Ganges, Volga, Yangtze in Asia
Murray-Darling in Australia
Danube, Rhine in Europe
St.Laurence, Mississipi, Colorado in North America
and the Amazon in South America.
As you might notice rivers a re distributed on all
continents except Antartica because its an exception for
being filled with ice. The longest river in the world is the
Nile of a length of 6,690km whilst being the largest is the
Amazon river having a river basin of 6,915,000 km²

6. Flooding
 Floods occur when the water capacity in the river is
exceeded.
 Floods cause huge troubles in forests and in villages
near those rivers and some can be catastrophical. A
couple of cases are when the river overflows with so
much water that houses can be swept away with the
water, or the area will be overflooded for weeks or
months!
 The Causes of flooding are Melting of snow, Failure
of non-made dams, Deforestation, Urbanisation,
Excessive precipitation.

7. Preventing, Helping and supporting
 Large rivers are in a need of control so most of them
were provided with Dams.
 Dams are large barriers which control river flow and
prevent floods.
 But they are not used for that reaon only! People use
dams to collect water and use it for their everyday
needs. They are also used for getting electricity from
use of turbines. The turbines are turned and the
movement produces electric energy which is stored in
generators and then spread to cities, towns, etc...
 Also By taking silt out of the river’s bed and placing it
on the banks makes the river deeper

8. Waterfalls.
 There are many types of rivers which have different types
of structures.
 Most rivers start forming in the mountains and continue
slowly to descend to sea level while some descend to only
a few meters and then end up becoming a waterfall.
 A waterfall is when the water in a river reaches a cliff and
falls rapidly downwards.
 These waterfalls are both fascinating and dangerous.
They are fascinating because they usually form a
beautiful rainbow right next to it and the water falling
shines at the drop. But they are mostly dangerous for the
main reason that people riding canoes or swimming in
that river can go to the edge and fall off of the waterfall!

9. Subterranean Rivers
Most but not all rivers flow on the surface.
Subterranean rivers flow underground in caves or
caverns. Such rivers are frequently found in regions
with limestone geologic formations. Subglacial
streams are the braided rivers that flow at the beds of
glaciers and ice sheets, permitting meltwater to be
discharged at the front of the glacier. Because of the
gradient in pressure due to the overlying weight of
the glacier, such streams can even flow uphill. These
rivers can also be found not very far from geisers or
areas where lots of rain water is stored in the stone.

10. Bridges
 One of the simplest ways to cross a river from one side
to the other is by using a bridge. Bridges are used for
getting people over rivers much easier t and faster
mobilation than boats if crossing with a vehicle.
 The most recent bridges over rivers are made to
withstand serious floods, some other bridges are
extended with towers which carry transmission
antennas and some even have restourants on them like
the Novy Most in Bratislava.

11. Frozen Rivers
 You can usually find frozen rivers in cold places in the
north. Rivers only freeze when water movement
reduces and water flow slows down.
 You can mostly find frozen rivers behind dams for the
main reason that water movement is slow there.
 Even though these rivers look like they’re completely
frozen they actually aren’t.Only they’re surface freezes
and the rest is water,sometimes the surface doesn’t
freeze completely either.

12. Life on Rivers
 Rivers are full of life and nature!
 In countries like America and Russia you usually find
bears which stay in groups next to the rivers or in
caverns by themselves. Bears mostly stay there for food
(fish, deers, etc...) and water.
 You can even find beavers which make lodges and
dams out of wood. They live in families in one area of
the river or move about.
 The water in the rivers also provides its water to plants
growing around it creating small forests around it with
trees taller than the ones further off the river bank.

13. Untamed river flow
 Rivers which have secondary channels flowing into it
or out of it have a very rapid movement. That makes it
a wild river which throws a lot of it water on its banks
or even drowns them.
 The population of animals and people next to these
river is usually very low because of the dangerous flows
of these rivers.
 Even building dams there is a dangerous job, so the
rivers are left like they are or secondary rivers are
partially closed for safer flow.
 The only people who go there are extremists which use
these rivers for canoeing and other extreme sports.

14. Flow rate
Volumetric flow rate, also called discharge, volume flow rate,
and rate of water flow, is the volume of water which passes
through a given cross-section of the river channel per unit time.
It is typically measured in cubic meters per second (cumec) or
cubic feet per second (cfs), where 1 m3/s = 35.51 ft3/s; it is
sometimes also measured in litres or gallons per second.
Volumetric flow rate can be thought of as the mean velocity of
the flow through a given cross-section, times that cross-sectional
area. Mean velocity can be approximated through the use of the
Law of the Wall. In general, velocity increases with the depth (or
hydraulic radius) and slope of the river channel, while the cross-
sectional area scales with the depth and the width: the double-
counting of depth shows the importance of this variable in
determining the discharge through the channel.

15. Chemistry of rivers
 The chemistry of rivers is complex and depends on
inputs from the atmosphere, the geology through
which it travels and the inputs from man's activities.
The chemistry of the water has a large impact on the
ecology of that water for both plants and animals and
it also affects the uses that may be made of the river
water. Understanding and characterising river water
chemistry requires a well designed and managed
sampling and analysis.