Short description about river landforms

1. RIVER LANDFORMS
Xon Vilahur i Godoy
Institut de Llagostera

2. RIVER-BASIN
 A river basin is an area drained by a river
and its tributaries. Other river features
include:
 Watershed, an area of higher land
separating two drainage basins.
 Source, the place where a river begin
 Tributary, a smaller river joining a large
river
 Confluence, the place where two rivers
join.
 Mouth, the place where a river enters in a
lake or the sea
 Streams or brooks are the names given to
small rivers
 Drainage pattern is the way rivers are
arranged on the landscape, the most
commons ar, dendritic, parallel or radial.

3. UPPER COURSE:
WATERFALLS AND RAPIDS
 A waterfall is a place on a river where water flows vertically. Waterfalls are
a common feature in the upper course of many large rivers. A waterfall
occurs when a layer of hard resistant rock lies over a layer of softer rock,
which will erode more easily.
Rapids are a series of little waterfalls; these can be found where a waterfall
has retreated, the hard rock layer is undercut causing the waterfall to move
upstream. They are found where there are alternative bands of hard and
soft rocks.

4. MIDDLE COURSE:
FLOODPLAIN, MEANDERS AND OX-BOW LAKES
 Less steep gradient, lateral erosion,
the river starts to meander.
 Over time, the loop of a meander
becomes tighter: the river cut
across the neck of the meander to
form a straight river channel and
forms an ox-bow lake.
o Floodplains: area of flat land
formed on either side of a river,
combination of erosion and
deposition :
 Deposits of alluvium ( "http://www.libraryindex.com/pages/8308/meander.html">meander</a>
 Fertile and good for farming and
agriculture.
 Floodplains are highly populated.
http://www.youtube.com/watch?v=8uV-
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5. FLUVIAL TERRACES
 Fluvial terraces : elongate deposits of sediments
parallels to the sides of floodplains and fluvial valleys.
 Remnants of earlier floodplains that existed at a time
when a river was flowing at a higher elevation; then the
stream has changed its elevation and has created a new
floodplain.
 Due to changes in the base level or in the volume of the
fluvial flow (changes in climate: glaciations)

6. MOUTHS: DELTAS AND ESTUARIES
 River channel deep and wide,
large discharge
 Valley, wide and flat, wide flood
plain.
 Deltas , deposits of alluvium,
sand, silt and clay at the mouth
of large rivers (Ganges, Nile,
Ebre,…) in tideless seas.
 The deposit of the river load
occurs faster than the sea can
remove the material.
ADJECTIVES:
 Permanent land feature, rich in  Large/ narrow
alluvium, fertile farmland.  long/short
 small/big
 deep/shallow
 wide/narrow
 fertile/sterile
 good/bad

7. MOUTHS: DELTAS AND
ESTUARIES
 Estuaries: funnel-shaped
mouths.
 Mouth of a wide river when
its current is met by the
tides.
 Most are found where an
existing river has had its
lower reaches flooded ed
river after changes in sea
level.
 In Galicia are called Rías,
and in Norway are called
Fjords

8. FLOODINGS
 Flood : river that overflows its banks
 Causes: A rapid increase in discharge over a short period of time,
so the river system is unable to transport it away.
 Factors: Both human and physical factors
 Physical factors: prolonged rain or a short heavy rain storm, snow
melt which releases stored water; steep slopes, narrow valleys or
impermeable rocks.
 Human factors: Deforestation, construction of urban areas,
changes of the natural course of the river.

9. FLOODINGS
 Impacts: devastation, extensive
damage, destruction of food supplies,
buildings, farmlands, vehicles,
transports, power and people.
 Worse impact on LEDCs than on
MEDCs. (emergency services,
money, equipments, and poor
communications in LEDCs make
recovery more difficult.)
 Benefits, deposits fine silt and
sediment, which helps to fertilise the
soil and generates excellent conditions
for farming.
Some LEDCs use river flooding to
cover farmland with fertile alluvium and
also to provide water for irrigation
channels (e.g. Ganges in Bangladesh)
 Prevention: prediction, prevention
and control.
Flood management to reduce the
impact of flooding: river management,
changing land use, dams and
reservoirs...