This document provides information about river systems and processes. It discusses the key parts of a river including the upper, middle and lower courses. It describes the landforms associated with each course such as waterfalls in the upper course and meanders and floodplains in the lower course. The document also explains the main river processes of erosion, transportation and deposition and the factors that influence a river's speed and volume.
9. Channelisation Key terms:
1. Uses
Re‐alignment Transpiration Evaporation
2. E.gs
Re‐sectioning Condensation Precipitation Drainage Basin
3. Ltms
Bank Protection E.g. Dyes Infiltration Surface Runoff Watershed
Vegetation Planting
Ways to Hydrologic Parts of a River
manage Cycle ‐River Source
Upper rivers
‐Tributaries
Waterfall, Gorge
Valley River ‐River Mouth
Formation of
Middle River features
Rivers System ‐Distributaries
Meanders Courses of a River
Lower River ‐Upper
Meanders, River Energy ‐Middle
Floodplains, Deltas Processes Volume of Flow ‐Lower
‐Duration of Speed of Flow
Erosion Transportation Deposition Rainfall
‐ Gradient
‐Amount of
‐ Roughness of
Hydraulic Traction Loses energy Rainfall
river bed and
action deposit
Saltation ‐ Size of drainage bank
load (heavier
Attrition basin
Suspension first, then ‐ Depth of river
Abrasion lighter load) ‐Type of soil
Solution ‐ Wetted
Solution ‐ vegetation cover perimeter
11. 1.1 Parts of a River
Upper Course Middle Course Lower Course
Keywords:
River Source River Mouth Tributaries Distributaries Watershed Drainage Basin
12. 1.1 Shape of River Channel
Upper Course Middle Course Lower Course
Steep Gradient
Narrow channel Gradient less steep Very gentle gradient
Shallow Wider channel Widest channel
22. 1.4 River Processes
(Transportation)
• Transportation (Traction)
Larger‐sized materials such as boulders, pebbles & gravel
roll and slide along the river bed as they are too heavy
to be lifted by river water.
26. 1.4 River Processes (Deposition)
• Deposition
– When a river does not have enough energy to either
erode or transport its load put down/ deposit its
load.
– Factors causing Deposition:
1. Period with low precipitation Reduced River Volume
2. A river enters a lake or sea Reduced River Speed
3. A river flows along shallower side of river channel
increased friction reduced River Speed
4. Sudden increase in load due to landslide, etc.
5. River channel is obstructed by aquatic plants or
protruding bed rocks Reduced River Speed
27. 1.5 River Energy
e rg y
r En
R ive
Volume (m3)
As a river’s speed increases, its energy increases.
As a river’s volume increases, its energy increases too.
29. 1.5 River Processes
Factors affecting River Speed
1. Gradient of Channel
St
ee
p
Gr Gen
ad tle
ie Gra
nt die
n t
• Steep river gradient Greater gravitational pull
Increased speed
• Gentle river gradient Lesser gravitational pull
Decreased speed
30. 1.5 River Processes
Factors affecting River Speed
2. Roughness of Channel
Rocks, boulders,
vegetation
Rough Channel Gentle Channel
• Rough river channel more obstacles More
friction Decreased speed
• Gentle river channel less obstacles Less friction
Increased speed
31. 1.5 River Processes
Factors affecting River Speed
3. Wetted Perimeter: Part of river channel that
is in contact with river water
Small wetted perimeter Large wetted perimeter
• Large wetted perimeter More channel area in contact
with water More friction Decreased speed
• Small wetted perimeter Less channel area in contact
with water Less friction Increased speed
32. 1.5 River Processes
Factors affecting River Volume
1. Size of drainage basin
Large Small
• Large drainage area More surface area to collect
rainwater Increased volume
• Small drainage area Less surface area to collect
rainwater Decreased volume
33. 1.5 River Processes
Factors affecting River Volume
2. Presence of Vegetation
Dense vegetation Sparse vegetation
• Dense vegetation increases interception of rain less
surface runoff & more infiltration Smaller volume
• Sparse vegetation decreases interception of rain
more surface runoff Larger volume
34. 1.5 River Processes
Factors affecting River Volume
3. Permeability of rocks
Permeable rocks Less permeable rocks
• Area of permeable rocks higher infiltration less
surface runoff Lower volume
• Area of less permeable rocks lower infiltration
more surface runoff Higher volume
35. 1.5 River Processes
Factors affecting River Volume
4. Climate
– Area with distinct wet and dry seasons
• River volume fluctuates
– Dry areas
• Low river volume throughout the year
– Hot and wet equatorial areas
• High river volume throughout the year
36. Stages of
stream
development:
a youthful
stream, mature
stream, and old
age stream .
37. The Life of A River
Every river has its way,
From Upper, Middle, and all the way,
To the Lower courses of its end,
It Erodes, Transports, then Deposits,
Forming beautiful river landforms,
Waterfalls, Valleys and Gorges,
Meanders, Floodplains, along the way,
Finally, ending its journey in a delta
way.