RIVER GLOSSARY
What is the starting point of a river called?
Source.
Name the three main river processes.
Erosion, transportation, and deposition.
What is a smaller river that flows into a larger river called?
Tributary.
What is a flood?
A flood occurs when water covers land that is normally dry.
Which is bigger: a river or a stream?
A river.
What is the geographical term for the amount of water flowing past a point in a river per second?
Discharge.
What is the transportation process in which large stones roll along the river bed?
Traction.
What is the name of the boundary separating two drainage basins?
Watershed (drainage divide).
Name two methods used to control river flooding.
Examples include dams, embankments (levees), afforestation, and flood-relief channels.
A river flows from a mountain to the sea. Which place is usually at a higher elevation: the mountain or the sea?
The mountain.
What is the term for water flowing over the land surface into a river?
Surface runoff (overland flow).
Why does a river usually flow faster on the outside bend of a meander?
The water is generally deeper and experiences less relative friction, causing faster flow.
What happens to surface runoff when rainfall intensity exceeds the soil's infiltration capacity?
Surface runoff increases.
How does planting trees help reduce flood risk?
Trees intercept rainfall and can improve infiltration, slowing surface runoff into rivers.
If heavy rain falls for several hours, what is more likely to happen to the river's water level: rise or fall? Why?
Rise, because more water may enter the river through surface runoff and other pathways.
Define wetted perimeter.
The length of the river bed and banks in contact with water in a channel cross-section.
Why does a river deposit sediment when its velocity decreases?
The river loses energy and transporting capacity, so it deposits material it can no longer carry.
Explain how deforestation can increase the risk of flooding.
Fewer trees reduce rainfall interception. Deforestation can also reduce infiltration, causing more rapid surface runoff into rivers.
Give one advantage and one disadvantage of constructing a dam.
Advantage: It can store floodwater and regulate downstream discharge.
Disadvantage: It is expensive and may flood habitats or settlements upstream.
Two rivers have the same cross-sectional area. River A flows at 2 m/s and River B flows at 4 m/s. Which river has a higher discharge?
River B, because its velocity is twice as high and discharge depends on cross-sectional area multiplied by velocity.
Explain the difference between infiltration and throughflow.
Infiltration is water entering the soil from the surface. Throughflow is the sideways movement of water through the soil.
Explain how an oxbow lake is formed.
Erosion narrows the neck of a meander. During high discharge, the river may cut through the neck, creating a straighter channel. Deposition blocks the ends of the abandoned meander, forming an oxbow lake.
A river has a cross-sectional area of 20 m² and an average velocity of 3 m/s. Calculate its discharge.
Discharge = cross-sectional area × average velocity = 20 × 3 = 60 m³/s.
A town experiences frequent flooding but has a limited budget. Recommend two sustainable flood management strategies and explain why they are suitable.
Afforestation can reduce surface runoff, while flood warning systems allow people to prepare and evacuate. Both can reduce flood risk without requiring expensive major engineering structures.
A farmer cuts down trees near a river. After heavy rain, the river floods more quickly than before. Explain the possible connection between these events.
Removing trees reduces interception and can decrease infiltration, so more rainwater reaches the river quickly as surface runoff, increasing flood risk.