Rivers General Flashcards

What is a river drainage basin?

An area of land drained by a river and its tributaries

What is a source?

The starting point of a river.

What is a tributary?

A smaller river that joins the main river.

What is a confluence?

The point where two rivers join / connect

What is a floodplain?

The flat land either side of a river where it usually floods.

What is an estuary?

The tidal area where the fresh water meets the sea.

What is the mouth?

The point where the river flows into the sea.

What is the watershed?

The imaginary line that separates drainage basins .

What is a long profile?

How the river changes from the source to the mouth.

What is a cross profile?

How the river changes shape across the river valley.

What is the gradient like in the upper course?

Steep.

What is the gradient like in the middle course?

A gentle slope.

What is the gradient like in the lower course?

Shallow and flat.

What is the cross profile of the upper course?

A v-shaped valley

What is the cross profile of the middle course?

A gentle sloped valley

What is the cross profile of the lower course?

A flat valley.

How does the velocity change from the upper course to the lower course?

The upper course is the slowest and it gets quicker as it goes down.

What are the landforms in the upper course?

Waterfalls, gorges and interlocking spurs.

What are the landforms in the middle course?

Meanders and oxbow lakes.

What are the landforms in the lower course?

Flood plains, levees and estuaries.

How does the river channel’s shape change going down the river?

In the upper course it is narrow and shallow but as you go down the river it gets deeper and wider.

How does the shape of the sediment change going down the river?

The sediment starts as boulders and turns into rounder pebbles before becoming sand and silt.

What is lateral erosion?

The widening of the river channel

What is vertical erosion?

The deepening of the river channel

What is a meander?

A bend in the river channel.

What are levees?

Natural embankments

How does prolonged rainfall affect the processes in the water cycle?

The saturated soil causes less infiltration so there is more surface run off which leads to a shorter lag time.

How does heavy rainfall affect the processes in the water cycle?

The infiltration rate is too slow to cope so there is more surface run off which leads to a shorter lag time.

How does geology affect the processes in the water cycle?

Impermeable rock/soil leads to less infiltration so there is more surface run off which leads to a shorter lag time.

How does the relief of the land affect the processes in the water cycle? (steep slopes)

Steep slopes leads to less infiltration so there is more surface run off which leads to a shorter lag time.

How does the relief of the land affect the processes in the water cycle? (low lying land)

Low lying land leads to saturated soil so there is more surface run off which leads to a shorter lag time.

How does urbanisation affect the processes in the water cycle?

Impermeable material leads to less infiltration so there is more surface run off which leads to a shorter lag time.

How does deforestation affect the processes in the water cycle?

No tree roots means no interception so there is less infiltration so there is more surface run off which leads to a shorter lag time.

What is a hydrograph?

A graph that shows how a river responds to a period of precipitation / rain

State the formula for Cumecs.

Velocity of river x volume

What is peak rainfall?

The highest amount of raifnall.

What is a lag time?

The difference in time between peak rainfall and peak discharge

What is discharge?

The amount of water passing a given point along the river.

What is the rising limb?

The rising limb shows how quickly the discharge rises.

List 4 soft engineering strategies

River restoration , planting trees, flood plain zoning , flood warnings.

What does river restoration do?

Return the river to its natural course.

What are the advantages of river restoration?

It’s sustainable, meandering creates ecosystems and it protects high value land.

What are the disadvantages of river restoration?

It can flood upstream urban areas.

What are the advantages of planting trees for river restoration?

It decreases flood risks, increases habitats and the root stabilise the soil so there’s less erosion.

What are the disadvantages of planting trees for river restoration?

It’s best in the upper course and in urban areas tree litter can block drains and rivers.

What is flood plain zoning?

Building high value land away from a river.

What are the advantages of flood plain zoning?

Reduces flood risk of high value land and decreases the cost of flood damages.

What are the disadvantages of flood plain zoning?

Large demand for new housing and homes are already built on floodplains.

What are flood warnings?

The news reporting weather events so people can act accordingly.

What are the advantages of flood warnings?

People have time to react (prevent flooding/evacuate/relocate valuables) and people stay safe.

What are the disadvantages of flood warnings?

People don’t listen to advice and some weather reports are inaccurate.

What is a dam?

Dams are large concrete walls that block the flow of water and choose when to allow water through.

What are the advantages of a dam?

It boosts tourism, provides hydroelectric power and promotes new habitats.

What are the disadvantages of dams?

It forces people to move (destroys and displaces livelihoods), there’s less nutrients for farms and it’s expensive.

What is channel straightening?

Cutting through meanders to create a fast straight channel to move water out of high value land.

What are the advantages of channel straightening?

It improves trade, reduces flood risk and increases home-owner confidence.

What are the disadvantages of channel straightening?

The changing ecosystem destroys habitats, it’s unattractive , increase pollution and floods downstream.

What are the advantages of embankments?

They prevent flooding, create habitats and walking routes and it is cheap.

What are the disadvantages of embankments?

They decrease river access for boating / fishing , are unreliable and has high maintenance costs (for dredging etc.)

What is a flood relief channel?

A channel that water is diverted through to decrease the amount of water held in the original channel.

What are the advantages of a flood relief channel?

There is calm water for boating, it’s more secure and artificial reed beds and grass creates new habitats.

What are the disadvantages for a flood relief channel?

It takes a long time to build, it’s expensive and it floods downstream forcing people to displace.