Geography - River Environments

River Environments

Drainage basin

The area of land drained by a river and its tributaries. Also known as a catchment area.

Watershed

The boundary separating 2 drainage basins

Source

The start of a river

Tributary

A small river channel that flows into a bigger one

Confluence

Where 2 river channels meet

Main Channel

where the largest volume of water flows

Mouth

Where the river meets the sea

Meander

A bend in a river

What is the wetted perimeter?

The length of the river bed and bank

what is the flow of a river?

the direction of water flow

Define the hydrological cycle

The continuous circulation of water within the earths hydrosphere, driven by solar radiation.

Including the movement and storage of water through the atmosphere, land, surface water and groundwater.

Define an input

Water that is entering the river system

Is precipitation an input, process, storage or output?

input

define precipitation

any source of moisture reaching the ground e.g. rain, snow, hail

define processes

water that is moving through the cycle

is surface run-off an input, process, storage or output?

process

define infiltration

water moving through the soil layer

is infiltration an input, process, storage or output?

process

define surface run-off

water flowing over the top of the ground e.g. rivers and streams

is percolation an input, process, storage or output?

process

define percolation

water slowly moving through rock

is throughflow an input, process, storage or output?

process

define throughflow

water flowing through the soil layer parallel to the surface

is groundwater flow an input, process, storage or output?

process

define groundwater flow

water flowing through the rock layer parallel to the surface

define storage

water that is held within the system

is interception an input, process, storage or output?

storage

define interception

water prevented from reaching the ground by trees and grass

is surface storage an input, process, storage or output?

storage

define surface storage

water held on the grounds surface e.g. puddles, lakes, resevoirs

is soil moisture an input, process, storage or output?

storage

define soil moisture

water held in the soil layer

is groundwater storage an input, process, storage or output?

storage

define groundwater storage

water stored in rock

define output

water that leaves the drainage basin

is evaporation an input, process, storage or output?

output

define evaporation

water lost from the ground/plants by the suns energy

is transpiration an input, process, storage or output?

output

define transpiration

water lost through pores in vegetation

Define erosion

the process of rocks being worn away by water in a river

erosion can be vertical or ______

lateral

in the upper course is there more vertical or lateral erosion?

vertical erosion

what does increased vertical erosion in the upper course lead to?

(2 points)

1.v-shaped valleys

2. interlocking spurs

what does increased lateral erosion in the lower course lead to?

(2 points)

1. meanders

2. wide floodplains

name the four types of erosion

1. hydraulic action

2. abrasion

3. attrition

4. solution

define hydraulic action

force of the water enters cracks, pressure increases, the crack expands and breaks off rock

define abrasion

eroded particles picked up by the river scrape and rub against the channel, wearing it away

define attrition

eroded rocks picked up by the river smash into each other and break into smaller fragments. Edges round off as they rub together

define solution

river water dissolves some types of rocks e.g. chalk and limestone

define transportation

the movement of sediment along the long profile of a river

list the 4 types of transportation

1. traction

2. saltation

3. suspension

4. solution

define traction

large rocks and pebbles rolled along the river bed

define saltation

small pebbles and stones bounced along the river bed

define suspension

fine, light material carried along by the river

define solution

minerals are dissolved in the water. This is chemical change.

As rivers move along their course they loose ______

energy

as particles move ______ they become smoother and more ______

downstream, rounded

the heaviest material being carried is ________ first

deposited

define deposition

the dropping of sediment onto the banks or bed of a river when a river slows down and loses its energy

4 reasons why rivers slow down and deposit material

1. volume of water in the river falls

2. amount of eroded material in the water increases

3. the water is shallower e.g. on the inside of a bend

4. the river reaches its mouth and flocculation occurs

more energy=fastest low makes for what kind of meander formation technique

outside of bend + erosion

low energy=slowest flow makes for what kind of meander formation technique

inside of bend + deposition

how is a slip-off slope formed

deposition on the inside of the bend leads to a build up of sediment

how is a steep sided river cliff formed

erosion on the outside of the bend

what does a hydrograph show

a hydrograph shows the link between rainfall and the discharge of a river over a period of time

define discharge

the volume of water that flows in a river per second. Measured in cumecs (cubic metres per second)

define rainfall

the volume of precipitation that has fallen onto the ground in that hour

define time in relation to a hydrograph

how long the rain and increased discharge last. Usually recorded in hours