Geography Rivers

Front 1

Drainage basin

Back 1

An area of land that is drained by a river and its tributaries

Front 2

How does a drainage basin operate as an open system

Back 2

Drainage basin operates as an open system as it is connected to other systems and is able to transfer energy and matter through inputs, outputs, stores and transfers of energy

Front 3

What are the two types of hydrographs and definitions

Back 3

Annual hydrograph/ river regime = shows the variation in a rivers discharge throughout the year usually a mean monthly discharge over a 30 year period

Storm hydrograph

Shows the short term variation in a rivers discharge (usually hours or days)

Front 4

Factors impacting the shape of hydrograph

Back 4

Relief = steep basin slopes will shed water much more rapidly than gentle slopes

Drainage basin size and shape=

Small basin will gather and transfer water rapidly resulting in a short storm flow and short large time but a large basin will take days or weeks slowing down transfer

Soil and geology =

Regions of Impermeable soil and rocks will have a flashy response to rainfall as fast surface flows are dominant

Type of precipitation=heavy and prolonged rainfall will saturate sub surface stores more rapidly, drizzle/gentle rainfall will allow time for precipitation to occur and hail snow will have to thaw before can be transferred

Front 5

Entrainment

Back 5

Process by which particles are removed from a river bed as bedload or suspended load

Front 6

Erosion

Back 6

Wearing away of the bed and banks of the river

Front 7

Erosion

Back 7

Wearing away of the bed and banks of the river

Front 8

H action

Back 8

Erosive power of the water itself

Front 9

Solution

Back 9

Soluble minerals or rock dissolved by water

Front 10

Solution

Back 10

Soluble minerals or rock dissolved by water

Front 11

Abrasion

Back 11

Rock fragments carried by river wear down bed and bank of channel

Front 12

Solution

Back 12

Soluble minerals or rock dissolved by water

Front 13

Abrasion

Back 13

Rock fragments carried by river wear down bed and bank of channel

Front 14

Attrition

Back 14

Wearing down of the river load itself as particles strike each other and bed and banks

Front 15

What does hjulstrom curve show

Back 15

Velocity required to erode, transport or deposit different sized particles

Front 16

What are rapids?

Back 16

Rapids are stretches of fast flowing, turbulent water tumbling over an uneven and rocky shallow riverbed

Front 17

Named example of rapids

Back 17

Celina Rapids, Croatia, river flows over limestone and bands of igneous rock types

Front 18

Pools

Back 18

Faster section where erosion occurs

Deeper areas of efficient laminar flow

Front 19

Pools

Back 19

Faster section where erosion occurs

Deeper areas of efficient laminar flow

Front 20

Riffles

Back 20

Deposition occurs here due to lower velocity

Direct thaweg towards one bank of river channel

Slower sections with uneven bedload resulting in turbulent flow

Front 21

Pools

Back 21

Faster section where erosion occurs

Deeper areas of efficient laminar flow

Front 22

Riffles

Back 22

Deposition occurs here due to lower velocity

Direct thaweg towards one bank of river channel

Slower sections with uneven bedload resulting in turbulent flow

Front 23

How can pools and riffles initiate meanders

Back 23

Riffles direct thaweg towards outer bend where pools enable more erosion of banks