Option A Drainage Basin System 24e5089a60c74cf98fee1b1f3121e0e4

Drainage Basin System

A system where water is stored after elements of the water cycle, such as rainfall, surface runoff via rivers, and groundwater.

Tributary

Small links that run into the main river.

Confluence

The point where tributaries meet the main river.

Throughfall

Water that falls through gaps in vegetation or drops from leaves and twigs.

Stemflow

Water that trickles along twigs and branches and finally down the trunk of a tree.

Overland flow

Water that flows over the land's surface, occurs when precipitation exceeds infiltration or when the land is impermeable or saturated.

Channel flow

Movement of water in channels such as streams and rivers.

Infiltration

When water soaks into the soil.

Percolation

Water moving into rock.

Throughflow

Water flowing through soil.

Baseflow

Flow of water in a river due to groundwater seeping into the bed of the river.

Interception

Water that is caught by vegetation.

surface stores

Temporary stores such as puddles, and permanent stores such as lakes.

Groundwater

Subsurface water.

Evaporation

Process by which a liquid is changed into a gas.

Transpiration

Process by which water vapor escapes from living plants into the atmosphere.

Evapotranspiration

Combined effects of evaporation and transpiration.

Erosion

The wearing away of rock and soil found along the river bed and banks.

Abrasion

Wearing away of the bed and banks by sediment or flow (moving rocks).

Attrition

Erosion caused when rocks and boulders transported by the river bump into each other.

Hydraulic power

Water compresses pockets of air in the bed, cracks widen and break rock.

Solution

Soluble particles are dissolved into water.

Traction

Heavy rocks and boulders are rolled along the river bed.

Saltation

Small stones/pebbles are bounced along the river bed.

Suspension

Small particles of sand or clay are suspended in the water.

Deposition

The laying down of sediment by a river.

Meander

A u-turn in water.

rivercliff

A cliff formed along the river bank.

Waterfall

A cascade of water falling from a height.

bedload

large chunky rocks

alluvium

fertile, mineral filled soil

bluff

edge of the floodplain, formed by sediment

levee

formed in the lower course due to deposition and repeat flooding. during flooding, deposits course material to form a bank

Interception Loss

Water retained by plant surfaces and later evaporated or absorbed by plant

channel storage

all water stored in rivers and streams

meandering channel

river channel with twisty curves

braided channel

river channel with small, temporary islands

straight channel

very rare, thalweg moves side to side, large amounts of sediment

discharge

amount of water in river

rising limb

rate of discharge rising in river

falling limb

rate of discharge decreasing in river

peak discharge

maximum discharge in river during flood

lag time

time between peak rainfall and peak discharge

baseflow

average river height

laminar flow

Water flows in sheets (laminae) parallel to the channel bed. It requires a smooth, straight river channel with a low velocity. Rarely occurs.

turbulent flow

Water flows in irregular patterns. This occurs when a river has a complex channel morphology and a high velocity. Bed roughness also creates turbulence.

helicoidal flow

Water flows in a corkscrew motion (not down the centre).◦ This is due to alternating pools (deeper parts) and riffles(shallow parts).◦ This flow forms meanders.

aquifer

Rocks containing significant quantities of water, and are permeable rocks such as sandstone and limestone

groundwater recharge

Occurs due to infiltration and percolation from above, seepage from surface water such as lakes, artificial recharge from reservoirs, irrigation, etc.

groundwater losses

Occurs due to evapotranspiration where water table is close to surface, seepage into rivers, leakage into other aquifers, artificial abstraction for irrigation and human use

field capacity

Refers to the maximum amount of water that soil can hold against gravity after excess water has drained away. It represents the soil's ability to retain water for plant use.

infiltration capacity

Theoretical maximum amount of water that soil could hold

wilting point

Refers to the moisture level in soil at which plants are unable to extract water effectively, leading to wilting and potential damage. It is the point at which the soil moisture is so low that the plant's roots cannot access enough water to sustain normal growth and function.

hortonian flow

Surface runoff of water that occurs when the soil is saturated and unable to absorb any more water.

arcuate delta

fan shaped, wave dominated, shaped by longshore drift

cuspate delta

wave dominated, tooth shaped, shpaed by opposing water movement

bird’s foot delta

river dominated, grows out from the shore