1 - Water processes & terminology

Question 1

percolation

Answer 1

Slow movement of water through spaces and joints in underlying rock (down)

Question 2

What is a drainage basin?

Answer 2

An open system with inputs (e.g., precipitation), outputs (e.g., evaporation, transpiration), flows, and stores.

Question 3

What is precipitation in the context of a drainage basin?

Answer 3

Input into the drainage basin system; can vary by type (rain, snow) and intensity.

Question 4

What is evaporation?

Answer 4

Output from the system where water is converted from liquid to vapor.

Question 5

What is transpiration?

Answer 5

Output where water vapor is released from plants into the atmosphere.

Question 6

What is infiltration?

Answer 6

Flow process where water enters the soil from the surface.

Question 7

What is throughflow?

Answer 7

Flow of water within the soil, moving downhill through pores and spaces.

Question 8

What is overland flow?

Answer 8

Water flowing over the land surface when the soil is saturated or precipitation exceeds infiltration.

Question 9

What is base flow?

Answer 9

Groundwater flow that feeds into rivers during dry periods.

Question 10

What are stores in a drainage basin?

Answer 10

Parts of the basin where water is held, including vegetation, soil, aquifers, and cryosphere (frozen water).

Question 11

What is river discharge?

Answer 11

The volume of water flowing in a river per unit time (usually m³/s), linked to stream flow and channel size.

Question 12

What is stream flow?

Answer 12

The movement of water through a channel, influenced by discharge and velocity.

Question 13

What are channel characteristics?

Answer 13

Features such as width, depth, bed roughness, and slope, affecting river flow and processes.

Question 14

What is hydraulic radius?

Answer 14

Ratio of the cross-sectional area of a river to its wetted perimeter; indicator of flow efficiency.

Question 15

What are river erosion processes?

Answer 15

Include hydraulic action, abrasion, attrition, and solution.

Question 16

What are river transportation processes?

Answer 16

Include traction, saltation, suspension, and solution (movement of eroded materials).

Question 17

What is river deposition?

Answer 17

The laying down of sediment when the river’s energy decreases.

Question 18

What are channel characteristics that influence processes?

Answer 18

Affect erosion and deposition; include slope, roughness, and discharge.

Question 19

What is seasonality in river systems?

Answer 19

Seasonal changes (e.g., rainfall, snowmelt) affect river flow, erosion, and sediment transport.

Question 20

What is a waterfall?

Answer 20

River landform where water drops vertically due to resistant rock overlying softer rock.

Question 21

What is a floodplain?

Answer 21

Flat area around a river that floods periodically, formed by deposition.

Question 22

What is a meander?

Answer 22

A bend in a river formed by lateral erosion and deposition.

Question 23

What is a levee?

Answer 23

Natural or artificial embankments along a river, built up by repeated flooding and sediment deposition.

Question 24

What is a delta?

Answer 24

A landform at the river mouth where sediment is deposited as the river meets standing water.

Question 25

Hydrograph

Answer 25

A graph showing how a river's discharge changes over time after a rainfall event.

Question 26

Lag time

Answer 26

The delay between peak rainfall and peak discharge on a hydrograph.

Question 27

Peak discharge

Answer 27

The highest flow in the river following a rainfall event.

Question 28

Base flow

Answer 28

The normal day-to-day discharge of the river, supplied by groundwater.

Question 29

Geology (impact on hydrograph)

Answer 29

Permeable rocks reduce runoff and lengthen lag time; impermeable rocks increase runoff and peak discharge.

Question 30

Seasonality (impact on hydrograph)

Answer 30

Seasonal factors like snowmelt or monsoon rains influence flood risk and hydrograph shape.

Question 31

Urbanization

Answer 31

Increases surface runoff due to impermeable surfaces, raising flood risk.

Question 32

Deforestation

Answer 32

Reduces interception and infiltration, increasing flood frequency and magnitude.

Question 33

Channel modification

Answer 33

Altering river channels (e.g., straightening or deepening) which can increase or decrease flood risk depending on context.

Question 34

Flood risk

Answer 34

The likelihood and impact of a flood event, affected by both physical and human factors.

Question 35

Flood prediction

Answer 35

Forecasting floods using data, models, and weather predictions.

Question 36

Weather forecasting

Answer 36

Predicting rainfall and weather events that can lead to flooding.

Question 37

Uncertainty in climate modelling

Answer 37

Climate models have limitations in predicting extreme weather and future flood risks.

Question 38

Flood mitigation

Answer 38

Measures to reduce the impact or likelihood of flooding.

Question 39

Structural flood mitigation

Answer 39

Physical constructions like dams, levees, channel modifications, and afforestation to control floodwaters.

Question 40

Afforestation

Answer 40

Planting trees to increase interception and reduce surface runoff.

Question 41

Levee strengthening

Answer 41

Improving levees to contain more floodwater and reduce overflow.

Question 42

Planning measures

Answer 42

Non-structural approaches like insurance, flood warning systems, and personal flood preparation.

Question 43

Flood warning technology

Answer 43

Systems that alert communities to incoming floods to allow preparation or evacuation.

Question 44

Water table

Answer 44

An underground boundary between the soil surface and the area where groundwater saturates spaces between sediments and cracks in rock

Question 45

Interception storage

Answer 45

storage of water above the ground surface, mostly in vegetation

Question 46

Condensation

Answer 46

the process of gaseous water (water vapor) turning into liquid water

Question 47

Channel flow

Answer 47

the movement of water within the river channel, aka. discharge

Question 48

Channel precipitation

Answer 48

the moisture falling directly on the water surface

Question 49

Stem flow

Answer 49

the flow of intercepted water down the trunk or stem of a plant

Question 50

attrition

Answer 50

Attrition is a process of erosion where rock particles hit against each other, breaking into smaller, smoother, and rounder pieces over time.

Question 51

abrasion

Answer 51

Abrasion is a type of erosion where rock fragments scrape, grind, or rub against a surface, wearing it down like sandpaper. It’s sometimes called corrasion in older texts.

Question 52

solution

Answer 52

Solution (also called corrosion in some texts) is a type of chemical erosion where soluble minerals dissolve in water.

Question 53

hydraulic action

Answer 53

Hydraulic action is the erosion that occurs when the force of moving water compresses air in cracks of rock, causing the rock to break apart over time.