Geomorphology

Question 1

What is a catchment area?

Answer 1

The drainage area that supplies water to a river

The water comes from rainwater, which flows down the slope and from underground water which seeps into the river

Question 2

Drainage basin

Answer 2

Area drained by a river system

Question 3

Watershed

Answer 3

High ground separating one drainage basin from the adjacent drainage basin

Question 4

Confluence

Answer 4

Point where one river in the network joins another

Question 5

Interfluves

Answer 5

Ridges of high ground between individual channels

Question 6

Types of rivers and their description (4)

Answer 6

• Permanent: receive groundwater all year
• periodic: groundwater only in the rainy season (flow for 5-6 months after rain)
• Episodic: no underground water (flow for a few hours after rain)
• Exotic: flow all year (more water at source, less as you move away)

Question 7

What factors affect drainage density?

Answer 7

• high evaporation rates = lower DD
• high rainfall regions = high DD
• large amount of infiltration = lower DD
• hardness of rock - channels in soft rock = higher DD

Question 8

What is stream order?

Answer 8

The category of a stream in an network determined by the order of the streams feeding into it.

Question 9

What is discharge of a river?

Answer 9

The amount of water flowing in a river channel past a point at a given time

Question 10

Laminar flow

Answer 10

Water flowing in sheets; it does not change levels

Question 11

Turbulent flow

Answer 11

Water flowing in a bubbling motion; it changes levels

Question 12

Headward erosion

Answer 12

A river lengthens its course by cutting back upstream above its original course

Question 13

Graded river

Answer 13

A river that has achieved equilibrium between its gradient, volume and channel shape, so that the river has sufficient energy to flow, with erosion rates in balance with the deposition rates

Question 14

Overgraded river

Answer 14

River that has excess energy and therefore erode their channels

Question 15

Undergraded river

Answer 15

Rivers that do not have enough energy to flow and to transport their load; they will deposit some of their load

Question 16

What is a rejuvenated river?

Answer 16

A river receives additional energy and begins to erode vertically

Question 17

Fluvial landforms resulting from rejuvenation

Answer 17

• valley within a valley
• river terraces
• knickpoint waterfalls
• entrenched and ingrown meanders

Question 18

Superimposed drainage pattern

Answer 18

A river develops a pattern on a surface that has eroded over time, so now the river is flowing on the older rocks or structures that have been uncovered

Question 19

Antecedent drainage pattern

Answer 19

After the river formed, folding or faulting occurred, but the river maintained its pattern, cutting a gorge through the land that has been uplifted

Question 20

The importance of water sources

Answer 20

• fresh, clean water supply is essential for human health
• rely on water for many activities (agriculture, industry, hydroelectricity)
• birds and wildlife depend on rivers and vegetation in the riparian zone

Question 21

The importance of wetlands

Answer 21

• remove harmful bacteria
• reduce the acidity of water
• wetlands act as a sponge - reduces flood damage and ensures a steady supply of water all year

Question 22

Why drainage basins and catchment areas need to be managed

Answer 22

• everyone can have access to water
• river ecosystems remain healthy
• flooding can be controlled

Question 23

Impact of people on drainage basins and catchment areas

Answer 23

• human activities pollute groundwater
• over-grazing decrease infiltration of water
• runoff is polluted and harms the aquatic life
• impermeable surfaces (concrete and tar) creates a decrease in infiltration and water flowing over land increases

Question 24

Catchment and drainage basin management

Answer 24

• avoid construction on the flood plain
• educate farmers on environmentally sustainable farming practices
• maintain vegetation in the riparian zone
• conserve and restore wetlands
• make public aware of the need to conserve water