Test 2.2 Human Impacts

Question 1

Name 7 uses of water

Answer 1

• Public & private water supply
• Agriculture
• Electricity: hydropower and cooling
• Fish farming
• Water cress growing
• Amenity ponds
• Water treatment & transport

Question 2

What are the % proportions of global water usage?
Agriculture
Domestic and industrial
Power
Evaporation from reservoirs

Answer 2

Agriculture 67%
Domestic and industrial 20%
Power 10%
Evaporation from reservoirs 3%

Question 3

Reasons for channel modification

Answer 3

-Flood control
-Erosion control
Navigation
-Urbanisation
-Reclocation

Question 4

What is a culvert

Answer 4

Underground tunnel carrying a stream e.g. river Westbourne

Spaghetti junction river tame

Question 5

Characteristics of natural channels

Answer 5

Meandering
Riffle/pool structure
Erosion/ deposition features
Rich riparian vegetation
-High inputs of CPOM
-Terrestrial invertebrates
-Shading

Question 6

Characteristics of modified channels

Answer 6

Straightened

• shortened
• increased slope?

Loss of riffle/pool structure
-Mainly shallow riffle/run

Reinforced banks

• Reduced erosion/deposition
• Loss of undercut banks: fish habitats

Loss of heterogeneity

e.e. River Rhone

Question 7

Difference in riparian zone characteristics between natural & modified channels

Answer 7

Natural: Rich riparian vegetation

• High inputs of CPOM
• Terrestrial invertebrates
• Shading

Modified: Loss of riparian zone

• Reduced CPOM & LWD
• Reduced cover for fish
• Reduced shade: more variable temperatures extreme low DO

Question 8

Difference in diversity of habitats under different flow conditions

Answer 8

Natural high flow:
Diversity of water velocities high in pools, lower in riffles
Resting areas abundant beneath undercut banks role of large rocks

Natural low: sufficient water depth to support fish and other aquatic life in dry season

Modified high: May have higher velocity than some aquatic life can withstand. few or no resting place

Modified low: Insufficient depth of flow during dry season to support aquatic life

Question 9

Difference in infiltration through soil characteristics between natural & modified channels

Answer 9

Natural: Infiltration through soils
-water percolates through soils and groundwater

Modified:
Hard surfaces
Focussed inputs to river through storm drains
-Increases rate of runoff
-Increased sediment; pollutants

Question 10

Difference in drainage path characteristics between natural & modified channels

Answer 10

Natural:
Many points of entry of water into stream after soil filtration

Modified:
Runoff rain travels through storm drains to stream- mobilises pollutants and sediment

Question 11

What is the difference between peak rainfall and peak discharge in natural and modified streams?

Answer 11

Peak discharge is closest to peak rainfall in modified channels. Occurs earlier

Higher peak flows

Lower base flows

Question 12

Definition of pollution

Answer 12

A contaminant of river water that causes real or potential harm to human health, damage or harm to non-human nature without justification

Question 13

1st main sources of River Pollutants

Answer 13

1. Urban wastewater

Sewage treatment works (STWs)
Combined sewer overflows (CSOs)
Misconnected sewers

Sewage contains organic material plus soaps (high in P), heavy metals and other pollutants

Question 14

2nd Main sources of River Pollutants

Answer 14

2. Agricultural Wastes

Slurry
Silage clamps
Dairy washings
Disinfectants
Pesticides
Fertilisers

Question 15

3rd Main source of river pollution

Answer 15

3. Industrial waste