14. Urban Issues Flashcards
where do most damage to water systems come from?
Our demands and uses for water, agriculutre, land
What are some common uses to fresh water
Public and private water supply, agriculture, hydropower, treatment and transport
Globally what is the most use of water
Agriculture
How much of the worlds water usage is in agricultre?
67%
What are the main habitation alteration subfactors?
Hydrology, Siltation, Alteration of riparian corridor
Which river animals are most vulnerable to human actvities?
Snails, mussels, crayfish
Why might we want to modify a channel?
Flood control, navigation, urbanisation, relocation
Why do a lot of large rivers modify for navigation?
To allow large rivers upstream
Why might we need to move the river
if we want to build something we need to move the building out of the way
When did modyfiing rivers start in china?
600bc
In denmark how many rivers are modified?
98%
Why might streams be modified in cities?
To manage rivers away from a city centre or to make room for other aspects
What happened with rivers in london?
A lot of rivers, hidden or moved, rivers in tanks
What is daylighting?
Opening up underground rivers
What are the characteristics of a natural channel
meandering, riffle pool system, erosion, deposition
In a natural channel where will the erosion take place?
ON the outside of the river channel
WHat are riffles
Area of fast flowing turbulent water
What happends when a river is modified
Normally straightened, rivers are shorter, now roffle pool structure, banks reinforced to stop erosion
What is lost in modified rivers?
Lost of heterogeneity in rivers, with loss of fish refuges
What happened to the river rhone?
Channel deepened and width reduced
What happens when we loose channel width?
Loss of wetlands and riparian edge habitats
By loosing its meanders what happened to the Willamette river?
Became a much more simple system, reducing total length and mass
why is riparian vegetation important in natural systems
shading and allothocranous carbon
Why does a man made channel see less CPOM?
Normally open, also less shading so more variable river channel, reduced fish cover
What does a natural river normaly have?
Much more biodiversity within the river, unifrom flows, also no refuge from high flows
In natural rivers why is it better in summer?
Tend to be deeper allowing area for fish to swim
Why do natural rivers have more connection with the soils
Soil infiltration into the river, man made rivers may not allow this
Why do man made rivers have more focused entrance point?
Drains move water directly into the river, much more peaky flow
What happens with peak flows in man made rivers?
Higher and faster, lower base flows
What is water pollution?
A contaminant of river water that causes real or potential harm to human health or welbeing without justification
what is the most polluting pollution?
Urban waste waters, STW, combinedsewage overflows
WHat does this urban waste contain?
Organic material, plus soap, heavy metal and other pollutions
Why may raw untreated water go into the river system?
CSO’s overflows
WHat are the main types of agricultural waste?
SLurry silage clamps, dairy washers
What are the main transport pollutants?
De icer runoff, roas waste and storm drain effluent
Why is light pollution important on rivers?
Drift of invertebrates, patters of aquatic insects
Which organic pollutants can act as susbtrate for micro organisms?
Proteins, carbohydrates, Fats
What is the biochemical oxygen demand?
Amount of oxygwn consumed by micro organisms in decomposing organic matter
How long does it take for water in the uk to get to the see
5 days
What is the standard test for BOD
oxygen consumed over a 5 day period
What are major cause of deaths with rivers,
cholera
WHo created the polluted waters diagram
noel hynes
What happends to the BOD as the river goes downstream?
Goes down
WHat happens to the oxygen in stage a after a pollution area
drops suddenly, then gradually increases
How much oxygen can sewage fungus siurvive on?
3-6g
When do the algae start to form?
Middle of stage 3, green filiments algae
What is a tubificadae?
Red worm
Why are fish less vulnerable to pollution?
Can move away from the poluution
Where do fish tend to appear
, chlodiophera
Why is sewage an age old problem
big expansion in population led to many diseases and sewerage system
when did the untreated pollution start going into the thames
1800
When was the great stink
1858
When was the last salmon caught in the thames
1833
What happened in london in 1965
sewers diverted under the city out to sea, still no fish
What is the main sewage plant in london?
Beckton sewage works, 3,4 million households everyday
When were salmon re introduced into the thames
1980’s
how many returning salmon was there in 1993?
383
What is the major tideway tunnel project in london?
The lee tunnel
how many fish species does the thames support
125 fish and 400 invertebreates
Which group in the uk monitors rivers
the environment agency monitors all the main river sites
What does the eu say about monitoring freshwaters
all freshwaters have to be monitored
Which animals have been used most as an environmental monitor
macroinvertebrates
what is the common macroinvertebrates index?
Trent biotic index
How much water is evaporated from resivours?
3%
Which rare caddis lived only in a man made river near UOLoughborough,
Tinodes Pallidulus
What rivers run under spaghetti junction?
Tane
What is lost in an urban stream?
CPOM
What is the BOD of natural water systems?
<10mg/l
What is raw sewage BOD?
200-800mg
When will fishes move out of areas with low oxygen?)
When it’s less that 5mgl
