Exam 3 Flashcards
What is urbanization characterized by
- increase in human habitation
- increase in per capita energy consumption
- extensive modification of the landscape
How is urbanziation defined
- areas with greater than or equal to 50,000 people, and a periurban or suburban fringe with greater than or equal to 600 people per square mile
- greater than 75% of the us population lives in urban areas
What are the 2 main causes of stream impairment
1) agriculture
2) urbanization
How many streams and rivers are impaired by urbanization?
-greater than 130,000 km of rivers and streams
Urban land expansion rates are _______ urban population growth rates
- higher than or equal to
- urban growth is becoming more expansive rather than compact
By 2030, global urban land cover will increase an estimated ____
1.5 million km^2
The most rich countries have low _____
- population density
- more land per person
- suggests that urban land expansion is slowing in these regions
Four ways to measure urbanization
1) Urban land cover
2) Urban population density
3) Fragmentation
4) Compactness
Urban land cover (way to measure urbanization)
-total built-up area of cities, sometimes including open spaces within and on the urban fringe
Urban population density (way to measure urbanization)
-ratio of the total city population to the total built-up area it occupies
Fragmentation (way to measure urbanization)
-relative amount and spatial structure of the open spaces that are fragmented by the expansion of cities into surrounding countryside
Compactness (way to measure urbanization)
-the degree to which the city footprint approximates a circle rather a sprawly shape
the gradient paradigm
- analyzes the ecology of urbanization
- works well because of the common structure of urban areas
Urban-rural gradients
-examines the ecological role of humans
Urbanization produces an array of experimental manipulations such as changes in:
- disturbance regimes
- biota
- landscape structure
- physiological stresses
Physical effects of urbanization in hydrology
- flashier and higher peak flow
- increased runoff
- reduced floodplain inundation
- reduction in permeability/infiltration
Hydrologic effects of increased impervious surface cover
- decrease in infiltration and evapotranspiration
- increase in runoff
- floods reach peak more rapidly
- Reduced groundwater recharge
Stormwater management programs are designed to:
-maintain quality and quantity of stormwater runoff to pre-development levels
NPDES
- National Pollutant Discharge Elimination System
- controls water pollution by regulating point sources that discharge pollutants into waters of the US
Temperature impacts of urbanization
- cities can be warmer than the surrounding country side
- heat island effect
- due to removal of vegetation
______% of urban wastewater in developing countries is untreated
80-90
Chemical pollutants
- heavy metals
- pesticides
- organic contaminants
Bacterial densities are ____ in urban streams. Why?
- higher
- increased fecal bacteria from waste water treatment and sewer effluent
algal diversity _____ as proportion of urban land use inreases. Why?
- increased nutrient/light levels increase algal biomass
- decreases
Macroinvertebrate response to urbanization
-decrease in taxa richness
Adverse effects of N pollution are the result of contributions of these 4 major areas:
1) acidic deposition
2) acidification and overfertilization of forested ecosystems
3) acidification and fertilization of fresh water ecosystems
4) coastal eutrophication
Point sources of nutrients
- wastewater effluent
- runoff and infiltration from animal feedlots
- storm sewer outfalls from big cities
- runoff from big construction sites
Nonpoint sources of nutrients
- runoff from agriculture
- runoff from pasture and range
- land conversion
- atmospheric deposition
What is the most critical element in coastal ecosystems and why
- nitrogen
- drives primary production in estuaries
Eutrophication impacts
- increased biomass of phytoplankton
- dissovled oxygen depletion
- shift in phytoplankton to harmful species
- death of coral reefs
- increased incidence of fish kills
Estuary eutrophication
- N and P loading of freshwater increases eutrophication in estuaries
- global warming may make estuaries switch from N sink to N source
Riparian zone attributes
- structured by dynamic physical drivers
- collection points for resources
- high species diversity, productivity, nutrient recycling
Buffer ecosystem functions and services
- physical (flood attenuation, windbreaks)
- Biogeochemical (nutrient retention)
- Biological (wildlife corridors)
Nutrient retention functions associated with buffers include:
- N fixation
- Microbial immobilization
- Soil storage
- groundwater mixing
Denitrification
- only process within a riparian buffer that removes N from system
- microbial transformation of nitrate to gaseous from allows it to diffuse to the atmosphere
Lakeshore buffer benefits
- nutrient filtration, habitat
- prevents shoreline erosion
Why are salamanders important
- they are a flagship species of riparian zones
- linking aquatic and terrestrial habitats
- one of the best indicator species
Susquehanna river basin compact
-provides the mechanism to guide basin-wide conservation, development, and administration of water resources
Who presented on the NYC water supply
Rene Germain
Where does NYC get its water from?
- Catskill/Delaware watersheds
- Croton watersheds
- water travels up to 125 miles before reaching the city
Cholera Epidemic
- NYC faces growing pains related to water quality and quantity
- 19th century water blues
- recording of zombies
Catskill watershed
- two reservoirs
- supplies about 45% of NYC daily water consumption
- currently unfiltered
Delaware watershed
- constructed 1937-65
- required intervention of the supreme court
- four large reservoirs supplying about 50% of NYC daily water consumption
- unfiltered
Why is the cannonsville reservoir bad
- displaced 5,500 people and claimed 26 communites
- put this whole civilization under water
What are the 2 reservoirs in the catskill watershed
-Schohaire and Ashokan reservoirs
What are the 4 reservoirs in the delaware watershed
- Cannonsville
- Pepacton
- Neversink
- Roundout
Catskill/delaware system
- 1 billion gallons per day
- 9 million residents
- high water quality
Why isnt the catskill/delaware system filtered?
-high forest cover and low urbanization
Why is the NYC watershed unique?
-its primarily owned by private landowners
Who presented on save the rain?
-Madison Quinn
Some ways to save the rain
- green roof
- porous parking lot-runoff diversions
- biorentention
- rain garden
Traditional grey infrastructure
- flood control dams and reservoirs
- levees
- floodwalls
- channel modifications
Flood control dams and reservoirs
- capture and retain incoming flood waters
- release a lower flow rate downstream from controlled spillways
Levees
- river training walls to prevent flooding
- walls are sloped and vegetation cleared to reduce roughness and flood height
Flood walls
- vertical, often made of concrete
- space efficient but expensive
- protect dense or valuable real estate
Channel modifications
- armours banks with rip rap to reduce erosion
- dredging and straightening
Challenges to traditional structural approaches to flood risk reduction
- increasing risks from pop growth, climate change, aging infrastructure
- increased demand for ecosystem services
Principles of a green infrastructure approach
- work with natural processes
- pan and implement flood management with a river basin perspective
Land management methods to retain runoff and floodwaters
- Reforestation
- Agriculture BMPs
- Slowing urban runoff
- Acquiring floodplain land for natural flood storage
Who presented on FloodSmart communities?
-Stevie Adams from TNC
Conversion of natural floodplains can lead to
- at risk development
- reduced or eliminated flood storage of the floodplain
- altered hydrology downstream
Flood smart approach
- watershed approach to floodplain management
- community-specific assessments
- systematic decision making
- combines wide range of expertise with local needs and knowledge
Who presented on urban green infrastructure
Madison Quinn
Interbasin water transfers
- transfer of water from one watershed to another via pipelines, canals, aqueducts
- increases water supply in a receiving watershed
Riparian forest buffers
- designed combinations of trees, shrubs, grasses, and more adjacent to, or within a stream channel
- designed to mitigate the impact of land use on the stream
Wild and Scenic rivers act
- created in response to the glory years of dam building
- 860,000 modified river miles (24% of US rivers)
Wetland delineation
- determination of precise boundaries on the ground through surveys
- requries assessment of vegetation, hydrology, and soils
