Lecture 4-7 Flashcards
Identify two major water sources for human use in Canada
Surface Water (rivers, lakes)
Groundwater
Challenges with surface water
Seasonal variations impact availability (spring runoff increasing water supply in spring and early summer, but reduced flows during late summer and winter freezing periods limit access)
Vulnerability to climate variability can exacerbate shortages or flooding
Challenges with groundwater
Slow recharge rates, especially in areas with high extraction rates or limited precipitation, leading to depletion over time
Over-extraction in agricultural and urban regions can cause long-term sustainability issues, including lowered water tables and land subsidies
Climate change on water availability in coastal regions
Likely to become wetter due to increased precipitation from warmer air carrying moisture
Risk: Flooding and overflows in reservoirs
Climate change on water availability in inland areas
Likely to become drier as evaporation increases and less moisture is retained over land
Risk: Decreased water availability and great reliance on engineered storage
Feasibility of seawater desalination in Metro Van
High costs and energy requirements, viable only if freshwater sources are exhausted. Produces brine waste
Feasibility of rainwater capture in Metro Van
Inconsistent availability due to seasonal and daily variability, requires storage solutions
Compare Canada’s per capita water demand with other countries
Canada (1000 m3/yr/cap)
Australia (1400 m3/yr/cap)
USA (2500 m3/yr/cap)
What factors contribute to Canada’s relatively high per capita water demand
Misconception of abundant water supply
High domestic and industrial use
Sparse population in water-rich areas
Surface water opportunities and limitations
High flow possible
Surface activities can contaminate the water
Impacted by climate conditions (runoff from rain carries high amounts of suspended solids, turbidity, and pathogens)
Confined groundwater opportunities and limitations
Lower flows possible - limited by soil type - so may not be feasible for large cities
May be high in dissolved material including manganese, calcium, magnesium, iron leached from soil
Difficult to ‘clean-up’ after contaminated
Can take long to replenish once depleted
Natural filtering capacity of soil tends to remove suspended solids, turbidity and pathogens
Unconfined groundwater opportunities and limitations
Inexpensive to dig a GUDI well
GUDI water can generally be replenished rapidly
Characteristics of both surface and groundwater
Rainwater opportunities and limitations
Can be high quality (after first flush)
Can be poor quality (first flush)
Seasonal - requires storage
Seawater opportunities and limitations
Energy intensive to desalinate. Generates a concentrated brine solution that must be disposed
Can be used to prove freshwater when no/limited water sources are available
Why remove NOM if not of concern for human health
Can react with chemicals commonly used in treatment to form by-products. Of particular concern are by-products of disinfection with chlorine. Some Disinfection By-Products (DBPs) are classified as suspected carcinogens, and have been linked to birthing and developmental converns.
What are anthropogenic contaminants
Originate from human activities, including industrial, agricultural, and urban processes
Two examples on anthropogenic contaminants sources
Heavy metals (lead, mercury) from industrial discharges or mining
PFAS from firefighting foams and nonstick coatings
