Topic 4: Water (4.1 Water systems; 4.2 Water access, use, security; 4.3 Aquatic food production systems; 4.4 Water pollution)

Earth’s water budget

• Earth’s water budget = amount of water stored + in water cycle (i.e. on Earth)

  • 70% covered water, ONLY 3% freshwater

  • *most freshwater frozen in ice caps…

What are some examples of water sources?

• RENEWABLE (rivers, streams)

• LESS-renewable (groundwater, aquifers)

  • "aquifer” = porous rock/sediment that HOLDS groundwater

  • *note; aquifers NOT reliable source bc VERY SLOW inflitration.

• NON-renewable (glaciers, oceans)

THE HYDROLOGICAL (water) CYCLE

1. solar radiation, evaporates

2. warm/moist air rises, condensation (clouds!)

3. RAIN.

**other water transfers—

• stores: ex. oceans, soil, aquifers/groundwater, lakes, streams, ice caps

• transferred by: wind, flooding, runoff, soil infiltration

• EVAPOTRANSPIRATION

Evapotranspiration

• Evapotranspiration (EVT) = plant transpiration (lose water vapor thru stomata) + soil evaporation

How do HUMANS IMPACT water cycle?

• domestic use—agriculture, industry

  • nitrate/phosphate runoff = EUTROPHICATION (over-nutrient, cause algal blooms)

  • increased soil erosion (from deforestation, urbanization, etc.) ; ⬆ flooding

• urbanization

  • less evapotranspiration (bc less open ground)

  • pollution from sewage

• DEFORESTATION:

  • increased soil erosion (less roots); turbidity, freshwater/aquifer contamination, flooding

  • LESS Evapotranspiration (less clouds, less recip)

    • EXAMPLES: ex. Aral sea area REDUCED 75% bc river redirection into irrigation, ex. Ganges basin—deforestation=flooding

Define water SECURITY.

• water security = access sufficient CLEAN water to live sustainably

• (most freshwater; rivers, lakes, reservoirs, glaciers, OR groundwater—aquifers; unreliable)

Define water scarcity.

—> nedless to say…water essential for daily life: domestic, agriculture, industry, power generation (i.e. hydro power, cooling systems, etc.)

• A. physical scarcity —> literally NOT enough water

• B. economic scarcity —> no storage/transport systems for water

What FACTORS influence water SCARCITY/availability?

• a. climate = low temps, high rainfall is optimal

• b. geology = more permeable/porous = ⬆ aquifer potential

• c. infrastructure = TREAT water

• d. poverty = no clean water —> sickness, children —> no work/money —> no water

• e. pollution. (esp, agricultural)

• f. “over-abstraction” = more water taken from aquifers THAN REPLENISHED by rainfall.

How do HUMANS impact water sustainability?

• 2 types water issues— (1) scarcity, (2) degradation (of water quality)

• climate change —> disrupts rainfall patterns/cycling + SALINIZATION of groundwater (flooding), evaporation

• deforestation = more soil erosion, less aquifers, less evapotranspiration

  • freshwater contamination; *wastewater literally gets backed into streams

**HOW can humans INCREASE freshwater SUPPLY?

A. ⬆ Freshwater supply (TECHNOLOGY):

• a. dams/reservoirs

  • PROS: save/regulate water + hydroelectric power + flood control!

  • CONS: expensive, disrupts local ecosystems (beavers :c), disrupts groundwater

• b. rain harvesting systems

  • PROS: easy/cheap installation

  • CONS: unpredictable rainfall, lack storage systems, mosquitos polluted

• c. desalination

  • PROS: lots saltwater!

  • CONS: MEGA expensive, uses toxix chemicals (chlorine, etc.)

**How can we CONSERVE water (at home/farms)?

B. Water Conservation (at home/on farms)

• at home…conserve water!

  • a) grey water (lightly used water) to water plants, clean cars, etc.

  • b) water metering = tells people how much water/$$ charge per building (more conscious!!)

• in agriculture:

  • i. drip irrigation —> right into roots of plants (*EXPENSIVE!!)

  • ii. drought-resistant crops; ex. alfalfa, cucumbers, rice

  • iii. AQUAPONICS?? fish circling plants

  • iv. vertical farming (less evap, recirculating water)