Unit 6 - Managing water supplies

How is water distributed?

How is water distributed?

• Saltwater

• Surface freshwater

• Sub-surface freshwater

• Atmospheric water

Where is surface freshwater found?

Glaciers, lakes, rivers

• Inflows: precipitation, overland runoff, groundwater seepage, & glacial/snow melt

• Outflows: evaporation, infiltration into ground stores, & abstraction by humans

Where is sub-surface freshwater found?

Groundwater, soil moisture, & permafrost

Describe aquifers

Zone of rock saturated with water

• Top of this zone = water table (rises & falls based on input/output)

• Confined aquifers lay below + above impermeable material (aquitards)

  • Unconfined = more susceptible to drought

What is water security?

the ability to access sufficient quantities of clean water to maintain adequate standards of food and manufacturing of goods, adequate sanitation and sustainable health care

How can climate change cause water insecurity?

changes in rainfall because warmer air holds more moisture

• Can cause increased drought, flooding, & decline in snow fall

How can natural disasters cause water insecurity?

Flooding → erosion of topsoil, pollutes water supply (e.g fertilizer), damages sanitation infrastructure

How do pollution events cause water insecurity?

Water pollution: can occur at point source OR misuse of a water source for dumping waste

• Run off of: domestic waste (e.g. sewage), industrial waste (e.g. heavy metals), agricultural chemical & fertilizer run off (eutrophication)

How can groundwater be polluted & cause water insecurity?

Can be contaminated by metals like iron & fluoride

• From: leachate, septic tanks, storm water drains, saltwater intrusion (saltwater moves into freshwater aquifers)

• Salt-water intrusion: over abstraction of freshwater reduce pressure & salt water can enter the aquifer

How can population growth cause water insecurity?

• population increases → demand for water increases

  • more waste & over abstraction of water from aquifers (drops water table + makes them harder & more expensive to access)

    • Impacts flora & fauna: springs + streams that wildlife rely on may dry out & trees that access the water table with deep roots will dehydrate + die

  • Changes in land usage → deforestation & urbanisation

    • Forest + wetlands can act as natural water reservoirs → water can’t infiltrate & recharge groundwater supplies

How can competing demands from agricultural, industrial, and domestic sectors cause water insecurity?

• Industrial: power plants, metal/plastic manufacturing

• Municipal: households (toilet, shower, drinking water)

• Agriculture: water for livestock, irrigation water for crops

  • Most human water use

How can international competition over water sources cause water insecurity?

conflict b/t regions/countries over water access

• Waterways being damned can deprive users of water source

• Some rivers cross int’l borders (e.g. Jordan River b/t Syria/Israel)

How can inequality of water availability cause water insecurity?

people in LICs are less likely to have access to clean drinking water than HICs (can pay for infrastructure for a safe water supply)

How can differing access to safe drinking water in urban and rural areas cause water insecurity?

urban areas have better access to clean water (have financial resources) than rural ones

• Urban areas may face significant water supply problems + impoverished urban areas may not have access to clean water + sanitation

How can mismanagement of irrigation (e.g. salinisation) cause water insecurity?

water supplies can run out & create human-drought conditions

• Overuse of water → soil salinization → salt on top layer & reduces productivity

• Eutrophication, increased turbidity, toxic water pollution, harm to ecosystems + groundwater

How can inadequate sanitation cause water insecurity?

sewage systems + water management plants

• Sanitation mismanagement: changes in supply/demand + aging infrastructure

  • Septic waste contamination → cholera, diarrhea, etc.

What are some impacts of water insecurity?

• Reduced crop yield, crop failure, livestock death

  • food shortages, malnutrition and famine

• Illness from contaminated drinking water

  • Exposure to bacteria in septic waste → cholera & diarrhea

• Poverty: unable to grow food + stay healthy

  • “Poverty trap” = sick person is unable to work & struggles to afford healthcare

How can piped supply manage water insecurity?

Transports water

• Improves access & reduces water insecurity, BUT can be expensive & leaks add to water stress

How can aquifers + artesian wells manage water insecurity?

body of rock/sediment that holds groundwater; well drilled into an aquifer where pressure pushes water out

• Steady supply (none lost to evaporation) & cheap to extract, BUT can get depleted if over-pumped, saltwater intrusion in coastal areas, & difficult to de-contaminate

How can boreholes manage water insecurity?

Narrow hole to locate water

• Affordable, safe water that can be used for non-potable actions, BUT can lead to contamination + be over-extracted

How can gravity-fed schemes manage water insecurity?

Cheap & effective for a smaller sized crop area, BUT not applicable in flat terrain + needs management

How can reservoirs and dams manage water insecurity?

Increasing holding supply can protect water supply during stress

• Cheap electricity, year-round water supply, BUT flooded land destroys land + displaces people, migration and spawning of fish may be disrupted

Ways to reduce domestic water usage:

rainwater tanks, low flow shower heads, low flush toilets, overall awareness

Ways to reduce agricultural water usage:

improved irrigation techniques (e.g. drip irrigation/soil moisture), growing crops less dependent on high water supply

Ways to reduce industrial water usage:

reusing/recycling clean water, upgrading technology to more efficient solutions, routine maintenance (checking for leaky pipes)

How can education on sustainable water use manage water insecurity?

gives people knowledge about their responsibility for their own water consumption

How can poverty reduction manage water insecurity?

population will be healthier, agricultural development/cultivation, & produce manufactured goods (job opportunities)

Water-related aid & int’l agreement examples:

• Water Convention of 1996: established 3 main pillars to promote cooperation b/t nations & ensure fair + secure water usage

• Water aid: aims to ensure a safe water supply → reduce infant mortality + food insecurity

How can rationing manage water insecurity?

Existing resources last longer, BUT doesn’t find an alternative & difficult to manage

How the distillation of saltwater manage water insecurity?

heating saltwater until it evaporates

• Improves access to clean water & cheap, BUT leaves behind waste (brine) and requires an energy sources