4.1 Introduction to Water Systems

Significant Ideas

• The hydrological cycle is a system of water flows and storages that may be disrupted by human activity.

• The ocean circulatory system (ocean conveyor belt) influences the climate and global distribution of water (matter and energy).

Knowledge & Understanding

• 1. Solar radiation drives the hydrological cycle.

  2. Fresh water makes up only a small fraction (approximately 2.6% by volume) of the Earth’s water storages.

  3. Storages in the hydrological cycle include organisms, soil and various water bodies, including oceans, groundwater (aquifers), lakes, rivers, atmosphere, glaciers and ice caps.

  4. Flows in the hydrological cycle include evapotranspiration, sublimation, evaporation, condensation, advection (wind-blown movement), precipitation, melting, freezing, flooding, surface runoff, infiltration, percolation, and stream-flow or currents.

  5. Human activities such as agriculture, deforestation and urbanization have a significant impact on surface runoff and infiltration.

  6. Ocean circulation systems are driven by differences in temperature and salinity. The resulting difference in water density drives the ocean conveyor belt, which distributes heat around the world, and thus affects climate.

Applications & Skills

1. Discuss human impact on the hydrological cycle.

2. Construct and analyse a hydrological cycle diagram.

Guidance

1. The effect of urbanization on water flows and potential of flash floods should be covered.

Key Vocabulary

• XYZ

Textbook Reading and/or Activities

• Pages 198-206

  • To do (p.199)

  • To do (p.201

  • ToK (p.201)

  • To do (p.202)

  • To research (p.202)

  • To do (p.204)

  • To do (p.205-206)

Notes

i-Biology Notes (Not available)

A detailed set of notes, created by Stephen Taylor, examining U1 - U8 and A1 - A4.

i-Biology Study Questions (Not available)

A series of questions, created by Stephen Taylor, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.

Bioknowledgy Notes (Not available)

A detailed set of notes, created by Chris Paine, examining all of the IB learning expectations.

Bioknowledgy Study Questions (Not available)

A series of questions, created by Chris Paine, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.

Learning Activities

Case Study: The Disappearance of the Aral Sea

This article, called "Waiting for the sea" and prepared by Rustam Qobil for the BBC (Feb.25, 2015), outlines how human activities have led to the drying up of the Aral Sea and the impacts this has had on the people of the region (K&U5, A&S1). VIDEO

Case Study: California is Sinking

This article, called "In California, Demand for Groundwater Causing Huge Swaths of Land to Sink" and prepared by Julie Schmit for National Geographic (Mar.26, 2014), outlines how human activities have led to the sinking of the San Joaquin Valley in California due to excessive irrigation for farming (K&U5, A&S1). VIDEO

Activity: Analyzing Human Impacts

This activity uses the two case studies provided above in order to analyze how humans impacts are influencing Earth's water systems.

Supplemental Reading

Protecting Water Quality from Urban Runoff

This reading (5-10 mins), produced by the US Environmental Protection Agency, outlines our need to be responsible for what flows from our homes and streets into nearby water systems.

This video examines the distribution of water resources on our planet and the manner in which they're used by humans.

This video provides some context for the size and importance of the ocean. It also includes some interesting facts.