The hydrosphere
The water you drink today may once have been, millions of years ago, part of an ocean or a glacier. On Earth, water is never used up or created: it only changes place and state, again and again, following the water cycle.
The planet's water reserves
From space, the Earth looks like a blue sphere covered by vast oceans, yet on land millions of people suffer periodic droughts: how is the planet's water really distributed, and how much of it can we use?
Classify these bodies of water as saltwater or freshwater: the Atlantic Ocean, a glacier, a lake, a river, the Mediterranean Sea, and water from an aquifer.
Classify these bodies of water as saltwater or freshwater: the Atlantic Ocean, a glacier, a lake, a river, the Mediterranean Sea, and water from an aquifer.
Order these water reserves of the planet from largest to smallest amount: rivers and lakes, oceans, ice and glaciers, groundwater.
Order these water reserves of the planet from largest to smallest amount: rivers and lakes, oceans, ice and glaciers, groundwater.
In a debate on sustainability, a municipal representative states: "Given that 71 % of the Earth's surface is covered by water, the fear of water scarcity is unfounded:…
In a debate on sustainability, a municipal representative states: "Given that 71 % of the Earth's surface is covered by water, the fear of water scarcity is unfounded: water is a virtually inexhaustible resource."\na) Using data from the hydrosphere (97,5 % of the planet's water is salt water and only 2,5 % is fresh water; and of that fresh water, 69 % is frozen in glaciers and barely 0,3 % is found in accessible surface rivers and lakes), calculate what exact percentage of the planet's total water is represented by liquid surface fresh water.\nb) Based on your numerical calculation, reasonably refute the representative's statement and predict the hydrological and ecological consequences of managing a region's water resources under the assumption that available water is limitless.
The states of water and the aquifer
Name the three states in which water is found in nature and give an example of each.
Name the three states in which water is found in nature and give an example of each.
Define what an aquifer is and explain why it is an important freshwater reserve for people.
Define what an aquifer is and explain why it is an important freshwater reserve for people.
Where does the water from a spring come from? Relate it to rainfall, infiltration, and aquifers.
Where does the water from a spring come from? Relate it to rainfall, infiltration, and aquifers.
The water cycle
A puddle in the street dries up completely a few hours after the sun comes out, yet the oceans never empty and the air never becomes saturated with water for good: where does all that water travel to, and how does it return to the surface?
The diagram shows the water cycle with five numbered processes. Name the processes labelled 1 to 5 and briefly describe what happens in each.
The diagram shows the water cycle with five numbered processes. Name the processes labelled 1 to 5 and briefly describe what happens in each.
State which process of the water cycle each sentence describes: water vapour turns into droplets and forms clouds; seawater passes into the atmosphere as vapour; water…
State which process of the water cycle each sentence describes: water vapour turns into droplets and forms clouds; seawater passes into the atmosphere as vapour; water falls onto the surface as rain or snow.
Distinguish between surface runoff and infiltration, and state how ground slope and vegetation cover influence each of them.
Distinguish between surface runoff and infiltration, and state how ground slope and vegetation cover influence each of them.
Water and human activity
Two villages receive the same annual rainfall, but one sits on impermeable clays and the other on permeable limestone rock. Compare runoff and aquifer recharge in both…
Two villages receive the same annual rainfall, but one sits on impermeable clays and the other on permeable limestone rock. Compare runoff and aquifer recharge in both cases and reason which one will be at greater risk of flooding.
Seawater is not suitable for drinking or for watering most crops. Explain which process makes it possible to obtain fresh water from it (desalination) and cite one…
Seawater is not suitable for drinking or for watering most crops. Explain which process makes it possible to obtain fresh water from it (desalination) and cite one drawback of that procedure.
After the construction of a housing development with paved streets and impermeable roofs on a forested hillside, technicians find that during heavy rainfall, it takes…
After the construction of a housing development with paved streets and impermeable roofs on a forested hillside, technicians find that during heavy rainfall, it takes only 30 minutes for water to reach the river instead of the usual 4 hours, and that the peak flow rate has tripled, flooding the town located downstream.\na) Justify this hydrological change by analyzing how paving the ground alters infiltration, evapotranspiration, and surface runoff.\nb) To prevent further flooding, a company proposes channeling the river with concrete in a straight line to the river mouth. Critically evaluate this proposal by predicting what will happen in areas located even further downstream, and design two alternative measures based on sustainable drainage or environmental restoration to promote aquifer recharge.