Water Sources & Supply (Cambridge (CIE) IGCSE Environmental Management): Flashcards

False.

Infiltration moves water from the surface into the soil; the transfer from the soil into the rock is percolation.

Throughflow transfers water through the soil between the surface and the water table.

Surface run-off (overland flow) is any water flowing across the Earth's surface.

Transpiration releases water vapour from plant leaves into the atmosphere.

Evaporation is the change of water from a liquid to a gas (water vapour) due to heat from the sun.

Higher temperatures and strong winds increase evaporation.

False.

Condensation changes water vapour into liquid water droplets as it cools, and these droplets form clouds.

Fresh water is water with a low salt content that people use for drinking, washing, farming and industry.

False.

Only a small percentage (about 2.5%) of Earth's water is fresh; the rest is saline.

The four main sources of fresh water are the atmosphere, surface water, groundwater and desalinated ocean water.

Many regions depend on seasonal rainfall for drinking water, farming and filling reservoirs.

Meltwater from mountain snow feeds rivers and provides water during dry periods.

Surface water is fresh water found above ground, such as in rivers, lakes and reservoirs.

People use rivers for drinking water, irrigation and hydroelectric power.

Lakes provide a reliable supply because they store large amounts of water in natural basins throughout the year.

A reservoir is an artificial lake created by building a dam.

Reservoirs store water, which helps them control flooding and maintain water supply during droughts.

An aquifer is an underground layer of rock that holds water.

Aquifers refill when rainwater soaks into the ground.

False.

Aquifers provide clean, filtered water, but groundwater is hard to access because it lies below the Earth's surface.

A well is a hole dug or drilled into the ground to reach an aquifer.

Desalination plants are usually found in coastal areas where freshwater supplies are limited.

False.

Desalination provides a reliable supply, but it uses large amounts of energy.

An ocean is a very large expanse of sea.

False.

Oceans are expanses of saltwater, not fresh water.

Oceans represent the main areas into which the sea is divided geographically.

The five recognised oceans are the Pacific, Atlantic, Indian, Arctic and Southern Oceans.

False.

Seas are smaller areas of water than oceans.

Seas are often partially enclosed by land.

Recognised seas include the Black Sea, the Irish Sea and the Caribbean Sea.

False.

The Mediterranean is a sea, not one of the five recognised oceans.

Potable water is water that is safe to drink because it contains no harmful microorganisms or toxic chemicals.

Safe drinking water helps prevent diseases such as cholera and diarrhoea.

False.

Filtration comes first and produces much clearer water; chlorination is the final disinfection stage.

Screening uses metal bars or meshes to remove big objects such as leaves, sticks, plastics and rubbish.

In sedimentation, heavy particles sink to the bottom of settling tanks and form a layer of sludge.

During filtration, water passes through layers of gravel and sand.

Activated carbon can remove chemicals and odours from water.

Treatment plants add chlorine to kill harmful bacteria and viruses.

False.

Chlorine continues to protect the water as it travels through pipes to homes and buildings.

The availability of potable water depends on climate, population, infrastructure and access to sewage treatment.

A water-rich region has high rainfall, many rivers or large lakes.

A water-poor region has low rainfall, a dry climate or frequent droughts.

False.

Water-rich regions can still face shortages because pollution events contaminate their water sources or because of poor water management.

Urban regions often have better access because cities usually have piped water systems, treatment plants and sewage networks.

Rural sources such as wells, rivers and unprotected sources are more easily contaminated and may not be treated.

Low-income countries may lack infrastructure for pumping, treating or storing water.

Desalination is the process of removing salt from seawater to produce potable (safe-to-drink) water.

During distillation, the salt does not evaporate, so it stays behind in the liquid while the water turns to steam.

In distillation, the steam is cooled and condensed so that it turns back into liquid fresh water.

Reverse osmosis is a desalination method that uses high pressure to force seawater through a partially permeable membrane.

False.

The membrane lets small water molecules through but blocks salt ions and most other dissolved substances.

Brine is the very salty waste water left over from desalination.

Desalination plants must dispose of brine carefully because it can harm marine ecosystems.

False.

Desalination draws on the ocean, which is a constant supply, so drought does not affect it.

Desalination is expensive to run because it needs large amounts of energy, especially distillation, which heats the water.

Reverse osmosis membranes need regular cleaning or replacing, which increases costs.

Desalination can help a country depend less on imported water and overused rivers.

False.

Building and maintaining desalination plants is costly, so not all countries can afford the infrastructure needed.

A multipurpose dam is a large dam built to provide several different services from a single reservoir.

Dams hold back excess water during heavy rainfall and release it slowly and safely through controlled channels.

Water released from a dam turns turbines, which spin a generator to produce electricity.

Dams direct reservoir water into irrigation canals or pipes, giving farms a steady supply in dry periods.

False.

Reservoirs create calm, deep water suitable for boat transport and can replace rivers that are too shallow or fast-flowing.

Dam tourist attractions provide jobs and income for nearby communities.

Aquaculture is fish farming, for example raising fish in cages or designated areas of calm reservoir water.

Reservoirs provide space for boating, fishing and swimming.

Multipurpose dams supply renewable electricity, which reduces reliance on fossil fuels.

Multipurpose dams encourage regional development by improving water and energy security.

False.

Dams trap sediment behind the dam, so less nutrient-rich silt reaches farmland downstream.

Flooding land for a reservoir can force people to relocate from their homes.

Flooding land to create a reservoir may destroy wildlife habitats.

Reduced river flow harms ecosystems and affects communities that depend on the river.

False.

If poorly managed, a dam can make sudden releases of water that cause downstream flooding.

Multipurpose dams are very expensive to build and maintain, so not every region can afford one.