Chapter 4
Sustainable Management of Water
Unit 1
How Do Variations in Precipitation
Affect the Availability of Water?
- the amount of precipitation that an area receives will determine how much water is available.
This may result in:
What are Floods?
- an overflow of a large amount of water onto what is normally a dry land
- e.g. flash floods, river floods
What are Droughts?
- a long period of little or no rainfall in a specific area
- may last for months or even years, causing areas to become drier than normal
- there may not be enough water available to replenish the amount used for human activities or lost through evaporation and transpiration
- reservoirs and groundwater will start to dry up
River Floods
- caused by sustained heavy rainfall or meltwater
- the large amounts of rainwater and meltwater enter streams and tribunaries, which then flows into rivers
- the water level in the river rises rapidly and eventually overflows the banks, flooding the surrounding areas
Flash Floods
- caused by exceptionally heavy rainfall over a short period of time
- often occur in dry areas where there is not enough soil of vegetation to allow rainwater to infiltrate the ground
- most of the rainwater becomes surface runoff which quickly floods low-lying areas
Unit 2
How Does Water Support River Ecosystems?
- precipitation provides a regular supply of water to rivers so that organisms can live in them
Food Chain
- shows the relationships among organisms as energy is transferred through food
- phytoplankton → zooplankton → insects → fish → humans
Unit 3
How Do People Use Water?
- domestic
- recreation
- agriculture
- industry
How is Water Used for Domestic Purposes?
- using water for household activities
- e.g. bathing, cooking and flushing the toilet
How is Water Used for Recreation?
- water sports are highly dependent on water conditions and water quality
- e.g. canoeing, sailing and sport fishing
How is Water Used for Industry?
- to cool equipment in factories and power plants because they generate a lot of heat when they operate
- to generate electricity when it passes through turbines installed in dams
- as a cleaning agent in water fabrication (process of creating components for the electrical circuitry found in computers and mobile phones
How is Water Used for Agriculture?
- accounts for the largest use of water worldwide
- to grow crops and rear animals for human consumption
- different animal and plant products require different amounts of water
Unit 4
How Do Human Actions Lead to Water Pollution and Its Associated Impact?
- human activities often cause water pollution
- water pollution occurs when harmful substances enter water bodies and cause water quality to fall
water pollution poses a threat to aquatic ecosystems - pesticides and lead kill plants and poison animals
Unit 5
How Can Water Be Managed Sustainably?
Countries around the world have attempted to manage water resources by:
- improving water quality
- reducing water consumption
- improving water technologies
- importing water
How Do Countries Improve Water Quality?
- water quality is determined by temperature, amount of dissolved oxygen, turbidity and pH
- these factors affect how well aquatic plants can grow and the range of aquatic animals that can survive
- countries implement laws to maintain or improve water quality
- e.g industries are not allowed to release wastewater into water bodies without permission from the NEA
How Do Countries Reduce Water Consumption?
- water consumption increase as a country's economy and population grow
- raise awareness and promote water conservation with the community, schools and businesses
- e.g. Water Efficiency Labelling Scheme (WELS) grades water appliance with a tick rating (water-efficient products)
How Do Countries Improve Water Technologies?
- using technology to develop new ways of producing and conserving water
- e.g. "Four National Taps" - water from local catchment, imported water, NEWater and desalinated water
- use of artificial intelligence to treat wastewater - machine first analyses how polluted the wastewater is and then suggests the most effective method to treat it
How Do Countries Import Water?
- SG imports water from MY (agreements will expire in 2061)
- Kuwait imports water from Serbia due to its dry climate
NEWater and desalinated water
- reliable water sources that do not depend on the weather
- helps SG better cope with the threat of climate change
- through desalination, PUB turns seawater into drinking water using advanced membrane technolgy
- SG has four desalination plants
- e.g. Keppel Marina East Desalination Plant
Desalination
- Step 1 - Pre-treatment
Seawater undergoes screening and filtration to remove fine particles and microorganisms
- Step 2 - Reverse Osmosis
Pre-treated water is pumped at high pressure through semi-permeable membranes to separate dissolved solids
- Step 3 - Condition + Disinfection
Water is disinfected, re-mineralised and made potable by adding chemicals (chlorine and fluoride)