Teacher background information
There are many different types of rain: mist, pouring rain, drizzle, deluge, light rain and heavy rain.
Rainfall (precipitation) has decreased in WA’s South West over the past 30 years, and therefore reduced the volume of available water in our dams. Traditionally, Perth has relied heavily on dams as a water source, but today they account for just a third of our water supply.
Water supply in the Perth metropolitan area comes from dams (surface water), under the ground (groundwater) and desalination. As rainfall and stream flows continue to decline, we’re increasing our use of climate independent sources, such as desalination, groundwater replenishment and other forms of water recycling, in order to secure our water supply for the future.
The climate in Australia is changing, with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) predicting that some parts of Australia will become wetter and other parts (e.g. South-Western Australia) drier.
In drier climates such as ours, water evaporates more readily. We should not water the garden during the hottest part of the day, as the water evaporates instead of draining into the ground and reaching the roots of plants and, eventually, groundwater.
Water and the environment
It is important for students to understand that the natural environment also needs water. The water cycle is disrupted when, for example, we surface an area with bitumen instead of leaving it in its natural state and letting water soak into the ground. You should also emphasise the need to protect our water sources from pollution. E.g. protecting catchment areas by preventing chemicals and fertilisers from entering the drainage system.