Current scientific conceptions
A catchment area or basin is land which is bounded by natural features such as hills or mountains, from which all run-off water flows to a low point. Simple analogies may be water in a bathtub flowing to the plug hole, or water that falls on a roof flowing to a down pipe. In the case of a natural catchment area, the low point could be a dam, a location on a river, an inland lake, or the mouth of a river where it enters the ocean. A single ridge defines a catchment’s boundary.
Catchment areas vary in size and make-up. Large catchment areas such as those drained by the Fitzroy and Burdekin Rivers are bordered by mountain ranges and include major drainage networks of creeks and rivers. Large catchment areas are made up of hundreds of smaller sub-catchment areas. These may be bordered by low hills and ridges and drained by only a small creek or gully.
What is in a catchment area?
A range of natural resources and land uses will be found in a catchment area from the headwaters to the mouth of the river, but these may vary greatly. Some of the following may be found:
- natural vegetation
- crops and pastures
- domestic animals
- recreation facilities
- National Parks
- forestry areas
- irrigation systems
- sewage system
- cities and towns
- transport routes
- windmills and pumps
Water movement in a catchment area
Water is the linking factor in a catchment area. The water cycle is shown in the following figure. The sun’s energy enables the transfer of water from the sea to the atmosphere in the form of water vapour. This process of evaporation also takes place on land. Plants add water vapour to the atmosphere through transpiration. People, animals and machines add small amounts of water vapour as well, by means of respiration and combustion. The water vapour condenses then falls as precipitation. This may be in the form of rain, snow, sleet or hail. Some precipitation evaporates while falling and returns to the atmosphere. Most precipitation soaks into the soil (infiltration). Part of it sinks to the watertable. This underground water is called groundwater. Any excess water runs off the land and is carried away by streams and rivers (surface run-off). The sun evaporates some surface water. Some underground water is taken up and then transpired by plants.
Health of catchments
All land in Australia is part of a catchment, regardless of whether is it a desert or a swamp, Catchments provide water for primary production, recreation and sanitation as well as maintaining those natural environments essential for plants and animals (including humans). Poor management practices on land can lead to deterioration in water quality. Poor water quality is damaging to the natural environment, and treating such water to ensure that it is safe is costly and energy consuming. Good water quality depends on us understanding and managing each of the environments in the catchment.
An unfortunate result of our lifestyles and growing populations is a range of environmental problems such as soil erosion, water pollution and loss of native plants and animals. We all contribute to these problems, either directly or indirectly. By using practices not suited to our harsh climate and by managing natural resources separately and independently, we have upset the natural balance of our environment. The quality and quantity of the water we drink, the food we eat and the building products we use, are dependent on the condition of the land and the practices used on that land.
We have created a number of problems, many interrelated, not only for ourselves but for future generations. For example, in the past we disposed of waste thoughtlessly, causing problems now and for the future. Everyone can do something to overcome these problems in their own area.
We all live in a catchment
Catchments are ideal units to work with when looking at land use and management issues because everything is linked by water, and what happens in one part of a catchment area is likely to affect the rest of it. For example, a soil erosion problem, on a farm near the top of a catchment area, may lead to silt and agricultural chemicals ending up in catchment creeks and rivers and eventually making their way out the ocean where they can severely damage coral reefs. Similarly, poor management of effluent discharge from cities and towns can have a devastating effect on water quality.
Approaches to natural resource management
Integrated catchment management and regional natural resource management approaches aim to balance the range of uses of land, water and other natural resources in river catchments, to ensure the future preservation of the environment while maintaining sustainable production. It seeks to bring together a range of people from a catchment or a number of similar catchments that are involved in land use decisions within a catchment. Catchment coordinating committees and regional natural resource management groups include farmers, graziers, conservationists, state and local government representatives, industrialists and other community members.
Students' prior understandings
This section outlines a number of notions that students may have which need to be corrected or developed. A number of activities have been suggested to help teachers to improve students’ understanding of basic concepts.
Students may think that rain comes from the sky or heaven and not necessarily from clouds.
The Water Cycle, A Model Water Cycle and Acting out the Water Cycle activities may enhance the students understanding of how rain is created.
Students may think that clouds are fluffy white cotton balls.
Show the student examples of all types of clouds. Pictures/photos/posters/books/videos may be a source of examples of different types of clouds.
Share student’s experiences of water vapour e.g. fog, a boiling kettle, being in a cloud while on a mountain in wet weather, watching a steam train, windows "fogging" in a car.
Students may be unfamiliar with the concept that water can exist in different states, liquid (water droplets), gas (vapour), solid (ice).
The Model Water Cycle activity will demonstrate water as a solid, liquid and gas.
Students may have difficulty understanding how water from the Earth can become clouds through evaporation and therefore rain.
The image in Resource Sheet 2 - the water cycle can be magnified to create a poster used in may enhance the student’s understanding of the evaporation and condensation process.
Leaving water in a container in the sun until it has evaporated also will help to demonstrate the above.
Students may think that a river is big (wide) and always flowing.
Show the student examples of dry and barely flowing waterways or rivers. Pictures, photos, posters, books or videos may be a source of examples of different types of waterways or rivers.
Students may think that a river could not start in the mountains, as there are no rivers in the mountains only at best little streams.
Show the student a picture of the source of a river. Pictures, photos, posters, books, maps or videos may be a source of examples of different types of waterways or rivers.
Students may not understand how water gets in the clouds (evaporation). They may think this is not possible.
The Water Cycle activity may enhance the student’s understanding of evaporation.
Students may be unaware that snow is a form of precipitation. They may also think it always remains a solid.
Show the student a picture of melting snow. Melting ice could also enhance the student’s understanding that snow melts and doesn’t remain as a solid.
Terms associated with the water cycle, catchment areas, the testing of water quality and environs are essential to the activities in this module. For example:
Students may already be aware of some of this terminology. If so, the activities provide opportunities for them to evaluate current usage.
School authority policies
Teachers need to be aware of and observe school authority policies that may be relevant to this module.
Safety policies are of particular relevance to the activities within this module. It is essential that demonstrations, and student activities are conducted according to procedures developed through appropriate risk assessments at the school.
In this module, teachers need to consider safety issues relating to conducting excursions to field study sites.
Foster, D. 1994, Waterwatch Queensland Technical Manual, Department of Primary Industries, Queensland.
Foster, D., Rob, J. and Yorkston, T. 1995, Waterwatch and Your Catchment, Department of Primary Industries, Queensland.
Lubczenka, V. 1994, Saltwatch Activity Book, Department of Primary Industries, Queensland.
Kelly, K. 1992, Catchment Care Education Kit, Department of Primary Industries, Queensland.
Department of Natural Resources, 1995, Whizzy’s Incredible Journeys (kit), Department of Natural Resources, Queensland
Department of Natural Resources, 1997, Whizzy’s and Zack’s Fabulous Adventures (kit), Department of Natural Resources, Queensland.
Last updated 31 August 2010