Environment, Climate Change and Water

Index:

2. Catchments

HSIE Stage 2 Outcomes

The activities associated with this topic meet the following curriculum outcomes:
Patterns of Place and Location ENS 2.5

Geography Stage 5 Outcomes

The activities associated with this topic meet the following syllabus outcomes in focus areas 5A2 and 5A3:

5.3 Selects and uses appropriate written, oral or graphic forms to communicate geographical information
5.4 Demonstrates a sense of place
5.6 Analyes the impacts of different perspective's on geographical issues at local, national and global scales
5.9 Applies geographical knowledge, understanding and skills to demonstrate active and informed citizenship

Science and Technology K-6 Outcomes

The activities associated with this topic contribute to achievement of the following Stage 2 outcomes:
BE S2.1 creates, models and evaluates built environments reflecting consideration of functional and aesthetic factors.
LT S2.3 identifies and describes the structure and function of living things and ways in which living things interact with other living things and their environment.
INV S2.7 conducts investigations by observing, questioning, predicting, testing, collecting, recording and analysing data, and drawing conclusions.

The activities also have links to the following Stage 3 outcomes:
BE S3.1 creates and evaluates built environments demonstrating consideration of sustainability and aesthetic, cultural, safety and functional issues.
LT S3.3 identifies, describes and evaluates the interactions between living things and their effects on the environment.
INV S3.7 conducts their own investigations and makes judgements based on the results of observing, questioning, planning, predicting, testing, collecting, recording and analysing data and drawing conclusions

Background information

Background information compiled from:

Managing Urban Stormwater - Strategic Framework, NSW Environment Protection Authority, 1997.

Urban Total Catchment Management, Kit produced by Urban Catchments Coordinating Committee, 1999.

NSW State of the Environment 1997 and 2000 NSW Environment Protection Authority, 1997 and 2000

What is a Catchment?

A catchment is the land area from which all the water flows to one point. As well as rivers, lakes and creeks, the catchment includes the land contained within its physical boundaries. Everything in a catchment is linked. What happens in one part of a catchment will have an effect downstream. A catchment also includes the stormwater drains and pipes that carry water that runs off roofs, driveways, roads and other impervious surfaces.

NSW River Catchments

The headwaters of most NSW rivers are in the Great Dividing Range, from which they flow east to the Pacific Ocean or west to the Murray-Darling system. The east-flowing streams generally have higher, more reliable flows than those in the west, because of higher precipitation on the eastern slopes. NSW coastal rivers discharge almost three times the amount of water than do rivers flowing inland. Average coastal river discharge is 28 million megalitres per year. Average inland river discharge is 10.5 million megalitres per year.

River Systems

Rivers may be large or small, but they all follow the same rules of drainage. Rivers may begin from underground water coming to the surface (springs), from rainfall, from snowmelt or drainage from a wetland or a lake. Some creeks dry up during periods of low rainfall. These are called intermittent streams.

As creeks increase in flow and join with other creeks, a branching network is established. This network from headwater streams to the river mouth is called a river system. A catchment is made up of smaller sub-catchments that feed into the river system.

Impact of Urbanisation

Urbanisation increases the area of impervious surfaces (such as roads and roofs) in a catchment. This causes rainfall that previously infiltrated into soil or flowed off catchments at a slow rate, to flow off the catchment quickly and in greater volumes.

In urban areas, many small creeks have been replaced with piped and lined drainage systems. This accelerates the rate at which stormwater is carried and increases flooding and erosion problems. The concentration of pollutants such as oil, grease, sediment and organic matter running off urban surfaces causes deterioration in the water quality downstream.