The Natural History of the Ginninderra Catchment - Gaining Insight

A Scoping Report for Members

By Stephen Selden for the Ginninderra Catchment Group

Introduction

As we look around the Ginninderra Catchment today it is often difficult to picture what sort of environment was once here. We have imposed dramatic change on the catchment landscape. Plant and animal communities that were once here have been replaced by a world largely of our own making.

Over large areas native plant communities are gone or left as valuable traces. This is where intense development has not occurred. What we see instead elsewhere is exotic pasture and urbanisation. Exotic grasses have become dominant in agricultural areas as a result of a movement to replace native pastures referred to as “pasture improvement”. This introduction of exotic grasses along with the application of fertilizers was intended to lift production. Many native species have lost out, as these changed conditions do not favour them. The value of native grasses is however coming back to people’s attention as the affects of our management start to tell.

Urbanised areas have changed even more. The legacy of a pastoral past is still present with pasture grasses still dominant over large areas. Other plants that we have introduced include some of our most serious weeds. Crack Willows are a good example. These were once planted on purpose when in a different time it was thought they could be effective in stabilizing stream banks. The willows are mostly gone now but they did disturb the ecology and affected the characteristics of Ginninderra creek for many years. Horticulture has introduced weeds and is one of the most serious sources of introduction. That is people’s own gardens. Other organisms have also been introduced such as weather loaches from aquarium releases or European Wasps. These and other accidental introductions have had a heavy impact.

Natural water flows have also been dramatically altered first by grazing then urbanisation. With rapid urbanisation we have had to deal with problems resulting from the disposal of stormwater into a few creeks and streams within our catchment.

In our role as Landcarers, we can look back at what once was and what has happened to create the environment we are working with now. We will not be able bring about a return to a pristine state and should not aim for this. Rather we can use what we have learned from understanding the changes we have brought and utilize the tools we have to manage the problems we have caused. It so happens that the plants that live here are often our very best tools within this living environment and we can have a positive affect by using them well.

Chapter One

The Ginninderra Catchment – An Overview

This overview of the Ginninderra Catchment makes extensive use of images, the Google Earth Platform and other GIS programs. These are good tools when used well and can serve to assist people in becoming oriented to the catchment landscape. The images below have been generated using a mapping platform and Google Earth. They show the Ginninderra Catchment from varying angles and help provide a real imagery picture.
Note: The Google Earth platform can be used for educational purposes without breaching copyright.

The map above incorporates data that is © Copyright Commonwealth of Australia (Geoscience Australia) 2006

Go to the next section in Our Catchment History – 2. Historic Accounts of the Ginninderra Catchment.

Ginninderra Catchment 1 — The hydrological boundary of the Ginninderra Catchment is shown in blue. The white line (generated using Google Earth) is the border between the ACT and NSW. A large proportion of the Ginninderra Catchment is actually in NSW. Water flowing from NSW joins Ginninderra Creek through Gooromon Ponds Creek. Gooromon Ponds Creek joins Ginninderra Creek not long after it flows out of Macgregor and past part of Dunlop.

Ginn Cment Looking East — This image shows the Ginninderra Catchment looking east. The Murrumbidgee can be seen at the bottom of the screen. Ginninderra Creek flows into the Murrumbidgee at the point where the blue catchment border touches the line of the Murrumbidgee River. Ginninderra Creek leaves the ACT via the (now closed) Ginninderra Falls Park.This image shows the Ginninderra Catchment looking east. The Murrumbidgee can be seen at the bottom of the screen. Ginninderra Creek flows into the Murrumbidgee at the point where the blue catchment border touches the line of the Murrumbidgee River. Ginninderra Creek leaves the ACT via the (now closed) Ginninderra Falls Park.

Ginn Cment Looking North — This image shows the Ginninderra Catchment looking north. The Molonglo River can be seen snaking in the bottom left of the picture. At the top of the slopes above the Molonglo, the Ginninderra Catchment follows a distinct ridge. Part of this ridge is made up of the hills of Aranda Bushland, Mount Painter and The Pinnacle. It goes on all the way over to the Belconnen Golf Coarse. Drake Brokeman Drive follows a lot of this ridge.

Ginn Cment Looking West — This image shows the Ginninderra Catchment looking west. Mulligans Flat is in the foreground just below Gungahlin.

Ginn Cment Looking South — This image shows the Ginninderra Catchment looking south from NSW into the ACT. There is still a lot of farming within the catchment as this image clearly shows. The straight line that can be traced from the “Google” logo in the bottom left hand corner is the Barton Highway.

The Ginninderra Catchment is part of the greater catchment of the Murrumbidgee River. It in turn is part of the Murray Darling Basin the largest river catchment system in Australia. The satellite image above shows the Ginninderra Catchment area and the Murrumbidgee Catchment shown. We are part of a bigger picture.