ENVIRONMENTAL CHANGE

Merri Creek Self-Guided Field Trip

Aim:

This is an exercise in learning through your own observations of the real world. These are overall questions you should consider during this exercise:

How has the environment along changed over the period of European settlement in and what have been the forces driving those changes?

What do your observations of Merri Creek tell you about people’s attitudes to the environment in which they live?

Logistics:

The field trip starts at Jukes Road, Fawkner (Melway ref 18 A2) and ends at the confluence of Merri Creek and the (Melway ref 44 F3). This route is not accessible by car. The best way to do the trip is by bicycle as there is a good bike path the whole way. You could walk but it will take much longer.

Take the train to Gowrie Station and ride down Juke Road to Merri Creek. At the end of the Path you will be at the Yarra River and close to Park Station.

This exercise is intended to take one day of your time. You should be able to complete the trip and write your report within that time. Specific Issues:

1. At the end of Jukes Road you will enter the Merri Creek Reserve in an area of grassland with some new plantings of native trees. Go straight ahead along a mown pathway which will take you down to the creek. From this point follow the creek downstream.

2. Take note of the land use along the riparian corridor of the creek (ie the land immediately adjacent to the creek) and the land use adjoining this riparian corridor. The riparian corridor will mainly be occupied by parks, undeveloped land with mixtures of exotic and indigenous vegetation, wetlands, sports fields etc and the land which adjoins it will be mainly dominated by residential and commercial land uses. The land use activities along the creek reflect the kinds of values people place on this area. You should consider this when writing your answer for Section 2 of the hand-in material.

3. Where you first join the creek at Jukes Road there is a good exposure of bedrock in the creek bank. Observe and describe this section. You will find it useful to consult the local geology map when answering this question.

4. At the end of McBryde Street a piped drain enters the creek. This is the first of many you will see as you go along the creek. Where does the water in these drains come from?

5. You should note the occurrence of exotic plants along the creek. There are many plants which have escaped from urban gardens and pest species such as blackberries and willows which invade the waterway.

6. At the first bridge across the creek note the slope on the left. How does it differ from the one you described at Jukes Road? How has this slope been formed?

7. Looking downstream from the second bridge across the creek describe signs you can see of the impact of the surrounding urban area on the creek. What evidence is there to tell you how high the water level has been there?

8. The path passes under a footbridge which joins Baker Road and McMahons Road. There are large concrete plinths here painted white. There are access points to the main sewer which has been laid along the alignment of Merri Creek. You will notice that the creek zone has also been used for overhead electricity transmission lines.

9. Also at this point note the large trees in the channel. These are willows, an exotic pest although most of them were deliberately planted in earlier times for “beautification” and to stabilise stream banks. Note also the large cobbles in the stream bed. Flow velocities during floods must be high enough to move particles this size, hence all the flood warnings along the path.

10. Just past Ida Street a tributary enters from the right. Note the rock laid to protect the bank from erosion.

11. There is a metal structure floating in the creek channel just downstream of the Carr Street Bridge. What do you think it is for and why has it been put here by ? 12. Coburg Lake is not a natural lake and just after you pass it you will see the dm wall which forms the lake. The bike path actually goes down the spillway of the dam. This was the site of a basalt quarry and the stone from here was used to build Pentridge Prison which is just across the road from here (though it is no longer used as a prison). What impact do you think this dam has on the movement of fish along the creek?

13. On your journey down the creek, observe how people use this space and how the pattern of use varies along the creek. Obviously the number of people you see will depend on the day of the week and the time of day you visit.

14. There is a lot of litter in the creek channel. What does its nature and distribution tell you about how it got there?

15. Just before you cross the suspension bridge at Kendall Street there is a small market garden. This is the last remaining market garden on the creek and indicates something about changing uses of this area.

16. Note the Strettle Wetland and associated levee bank (the bike path travels along the tope of the artificial levee for a short distance). Why has the wetland and the levee bank been built?

17. Just before you cross the road bridge at Moreland Road there are posts on the bank with black and white stripes and numbers. These indicate water level in the creek and are part of a stream flow measuring station.

18. Attached to these notes is a copy of section of a map compiled by the former Melbourne and Metropolitan Board of Works in the 1890s. It shows the area between the Northcote Golf Course and the Blythe Road Bridge. Describe the land use changes in this area since the map was compiled 100 years ago.

19. You cross the creek on a high bridge at Rushall Station. In the creek directly under the bridge you will see the remains of an artificial channel. Early management of the creek was directed at trying to contain it in a manufactured channel. These channels are prominent in other Melbourne urban creeks.

20. The path ends at the Yarra River. is a natural rock bar across the river at this point but its height has been increased by the construction of a concrete wall. Why?

21. Against the northern bank of the Yarra at Dight Falls there is a set of artificial rapids constructed to provide fish passage past the falls.

22. There is a good bedrock exposure in the bank of the Yarra at Dights Falls. How does this differ from the bedrock you have seen in the banks of Merri Creek? What you must hand in:

1. Answers to the specific questions in issues 3, 4, 6, 7, 11, 12, 14, 16, 18, 20, 22.

2. A brief discussion of the main questions for this exercise (no more than 1500 words).

How has the environment along Merri Creek changed over the period European settlement in Melbourne and what have been the forces driving those changes?

What do your observations of Merri Creek tell you about people’s attitudes to the environment in which they live?

Other resources available to you:

A copy of part of the Melbourne 1:250 000 topographic map sheet and the Melbourne 1:250 000 Geological sheet are displayed on the subject notice board in the old Commerce Building. DO NOT REMOVE THESE MAPS FROM THE NOTICE BOARD. In the Baillieu Library Map Room (located in the ERC Library) you can see the originals of these maps. The Map Room also has maps of this area at scales of 1:100 000 and 1:25 000.

Wigney, Rebecca (Ed.) 1994, Plants of the Merri Merri: a home gardener’s guide to using indigenous plants in the northern suburbs of Melbourne, Merri Creek Management Committee, Northcote, Vic (UniM BioMed 581.99451 MERR).

I.D. Rutherford and L.R. Ducatel, 1994, Impact of urbanisation on natural streams. Water, 21(2), 12-16.

G.P. Codner, 1994, Urban stream water quality. Water, 21(2), 34-35.

(the journal Water is held in the periodical collection of the Engineering Branch Library)

Some Background Information

Urban waterways were among the first casualties of the settlement of Melbourne by Europeans. Within 20 years of establishment of the settlement on the Yarra the river had become so polluted that it was no longer able to be used as a water supply and was distinctly unpleasant to be near. Before the construction of the sewerage system, much domestic and industrial waste water was released into the natural drainage net and creeks like Merri Creek also became polluted and were shunned and avoided by residents. The creeks and their riparian strips became dumping grounds for rubbish and became heavily infested with weeds.

At the same time the establishment of urban infrastructure in the catchments of these creeks produced dramatic changes to their hydrology. The large proportion of impermeable surface in urban areas and the drains designed for efficient removal of excess storm water combine to produce more flashy response to rainfall and flood peaks of any given recurrence interval are larger than those from equivalent non-urban catchments. Flooding became a problem as did bank erosion as the creek channels attempted to adjust their geometry to the changed flow regime. Against this background it is hardly surprising that urban planners tended to favour the creek valleys as corridors for freeways (no one else seemed to want them). In order to reduce flooding and stabilise the channel many creeks were lined with concrete and some even put underground entirely. There is an urban creek underneath Elizabeth Street in the city.

Improvements in urban sanitation and better industrial waste disposal have cleaned up the water quality of urban creeks and this, together with an emerging environmental consciousness within the population generally have helped to change attitudes to urban creeks. They are now more likely to be seen by residents as recreation areas with high amenity value. Melbournians are beginning to reclaim their urban creeks as linear parks but even with the best will in the world they cannot be restored to their natural state. The hydrological changes brought about by urbanisation of the catchments are probably permanent and visitor pressures are becoming very high (higher, in fact, than Bay).

There are, however, many aspects of their use and management which can be greatly improved and Merri Creek, with its strong community support and well organised Management Committee, is probably the best example of urban waterway restoration and management in Melbourne. Achieving this improved management outcome requires much more than a knowledge of the techniques which need to be used. It also requires political skill to ensure that governments at state and local level provide the necessary financial support, put in place appropriate planning and other legislative provisions and administer those planning instruments effectively. Private landholders along the waterways also have an important role to play.