January 12, 2025 • 43 mins
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In this episode, we’re diving into the waters of the Mary River with environmental engineer Misko Ivezich. With over 15 years of experience at Alluvium, Misko has long been at the forefront of combating river erosion and sediment issues which are crucial to the health of riparian ecosystems and downstream systems which receive their flow. Today, we’re focusing on a successful project on the Mary River, a vital waterway that flows through Queensland and plays a pivotal role in the health of the Great Barrier Reef.
The project, led by Misko, implemented new engineering solutions and extensive revegetation to reduce bank erosion by an impressive 85% during the 2022 floods, compared to past data. This story isn’t just about geological and riparian engineering; it’s about ecological recovery. These efforts have had a substantial impact on native species like the Mary River Turtle and Lungfish, whose habitats are crucial for their survival yet have been degraded over time. Through this project, we see a blend of science, policy, and community engagement coming together to foster a more stable and vibrant ecosystem.
Join us as Misko walks us through this landmark initiative, shedding light on how strategic environmental management can lead to sustainable outcomes for both our natural heritage and the communities of wildlife and people who depend on it.
This episode talks about:
• Overview of the Mary River's importance and challenges
• Discussion on river erosion and past flood impacts
• Importance of vegetation in stabilising riverbanks
• Addressing sediment loads impacting the Great Barrier Reef
• Success of community initiatives in river management
• Engineering strategies used in the restoration project
• Future plans and ongoing work for the Mary River
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Episode Transcript
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Hello and welcome to Take Me tothe River where we share
stories and inspire hope withextraordinary people who care
(01:27):
for our rivers.
I'm your host, Dr Shu-AnneLovett.
In this episode, we're divinginto the waters of the Mary
River in Queensland withenvironmental engineer Mishko
Ivozic.
Mishko has been at theforefront of combating river
erosion and sediment issues,which are crucial to the health
of riparian ecosystems and thedownstream rivers that receive
(01:49):
their flow.
Today, we're focusing on aproject Mishko has been working
on on the Mary River.
The Mary River is particularlyimportant because its flows go
out onto the Great Barrier Reefand it has been the source of
significant sediment loads goingout to this very precious
ecosystem.
This project implemented newengineering solutions and
(02:09):
extensive revegetation to reducebank erosion during the 2022
floods.
This story isn't just aboutgeological and riparian
engineering.
It's about ecological recoveryfor threatened species Mary
River Turtle and the Mary RiverCod but it's also about a
community recovering from theimpacts of drastic flooding that
(02:29):
saw their river literallywashed away before their very
eyes.
Join me now as Mishko takes usthrough this incredible
initiative.
Well welcome, Mishko.
It's wonderful to have youjoining us today to talk about a
river that I really love andhaven't been to for quite some
time the Mary River up inQueensland.
Can you tell me a bit about howyou've come to know this river
(02:50):
and why you're interested inrivers?
Misko (02:53):
I'll go back to my interest in rivers first before
I get to the Mary River.
So I'm an environmentalengineer, mainly work in river
management, so around riverprocesses and river river
rehabilitation.
I've been doing that for about15 years, currently based in
northern New South Wales, but mywork is all up and down the
east coast and a little bitoverseas.
So how I've got into this work,I guess I sort of fell into it
(03:18):
in many ways.
Obviously I love rivers andI've spent my childhood playing
in creeks and streams and theNorth Island, new Zealand and
the base of the Mount LoftyRanges in Adelaide.
But I never really imagined youcould make a career out of it
playing in creeks.
But I have managed to.
So yeah, so I basically got toit by studying environmental
(03:39):
engineering at AdelaideUniversity but again I didn't
really know where I was going togo with that degree.
I mainly chose it because I wasgood at mathematics and I cared
about the environment and thenatural world.
Finished that degree and stilldidn't really know where I was
going to go with my work, Istarted a PhD for one year at
Adelaide Uni and that was insort of urban stormwater
(03:59):
management and again didn'treally enjoy that probably
didn't have the maturity to do aPhD in my sort of early 20s.
I applied for jobs in Melbourne,had a friend moving to
Melbourne, applied for jobs andgot a job at Alluvium Consulting
, which was a just a freshly newenvironmental consultant, new
specialist specialized in riverrehabilitation work, so went
(04:20):
over there and I guess, yeah,those first formative years at
Alluvium really developed myinterest in rivers and river
processes and riverrehabilitation, and so how I got
to the Mary River was we'redoing quite a lot of work from
Melbourne in southeastQueensland after the floods that
hit that area in 2011, and so Irelocated up to southeast
(04:41):
Queensland at that time to helpwith all those flood recovery
programs.
And again there was anotherflood in 2013.
And, yeah, I went out to theMary River one day.
I was introduced to thisamazing river system, which I've
now been working on for wellover 10 years.
Siwan (04:59):
I love the fact that you say that you know you were
studying and had no idea whereyou were going to end up,
because I was exactly the same.
I did not expect to be runninga river restoration centre at
all.
There's something about rivers,though.
They just get to you and havingthe opportunity to work with
them and the people that lovethem is fantastic.
I was chatting to Mishkoearlier because I actually
(05:22):
remember the Mary River from mytime in Land and Water Australia
, which is now 20 years ago, andwe had some great projects on
the Mary River, with somefarmers who were fencing off
their stock and doingregeneration work.
Tell me about a site that weactually worked on that now
you've actually gone and workedon, where we'd actually put some
structures into the river totry and control sediment.
Misko (05:46):
Yeah, so this is a site up between Kennedale and not
between Kenilworth and Connedale, and you put in some structures
in the late 90s with BradWedlock from the Mary River
Catchment Coordination Committee, who I still work with very
closely, and so that was aboutputting in some structures along
the toe to protect the bank toefrom erosion and then
revegetating the upper bank, andit's largely been intact over
(06:08):
sort of 20 years later.
But the middle of the sectionhas become quite badly eroded in
recent flood events and so werecently went in there as part
of some funding for protectionof the Great Barrier Reef and
the Great Barrier ReefFoundation and rehabilitated
sort of 200 metre section withinthe middle of that project area
to mainly protect therevegetation works downstream
(06:28):
that were planted in the late90s that are doing really,
really well.
So you know really mature treesnow.
So it's great to see.
Siwan (06:35):
It's a wonderful part of the world because the trees
actually grow quite quicklythere.
We had a project in the MaryRiver and then we went to look
at one in Tasmania and thosetrees were still very little.
Misko (06:47):
So it's great.
You're very right.
Siwan (06:49):
It's a very sort of lucky sweet spot on the east coast of
Australia nice, warmtemperature, lots of rays, and
things grow remarkably quicklythey do indeed, so tell me a bit
more about erosion for some ofour listeners who might not
understand what that actuallymeans for a river in terms of
sediment, and particularly whatcan happen with floods in
(07:10):
systems like this.
So you mentioned, in 2013 therewas another big flood in the
Mary River.
What happened to the river as aresult of that flooding?
Misko (07:19):
Erosion is an essential process in river systems to
start with.
So we often think of erosion asa really really bad thing and
something that needs to bemanaged, but it's a very natural
process and it's fundamental toa lot of the landscapes we see
within our catchments All thehills and floodplains and
everything that's formed fromeither erosion or deposition
over sort of thousands of years,and so an alluvial river is
(07:41):
constantly eroding anddepositing sediment and that
helps form floodplains.
It's really really importantfor agriculture and growing food
.
For us.
It helps scour out pools whichare really important for
maintaining our native fishcommunities and our more broader
fisheries as well.
But often when we, you know,change something within our
catchments and river systems, wecan sort of change those
(08:03):
erosion and deposition processesand sort of mess.
They're sort of in this finebalance, if you like, and if we
mess with things in thecatchment or the riparian zone,
we can tip the balance eitherinto a really erosional phase
where you get really much moreerosion, or a depositional phase
where the channel just fills upwith sands and cobbles and
gravels, and so I'll give it agive you.
One example is the removal ofriparian vegetation.
(08:25):
So vegetation helps stabiliseriverbanks and provide hydraulic
roughness that basically slowsdown velocity and flow up
against the riverbank.
And when we remove thatvegetation from the riverbanks
there's nothing to take up thatexcess flood energy or stream
power and we start to seeerosion of our channels and
widening of the channel, causingloss of floodplains and loss of
(08:48):
those really deep pools thatare so critical for our
in-stream biota.
And I guess another one in theMary River which has caused a
whole lot of issue has been sandand gravel extraction.
So the Mary River was basicallya sand and gravel mine for the
latter part of the 20th century.
Literally hundreds of thousandsof cubic metres of sand and
gravel mine for the latter partof the 20th century and
(09:08):
literally hundreds of thousandsof cubic meters of sand and
gravel were taken out of theriver to support the
urbanization of the sunshinecoast.
And what that does is itdestabilizes the riverbed and it
steepens up the bed profile,leading to an increased slope
and faster velocities and morestream power.
And again, when you get thosebig flood events, water travels
a lot more faster.
Particularly once you govegetation on the banks, you get
really high rates events.
Water travels a lot more fast.
Particularly once you've gotvegetation on the banks, you get
really high rates of channelerosion and channel widening and
(09:29):
a loss of all those reallyimportant habitat features, like
our floodplains and our pools,that are really important for,
yeah, ecological communities aswell as our agricultural
communities as well.
Siwan (09:40):
And I think it's one of those things that you know
humans, we like to fix stuff,and so when we think about
floods, for some people it'sreally a license to get the
water away as quickly aspossible, but that actually then
means that the water createsmore damage because it's not
allowed to slow down and go at alot less speed and a lot less
(10:03):
destructive power when youactually allow it to disperse
more.
So with a catchment like theMary River, so the gravel and
sands has been reduced, it'sstill got sediment coming in,
and then it gets this whack ofwater coming through.
What happened to the river?
Like did it?
Were there big chunks of thebed falling in, or was it just
(10:26):
filled up with sand?
How did it look after thatflood?
That caused people to actuallysay, okay, we've got to do some
more work here.
Misko (10:34):
Yes, the main reach, which we've focused our recent
sort of work on, is around theKenilworth area, but since then
we've obviously been workingacross the whole Mary River as
well, but I'll just describe thechanges around that Kenilworth
reach where we did our originalplan and the majority of our
work.
So what we can gather from youknow, historical information of
the channel, so old surveys thatwere done in the 1950s, and
(10:57):
historical area imagery is thatthe channel bed's lowered by
about two metres, from what wecan tell, since the 1950s, and
its channel width has probablydoubled or in some cases tripled
in width.
So it might have gone from 40 or50 metres wide to well over 100
metres wide in some sections,and the bed's lowered a couple
of metres as well.
So when I went out there afterthe I'm happy to put up some
(11:19):
photos as well when I went outthere after the sort of 2013
flood event, it was just, youknow, sheer vertical cliffs of
10 metres high of loamy, highlyerodible sediments just
collapsing into really turbidwater with high sediment loads
working its way through it, andobviously it's lost all those
really important in-streamhabitat features, like the pools
(11:40):
, which supports a prettyendangered species in the Mary,
like the Mary River Cod and theMary River Turtle, and so it's
basically a basket case.
After that 2013 flood, it wasone of the most degraded rivers
in Australia.
I think it had been called atsome stage in the late 20th
century and at that time it wasjust when the Great Barrier Reef
was coming into focus as a keysort of issue, and it was
probably one of the mostunstable river reaches within
(12:02):
the Great Barrier Reef marinepark catchment areas.
Siwan (12:06):
So a pretty sad and sorry state.
And, listeners, we will putsome photos up so that you can
see that poor old river afterthe flooding.
The connection with the reef Ithink there has been a growing
awareness about the fact that'swhat comes through our estuaries
.
Now onto the reef.
You know people have seenphotographs of plumes, but how
(12:29):
much sediment are we actuallytalking about here, like, does
it really make a huge differenceto the reef?
What's your view on this?
Misko (12:37):
Well, it's different, for every catchment where the
sediment loads are coming from,from the Mary River catchment,
the main source to that area ofthe lower, the southern portion
of the Great Barrier Reef.
It's a very southern catchmentwith the Great Barrier Reef
Marine Park Lagoon and it's yeah, the stream bank erosion has
been estimated to be.
You know, close to half of thefine sediment load getting out
(12:57):
to the reef is coming fromchannel erosion within the Mary
River catchment.
Siwan (13:01):
Wow, that's an enormous amount.
Yeah, so that explains havingsome support from the Great
Barrier Reef.
Was it the conservation fundyou were talking about?
I can't remember the exact name.
Misko (13:12):
Great Barrier Reef Foundation.
Yeah, they invested as apriority.
I couldn't tell you the exactload off the top of my head, but
it's probably tens of thousandsof tonnes every year of fine
sediment coming out the MaryRiver.
Siwan (13:23):
And so when you're talking fine sediment, is that
like tiny granules of sand, likejust for people to have an idea
about what you're meaning byfine?
No, it's even tinier than sand.
Misko (13:35):
It's the clay fraction, so there's clay silt and then
sand as a sort of sedimentclasses.
So it's a really, really finestuff that stays in suspension.
It doesn't really settle outwithin river systems very easily
and is transported insuspension out into the ocean
environment and then eventuallysettles in the ocean environment
and in particular for the MaryRiver, it goes out in the Great
(13:58):
Sandy Strait, which is near Garyor Fraser Island, and so all
that fine clay particles sort ofsettle down in that area and
they're famous for theirseagrass beds and their dugong
sort of areas and all that finesediment smothers those
ecosystems.
Yeah, so when you get theerosion you also get the sand
(14:19):
particles as well, but theygenerally get deposited out in
the river network and they don'tmake it out to the ocean
environment.
Siwan (14:25):
Oh, that's interesting.
So you actually get a range ofsediment that the river's
carrying, but it sort of dropsoff the bigger particles before
it gets right out.
I didn't know that.
So when we see those big plumes, it's that fine suspended stuff
that we're often seeing.
Misko (14:41):
Exactly the coarse stuff still has an impact,
particularly on the river system.
So the sands and gravels andthe coarser things are more
readily visible when you're outlooking at rivers.
That fills up pools and hasimpacts on in-stream habitat
diversity, but it's the fine,really fine clay fractions
that's more important for themanagement of marine
(15:04):
environments.
Siwan (15:05):
So, when it came to designing something to address
this erosion in the Mary River,do you take the sediment profile
into account?
Does that impact on the sort ofdesign that you might develop?
Misko (15:23):
Yeah, definitely.
So you're considering sedimentbeing moved through the river,
on the bed of the channel, butalso the sediment within the
banks, and what sort of profilesneeded to stabilise the
vegetation, and then sort ofsurface treatments as well as
particularly sandy materials.
All that stuff definitely needsto be considered.
Siwan (15:36):
So let's talk specifics then.
What did you actually do withthis project of yours on the
Mary River?
Misko (15:42):
Okay, I'll go back to right at the start.
So you know, I went out thereafter the 2013 flood event and
primarily with Brad Wedlock fromthe Mary River Catchment
Coordination Committee.
As I said, it just looked likean absolute basket case really
of a river and probably at thattime probably didn't ever think
you were ever going to be ableto do anything to address the
(16:02):
issues that you're seeing inthat river.
That's how extreme the problemsseemed.
However, we thought I said weneed to come up with some sort
of plan.
So we got together all the keystakeholders that had an
interest in the river, soBurnett, mary Regional Group,
another regional group workingin catchment management in the
area, sq Water, who's a localwater authority who supplies
(16:22):
water to the township ofKenilworth, and Sunshine Coast
Regional Council, which is thelocal government.
We all got together and we saidlet's come up with a plan for
this particular stretch of river, and I guess the key objective
was to try to increase theresistance of the river so it
would be able to withstand tothe floods of a similar
magnitude that occurred in 2013.
So in that flood event, some ofthe banks migrated over 50
(16:46):
metres, taking out massive areasof really great agricultural
floodplain land and just washingit down the river and out to
the reef the reef.
But there are also some otherobviously ecological outcomes we
wanted to get so by gettingincreased vegetation on the
banks and, over time, returningsome of that in-stream habitat
diversity that supports thosethreatened species I mentioned
(17:07):
earlier.
Siwan (17:08):
It must have been absolutely devastating for the
local community to see thathappen to their river, because I
just know from my working inthe 1990s there there was so
much being done to try and savethe Mary River Turtle and the
Mary River Cod.
So, yeah, you must have beendealing with a highly
traumatized community.
(17:28):
Is that what it felt like toyou?
Misko (17:30):
Yeah, yeah, definitely, and the Mary River Cattle
Conservation Committee arereally great in that aspect of
you know, talking to landholdersand sympathising with them and
building those long-termrelationships.
But, yeah, after thatparticular flood but all flood
events, you get reallytraumatised communities when
they see such drastic change,the changes in the river and
(17:51):
their land as well.
Siwan (17:54):
So, yeah, continue on.
I'm fascinated.
It just struck me that, wow,that must like 50-metre
migration, that is a lot of landto see disappear before you,
and 10-metre high banks as well.
Misko (18:07):
Oh wow, 50 metres by 10, the amount of material that's
coming out is huge.
Yes, we came up with a plan.
So obviously the key goal waswe wanted to get really good
native riparian vegetationgrowing on the banks and in the
channel and on the floodplainagain, and that's going to
provide the long term resistanceto erosion but also all the
other ecological benefits wewant as well.
(18:28):
We have some problems or someareas where the banks were
vertical and 10 metres high andsome of the flood velocities on
those outside bend areas werereally really high.
So planting trees wasn't goingto be feasible by itself.
So we had to come up with someother approaches to support the
revegetation works.
And that's when we look at sortof soft engineering approaches
(18:50):
reshaping banks and putting inlogs or pile structures along
the tow to slow down thevelocity.
So as an engineer working inrivers, I guess my philosophy is
always just trying to do theminimum amount of engineering
that's required to supportvegetation to get established.
So you want the vegetation todo all the work and be the
long-term mechanism that holdsour river channels together.
(19:10):
But you need a little bit ofengineering sometimes to help it
along the way, but not not toomuch.
We're going to be rock lightingriverbanks or over engineering
systems, um, when they don'tneed to.
So a lot of its analysis islooking at the flood, hydraulics
and the geotechnical propertiesand coming up with just the
minimum amount that you'recomfortable with putting in the
system just to help hold ittogether and for the first five
(19:32):
to ten years to allow the timefor the vegetation to get
established.
So with this particular systemwe identified areas where the
velocities were too high or thebanks were too steep and we came
up with some approaches toreprofile the banks back to a
more stable gradient, sort ofone is to three, to allow access
, to revegetate those banks.
And then we installed sort oftimber piles along the tow and
(19:53):
those timber piles act like anartificial forest for the first
five to ten years and slow downthe velocities up against the
toe of the bank and allowsediment and seeds to drop out
in that area as well andregenerate that lower bank zone.
And it just provides enoughresistance in that critical area
for the first sort of 10 to 15years, which then allows the
(20:14):
vegetation to establish on theupper bank and at that point it
doesn't really matter if thetimber piles rot away because
we've got enough vegetation androughness and root reinforcement
in the lower bank, it can helpresist those really big flood
flows and return to more naturalrates of erosion.
We'll still see that erosionand loss of some tree material
(20:34):
that will go into the river andprovide habitat, but it's
nothing like the extreme erosionwe saw in the 2013 flood event,
where some of these banks weremigrating 50 metres.
Siwan (20:46):
So why do you choose to work at the toe of the bank
rather than just focusing on thetop?
Misko (20:53):
The highest forces in a river are down close to the bed
of the river.
So if you've got a big floodflow going, this reach is
greater than 10 metres deep andso the greatest force is right
at the base.
And the greatest force in thebank is obviously at the base of
the river or the bed of theriver up against the toe of the
bank, and that's where you getthe maximum force exerted on the
(21:13):
bank and that causes what iscalled bank toe erosion or
fluvial scour along the toe, andwhat that can do is that
steepens up the bank profileover time until it gets to a
critical point and then it hasgravitational failure.
It comes down to what's calledbank slumping.
So a toe erosion or scour fromthe velocity high velocities of
(21:33):
the toe steepens up the bank andthen you get slumping of the
upper bank material.
So a key thing to stop thatprocess is to provide enough
resistance at the toe.
Toe steepens up the bank andthen you get slumping of the
upper bank material.
So key thing to stop thatprocess is to provide enough
resistance at the toe, where theforces are highest, and then
that will protect the stabilityof the upper bank area where the
actual flood forces are less inthe upper bank and the erosion
there is generally due to thatgravitational mass failure or
(21:55):
bank slumping process.
Siwan (21:58):
It's really interesting, isn't it?
Because, yeah, we focus on thetoe of the bank when we're out
working with farmers as well,but I've certainly been on
stretches of river where you'vegot a really steep bank and
there's one tree just hanging onfor dear life and the farmer
will say that tree's what'scausing that erosion.
You know it's causing the wholething to fall in, and I'm going
(22:19):
that tree is the only thingthat's keeping it up.
Can you explain a bit moreabout that, because it's
counterintuitive for people.
They see a big tree and theythink, oh, that's going to fall
in and pull the bank in with it,but in actual fact, that tree
and its root system is holdingit together.
Misko (22:35):
Yeah, you're right, and it's all the other area around
the tree that's eroded.
It's left that tree standing byitself and the reason that tree
hasn't been able to hold all thebank together is because one
tree can't do all the heavylifting.
You need an army, I guess, isone way of looking at it.
So you need lots of trees andshrubs and ground covers help
holding the bank together, andeach of those three things I
(22:58):
mentioned the ground covers,shrubs and trees do something
slightly different in terms oferosion control.
So your grasses and your groundcovers lay flat and help armour
the underlying alluvialsediments from erosion, provides
a sort of filter layer, if youlike.
So that takes all thehigh-velocity flow force on the
foliage of the grass and theground cover, protecting the
erodible sandy or clay materialunderneath your shrubs, which
(23:22):
have lots of branches andphysical elements.
And physical elements arehighly sort of malleable to move
and get knocked around in floodevents and what that provides
is a lot of frictionalresistance or hydraulic
roughness helps slow down thevelocity, just because the sheer
surface area of all theirlittle small branches and bits
of foliage and then your really,really big trees might not have
(23:42):
a huge impact on the floodvelocities because it's just a
trunk, but it's their rootsystem, is what's happening
underground, and those deeproots and it's almost like
they're providing thereinforcement in the bank prover
like almost like steel andconcrete reinforcement.
Those root systems provide thatreally strong tensile strength
and reduce that mass failure orslumping process I talked about
earlier.
Siwan (24:04):
Yeah, it's a classic one, because you've also got to stop
yourself from saying you'rewrong, because you kind of need
to.
Well, my approach, anyway, isto ask questions about why they
might think that and wherethey've you know.
So you actually are not sayingyou're wrong.
It's more about saying, well,actually, research is showing
this or this or this, so, yeah,it's a better way to go.
(24:26):
In fact, I do remember veryclearly thinking about the
sediment.
I was up on a sugar farm inInnisfail and I was being taken
out to this farm because the guyI was going to see, a guy
called Tom, was known to be avery good riparian manager, and
he took us down to his riparianzone and he had all these
(24:47):
individual trees beautifullypaced apart.
He was mowing around all ofthem, so it all looked very it
was like a garden, and I thought, okay, so that's interesting,
that's the interpretation ofwhat a healthy riparian zone
looks like.
And I left behind him amagazine that I used to produce
at the time called Rip Rap, andit had a whole article on
(25:10):
needing at least a fivecentimetre high swathe of grass
to actually capture sediment.
And so the next day I went backand he went.
So, shu-anuan, I read thatriprap article.
Are you saying that I need tostop mowing as?
much I said yes, I am, but itwas a much better way of going
about it.
And we also then had thediscussion about you actually
(25:32):
need grasses and you need shrubsand you need trees, and it's
that idea that somehow that'sgoing to look messy and it's not
going to actually do as well.
Did you have any resistance inthe community to your approach
to this type of erosion control,or were they sort of fairly
used to that idea?
(25:53):
Did they want more?
Did they want concrete?
Was that going to make themfeel safer?
Misko (25:57):
Every landhold is a little bit different, but I
think at this stage we'll betalking about this project of
the mary river.
At that stage, um, yeah, therewas a lot of uncertainty, I
guess, um skepticism even, but Iguess they had to try something
because they'd seen whathappened from doing nothing.
But moving forward now andseeing the outcome of the, you
know there's been a massivechange in the community and
(26:17):
everyone wants more of this typeof approach and, yeah, I've
convinced many people of thebenefits of this type of work
and the benefits of vegetationmore generally within the
riparian zone.
Siwan (26:28):
Oh, that's great, because I have had people say we just
need green concrete.
That's the environmentalalternative is to go green
concrete.
So let's fast forward then to2022.
There were big floods down theMary River again and I know that
you've recently presented somework to show how your approach
has actually managed towithstand that flooding.
(26:49):
What were you particularlypleased about in terms of how
the river was looking post the22 floods?
Misko (26:56):
I might just go back a bit there in time, if you don't
mind.
Just before what happenedbefore the flood event.
Because, yeah, so we developedup the plan At the time, we
never thought the plan would getfunded.
So that was probably the.
Quite often as consultants, youget paid to develop up plans
and they sit on shelves waitingfor funding and they never get
funded.
So, given the scale of worksthat were required within this
(27:18):
reach, we probably didn't thinkyou know what we were
recommending would ever getfunded.
But then the first funder wasSEQ Water, who their water
offtake for the town was goingto be taken out in the next
flood event if they didn't dosomething to the bank upstream,
the section of bank justupstream of that bank.
So they funded the firstproject and we did that about
(27:38):
2015, which was a major bankreshaping project and
installation of pile fields, asI talked about.
Sunshine Coast Council got theparts of the plan and they
didn't want to really invest inthe engineering or the civil
part of works.
But they jumped at, you know,just going out and fencing and
revegetating all the lower riskareas where the bank was, you
know, more gently sloping anddidn't really need any
(28:00):
engineering or reshaping work.
So they just went to those sortof areas and engaged with
landholders and implemented thefencing and did the planting
works and, as I said, this was atime when the Great Barrier
Reef funding was really sort ofcome online as well, and so, you
know, about five years ago, wegot funding for all the other
really eroding, steeper areasthat needed massive earthworks
(28:21):
and engineering works to supportthe revegetation.
So, slowly but surely, a wholelot of different funders came on
board.
So there was the Queenslandgovernment, there was the
federal government, so,basically, this plan was funded
for a whole range of differentstakeholders over a series of
years, for a whole range ofdifferent stakeholders over a
series of years.
Obviously, most of the work wasimplemented just before the
2022 flood events which camethrough the system.
Siwan (28:46):
That's a great great approach, though, because you
had one plan and one vision, andthen people could say, well,
actually, I'll do this bit, I'lldo this.
So were you sort of theconstant in that, in terms of
being the group to which peoplelook to, to know, okay, if I do
this bit, it's going to work orit's going to fit in with other
(29:06):
stuff that's going on?
Misko (29:07):
with the other stuff that's going on.
So quite early on in theprocess we formed a consortium
between myself and Alluvium, whoI work for, and the Mary of a
Catchment Coordination Committeeand the Burnett Mary Regional
Group or BMLG, and so we formeda consortium and basically we
catch up, you know, everyfortnight or so, and we talk
(29:28):
about the current projects andwe talk about upcoming funding
opportunities we could leverageto invest in the Mary River
catchment.
And so that plan was, you know,a key piece of that exercise to
look for funding opportunities.
And when you're applying forgrants and you've already got a
fully-fledged plan, you're readyto go on some other projects
that have been successful.
It's, you know, looked on muchmore favourably by people um
(29:50):
handing out money for this typeof work makes a huge difference.
Siwan (29:55):
And it also helps, I think, when people move on, if
you still have a plan that a newperson coming in can refer to
or get locked into a newinitiative.
But I know there's so muchgreat work being done around
australia and then when onecrucial, crucial person leaves,
it just falls over and thenyou've got that rebuilding
process.
So I'm delighted to hear that,because I do care about the Mary
(30:15):
River, as I do all rivers, ofcourse.
What about ecological surveys?
You know, my big thing aboutthe Mary River turtle, of course
, is it's a bottom-breathingturtle, so it's got a cloaca.
If no one has seen or heardthat word before, you might not
want to see it.
But yeah, I always think aboutthe bottom breathing turtle,
which is the Mary River.
(30:35):
So what have you learned fromthe ecology?
Misko (30:39):
With ecological surveys.
A big part of what we need todo is part of this work.
So I don't necessarily dealwith that directly, but Mary
River Catchment CoordinationCommittee they're really on top
of doing those surveys before wedo works and while we're doing
works as well.
Because quite often whathappens when we are reshaping or
reprofiling these banks?
The Mary River Turtle lovesnice sandy nesting environments
(31:00):
so we turn a vertical cliffthat's no good for Mary River
Turtle habitat into a nicereprofiled sandy bank and they
sort of run for it and want todo all their nesting there.
But unfortunately we're alsotrying to install piles and do
other things.
So it's quite often during thatearly construction phase we've
got to put up exclusion fencesfor that month or so just to try
(31:21):
and stop them getting onto thebank, to enable us to finish the
works and do the planting andthen they can go for it.
After that they can create abit of a turtle sanctuary for
them.
With this nice, gently slopingbank they can climb up nice and
easily compared to the verticalbank.
So it does take a few headachesduring construction trying to
manage those turtles trying toget up onto these banks and
trying to limit their accesswhile we can.
(31:42):
But yeah, over time we'reimproving their habitat,
providing those more gentlysloped banks that accumulate
sediment and sand, which theylike for their nesting.
Siwan (31:51):
It's almost like you know you've got one of those
billboards coming soon.
You know like don't try now, interms of real estate in the
river, this is going to be thepremier estate, but you have to
make us build it first.
And what about the cod?
Because the cod needs deepholes.
Some of these structures thatyou're putting in not only would
(32:12):
be holding back sediment ormaking it more structurally
sound, but is it also enablingsome scouring to get back a bit
more of those deeper pools thatfish like yeah, it's a bit of a
slower process for the cod.
Misko (32:24):
Because the Mary River has got so wide over several
decades it's lost the ability tomaintain those deeper pools.
And basically how a river scoursout and maintains pools it has
to have a lot of roughness onthe banks.
You imagine really densityvegetated river banks.
It forces flood flows betweenthe vegetation and that helps
scour out the bed and maintainthose pool environments.
(32:44):
And as the river gets wider andwider you don't have
necessarily the force within thebed of the channel to scour out
those pools and maintain thosedeep areas.
So unfortunately a lot of theMary River is a very shallow
river now and a lot of thosedeeper pool areas where the cod
still remains are in thetributaries.
So over time as the vegetationestablishes on the banks and
(33:05):
encroaches more and more in thechannel and on the bars,
hopefully over time you knowthat's probably going to be
decade timescales we can getenough roughness in the channel
back again that we can start toscour out an insect low flow
channel a bit more and providethat bed diversity and habitat
for the cod.
But it's a bit slower process.
It's going to take decadesunfortunately to undo all the
(33:28):
damage that's been done to beddiversity in the Mary River.
Siwan (33:36):
Yeah.
I think, though, that really,if we think, decades is a long
time, it's not actually thatlong in the life of a river.
So I've been doing some workwith traditional owners, who
have a 100 year plan for aparticular river, and I'm
thinking that's actually muchmore sensible, because we do
place a lot of pressure onourselves to get things done
quickly, but nature does respondmore slowly, but probably with
a longer term view in terms ofit being there for much longer
(33:59):
than we're around.
I'm interested with the 2022floods.
What happened in terms of theamount of sediment that was
moving, and were you able to,you know, report back to the
Great Barrier Reef Foundationthat you'd actually managed to
stop some sediment getting outonto the reef?
Misko (34:18):
So 2022 was a wet year across the east coast.
We had a series of smallerfloods in the Mary River, which
culminated in the biggest floodin sort of May 2022.
And so this through the REACHwe worked on, I think.
The flood peak was well over 10to 12 metres high and it was
basically the biggest flood thathad occurred in the system
since the 1990s, so well over 30years.
(34:39):
It's much bigger than the eventin 2013, which instigated all
these projects, and so I thinkthe flood event occurred over a
weekend, so it was a nervousweekend for myself.
I was checking BOM constantly onmy phone and looking at river
heights and rainfall andmonitoring all the gauges and
imagining all these structuresand things that I'd put in the
(35:00):
riverbed that were now 12 metresunderwater and imagining what
was happening to them and howthe sediment was moving through
them.
But I was pretty nervousbecause obviously we'd
implemented millions of dollars'worth of rehabilitation works
in just the years before thisflood event.
So obviously you're reallyquite nervous.
What's happened to all thatinvestment and hundreds of hours
of hard work that you've putinto it?
(35:21):
And so I didn't get out therefor a few weeks, but the few
days after the flood, um Bradfrom MRCCC, um his colleagues,
colleagues did a walk down thereach and I remember being at
work he was sending me textmessages and photos of each
section to see how it stood up.
Suspense was killing me as hewalked around every bend to see
(35:42):
what we were going to see.
But as the photos kept coming in, I just got a bigger smile on
my face because everythinglooked great and the trees were
still there.
They were banged around a bit,but they were largely intact,
and some of these banks that hadmigrated 50 metres nearly 10
years earlier were basicallylargely intact, with very little
deposition.
And then he kept sending methese photos of his gumboots
(36:02):
sinking into all the silt thathad been captured on the banks
as well.
So not only had we stoppederosion on the banks, but all
the vegetation and roughness wewere adding was capturing sands
and silts on the bank as well,so they were basically
accumulating sediment.
So what had been really bigsediment sources were now
becoming these sedimentaccumulation zones and capturing
sediment on the banks.
So everything held up reallyreally well.
It was managed to get out thereand since then we've done a
(36:24):
whole lot of more quantitativeanalysis and collected LiDAR
data of the reach and comparedthe change in the bank
morphology before and after theflood.
And so yeah, we estimate, youknow, sort of effectiveness of
the works is, you know, in therange of sort of 80 to 90%
sediment reductions going fromthe reach and out to the Great
Barrier Reef.
So really really highlyeffective projects at stopping
(36:48):
sediment getting out to the reef.
Siwan (36:50):
That's incredible.
What sort of?
Have you got any idea of sortof tonnes that might mean more
to our listeners?
I mean, the percentages aresuper impressive.
Yeah, so from this, particularbreach.
Misko (37:03):
This is about a sort of four kilometre sort of breach we
primarily did this analysis on.
We're sort of basicallystopping 20,000 cubic metres of
sediment in total each year onaverage and going out to the
reef.
That's, you know, assumingabout half of that's fine
sediment that gets out to sortof the reef environment, so sort
of 10,000 cubic metres.
So that's close to almost, youknow, 15 to 20,000 tonnes of
(37:25):
fine sediment going out to thereef each year.
That we've managed to stop fromthese works.
That's sensational, that's sogood.
I can just imagine you, youknow, seeing gumboot photos and
smiling more and more and peoplegoing.
Siwan (37:40):
Why are you excited about a gumboot in?
Misko (37:42):
sediment River engineers get excited about strange things
.
Siwan (37:46):
They do indeed, they do indeed.
So what are you doing in termsof ongoing work with the Mary
River?
You said you've formed thisconsortium, so you're obviously
still talking.
So what are the plans for theMary River going forward?
Misko (38:00):
Yeah, we're still talking and it's a big catchment.
There's a lot of areas thatstill need similar sort of
management and interventions.
We just finished the four-yearprogram with the Great Barrier
Reef Foundation, which has beenanother highly successful
project, which did one projectin the reach I've been talking
about, but also did projectsmore broadly across the whole
system from Conondale down toTyro, and that program stopped
(38:22):
about 26,000 tonnes of finesediment annually getting out to
the reef.
We're also working on somedisaster recovery reach scale
projects following the floodevents in 2022 in the Mary River
and the tributaries, and we'rejust about to kick off another
round of Australian GovernmentReef Trust funding in the Mary
River, which is another sort offive or six year program of
(38:44):
investment.
So there's a lot of moneythat's been invested in
repairing the Mary River overthe last five to ten years and
looks like it's going to beongoing investment for the next
five to ten years as well.
So, yeah, really, reallyexciting and hopefully we can
get a really much more improvedoutcome for the Mary River than
was 10, 20 years ago.
Siwan (39:05):
Oh, that's wonderful, Really good.
So, listeners, we will put somephotos up there.
But you know, what I love mostabout this story is that you
know it obviously had heartbreakand trauma, but you actually
have managed to.
You know, work with thecommunity.
It's obviously been a bigcommunity initiative to actually
get this river starting to comeback on what we often call a
(39:26):
recovery trajectory, which iswonderful.
And you're still smiling, whichis wonderful, so you're still
excited about what's happening.
This is the great thing aboutworking in rivers.
I think Nature just gives youback so much.
I mean, at least I think itdoes.
I don't know whether you're thesame, but it is for me.
Misko (39:42):
Yeah, and every river, every reach, everything's
different.
That's the thing that keeps itinteresting as well.
The catchment area is different, different.
That's the thing that keeps itinteresting as well.
Yeah, the catchment area isdifferent, the geology is
different, the ecosystemdifferent.
So each different section ofriver, each river, you're
working.
It's a different sort of story,a different puzzle to try and
solve.
Siwan (39:59):
So I love that.
Different puzzles, that'sexactly right.
Well, look, as we come to theend, we have three questions
that we always ask our guests.
So the first one is do you havea favourite river or body of
water?
It doesn't have to be the MaryRiver, you might have somewhere
else.
That's special.
Misko (40:17):
Well, probably from a working perspective, the Mary
River is probably the one I'vedone my most work in.
But seeing you said body ofwater, I'm also a keen surfer so
probably the ocean near where Ilive in northern New South
Wales is probably a favouritebody of water For me anyway.
There, the ocean near where Ilive in northern New South Wales
is probably a favourite body ofwater for me anyway, there's a
bit of time out and surfing andrecreation.
But from a work perspective theMary Rivers is probably a
(40:39):
special spot for me, just theamount of volume of work I've
done in it.
But I've worked on hundreds ofrivers across the East Coast and
everyone's got a special partto it.
Siwan (40:49):
So yeah, and so where do you feel most connected to
nature?
It sounds like it might be on asurfboard, on a break, or is it
a piece of country that youlike to go back to?
Misko (41:02):
Probably in our modern world.
It's probably when we'recamping somewhere where you can
disconnect completely fromtechnology.
You don't have phone receptionand it's relatively isolated.
So I've took my family campingon the Upper Nambuida River in
the national park there earlierthis year in the beautiful gorge
section with a camp right on asort of floodplain pocket there
(41:23):
and beautiful clear, fresh waterto swim in and completely cut
off from the rest of the worldand you feel pretty connected to
nature in those environments.
Siwan (41:34):
Yeah, they're stunning 're stunning.
We do the same.
Actually, I was never a never acamper growing up, but uh, yeah
, we've got a camper trailer nowand it's just getting lost or
not even lost.
It's that sense of awe and uh,certainly not having your phone
near you is absolutely wonderful, so you've made me want to pack
my bags.
You can take me back there.
Mishko, take me to that place,it sounds wonderful.
Misko (41:53):
Yeah, it was a very special spot.
Siwan (41:55):
Well look, thank you so much for taking the time to talk
to us about this fabulousproject and, as I say, the Mary
River was somewhere I wasworking on in the early 1990s,
so it's lovely to hear thatthere's still work going on
there and that it's beingsuccessful.
So thanks again for spendingtime with us and listeners.
We will put some show noteswith Mishko's story so you can
(42:16):
look at some photos, and it justleaves me to say thanks very
much, mishko.
I hope you have a great rest ofyour day.
Thank you and thanks for thechat.
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Hello and welcome to Take Me tothe River where we share
stories and inspire hope withextraordinary people who care
(01:27):
for our rivers.
I'm your host, Dr Shu-AnneLovett.
In this episode, we're divinginto the waters of the Mary
River in Queensland withenvironmental engineer Mishko
Ivozic.
Mishko has been at theforefront of combating river
erosion and sediment issues,which are crucial to the health
of riparian ecosystems and thedownstream rivers that receive
(01:49):
their flow.
Today, we're focusing on aproject Mishko has been working
on on the Mary River.
The Mary River is particularlyimportant because its flows go
out onto the Great Barrier Reefand it has been the source of
significant sediment loads goingout to this very precious
ecosystem.
This project implemented newengineering solutions and
(02:09):
extensive revegetation to reducebank erosion during the 2022
floods.
This story isn't just aboutgeological and riparian
engineering.
It's about ecological recoveryfor threatened species Mary
River Turtle and the Mary RiverCod but it's also about a
community recovering from theimpacts of drastic flooding that
(02:29):
saw their river literallywashed away before their very
eyes.
Join me now as Mishko takes usthrough this incredible
initiative.
Well welcome, Mishko.
It's wonderful to have youjoining us today to talk about a
river that I really love andhaven't been to for quite some
time the Mary River up inQueensland.
Can you tell me a bit about howyou've come to know this river
(02:50):
and why you're interested inrivers?
Misko (02:53):
I'll go back to my interest in rivers first before
I get to the Mary River.
So I'm an environmentalengineer, mainly work in river
management, so around riverprocesses and river river
rehabilitation.
I've been doing that for about15 years, currently based in
northern New South Wales, but mywork is all up and down the
east coast and a little bitoverseas.
So how I've got into this work,I guess I sort of fell into it
(03:18):
in many ways.
Obviously I love rivers andI've spent my childhood playing
in creeks and streams and theNorth Island, new Zealand and
the base of the Mount LoftyRanges in Adelaide.
But I never really imagined youcould make a career out of it
playing in creeks.
But I have managed to.
So yeah, so I basically got toit by studying environmental
(03:39):
engineering at AdelaideUniversity but again I didn't
really know where I was going togo with that degree.
I mainly chose it because I wasgood at mathematics and I cared
about the environment and thenatural world.
Finished that degree and stilldidn't really know where I was
going to go with my work, Istarted a PhD for one year at
Adelaide Uni and that was insort of urban stormwater
(03:59):
management and again didn'treally enjoy that probably
didn't have the maturity to do aPhD in my sort of early 20s.
I applied for jobs in Melbourne,had a friend moving to
Melbourne, applied for jobs andgot a job at Alluvium Consulting
, which was a just a freshly newenvironmental consultant, new
specialist specialized in riverrehabilitation work, so went
(04:20):
over there and I guess, yeah,those first formative years at
Alluvium really developed myinterest in rivers and river
processes and riverrehabilitation, and so how I got
to the Mary River was we'redoing quite a lot of work from
Melbourne in southeastQueensland after the floods that
hit that area in 2011, and so Irelocated up to southeast
(04:41):
Queensland at that time to helpwith all those flood recovery
programs.
And again there was anotherflood in 2013.
And, yeah, I went out to theMary River one day.
I was introduced to thisamazing river system, which I've
now been working on for wellover 10 years.
Siwan (04:59):
I love the fact that you say that you know you were
studying and had no idea whereyou were going to end up,
because I was exactly the same.
I did not expect to be runninga river restoration centre at
all.
There's something about rivers,though.
They just get to you and havingthe opportunity to work with
them and the people that lovethem is fantastic.
I was chatting to Mishkoearlier because I actually
(05:22):
remember the Mary River from mytime in Land and Water Australia
, which is now 20 years ago, andwe had some great projects on
the Mary River, with somefarmers who were fencing off
their stock and doingregeneration work.
Tell me about a site that weactually worked on that now
you've actually gone and workedon, where we'd actually put some
structures into the river totry and control sediment.
Misko (05:46):
Yeah, so this is a site up between Kennedale and not
between Kenilworth and Connedale, and you put in some structures
in the late 90s with BradWedlock from the Mary River
Catchment Coordination Committee, who I still work with very
closely, and so that was aboutputting in some structures along
the toe to protect the bank toefrom erosion and then
revegetating the upper bank, andit's largely been intact over
(06:08):
sort of 20 years later.
But the middle of the sectionhas become quite badly eroded in
recent flood events and so werecently went in there as part
of some funding for protectionof the Great Barrier Reef and
the Great Barrier ReefFoundation and rehabilitated
sort of 200 metre section withinthe middle of that project area
to mainly protect therevegetation works downstream
(06:28):
that were planted in the late90s that are doing really,
really well.
So you know really mature treesnow.
So it's great to see.
Siwan (06:35):
It's a wonderful part of the world because the trees
actually grow quite quicklythere.
We had a project in the MaryRiver and then we went to look
at one in Tasmania and thosetrees were still very little.
Misko (06:47):
So it's great.
You're very right.
Siwan (06:49):
It's a very sort of lucky sweet spot on the east coast of
Australia nice, warmtemperature, lots of rays, and
things grow remarkably quicklythey do indeed, so tell me a bit
more about erosion for some ofour listeners who might not
understand what that actuallymeans for a river in terms of
sediment, and particularly whatcan happen with floods in
(07:10):
systems like this.
So you mentioned, in 2013 therewas another big flood in the
Mary River.
What happened to the river as aresult of that flooding?
Misko (07:19):
Erosion is an essential process in river systems to
start with.
So we often think of erosion asa really really bad thing and
something that needs to bemanaged, but it's a very natural
process and it's fundamental toa lot of the landscapes we see
within our catchments All thehills and floodplains and
everything that's formed fromeither erosion or deposition
over sort of thousands of years,and so an alluvial river is
(07:41):
constantly eroding anddepositing sediment and that
helps form floodplains.
It's really really importantfor agriculture and growing food
.
For us.
It helps scour out pools whichare really important for
maintaining our native fishcommunities and our more broader
fisheries as well.
But often when we, you know,change something within our
catchments and river systems, wecan sort of change those
(08:03):
erosion and deposition processesand sort of mess.
They're sort of in this finebalance, if you like, and if we
mess with things in thecatchment or the riparian zone,
we can tip the balance eitherinto a really erosional phase
where you get really much moreerosion, or a depositional phase
where the channel just fills upwith sands and cobbles and
gravels, and so I'll give it agive you.
One example is the removal ofriparian vegetation.
(08:25):
So vegetation helps stabiliseriverbanks and provide hydraulic
roughness that basically slowsdown velocity and flow up
against the riverbank.
And when we remove thatvegetation from the riverbanks
there's nothing to take up thatexcess flood energy or stream
power and we start to seeerosion of our channels and
widening of the channel, causingloss of floodplains and loss of
(08:48):
those really deep pools thatare so critical for our
in-stream biota.
And I guess another one in theMary River which has caused a
whole lot of issue has been sandand gravel extraction.
So the Mary River was basicallya sand and gravel mine for the
latter part of the 20th century.
Literally hundreds of thousandsof cubic metres of sand and
gravel mine for the latter partof the 20th century and
(09:08):
literally hundreds of thousandsof cubic meters of sand and
gravel were taken out of theriver to support the
urbanization of the sunshinecoast.
And what that does is itdestabilizes the riverbed and it
steepens up the bed profile,leading to an increased slope
and faster velocities and morestream power.
And again, when you get thosebig flood events, water travels
a lot more faster.
Particularly once you govegetation on the banks, you get
really high rates events.
Water travels a lot more fast.
Particularly once you've gotvegetation on the banks, you get
really high rates of channelerosion and channel widening and
(09:29):
a loss of all those reallyimportant habitat features, like
our floodplains and our pools,that are really important for,
yeah, ecological communities aswell as our agricultural
communities as well.
Siwan (09:40):
And I think it's one of those things that you know
humans, we like to fix stuff,and so when we think about
floods, for some people it'sreally a license to get the
water away as quickly aspossible, but that actually then
means that the water createsmore damage because it's not
allowed to slow down and go at alot less speed and a lot less
(10:03):
destructive power when youactually allow it to disperse
more.
So with a catchment like theMary River, so the gravel and
sands has been reduced, it'sstill got sediment coming in,
and then it gets this whack ofwater coming through.
What happened to the river?
Like did it?
Were there big chunks of thebed falling in, or was it just
(10:26):
filled up with sand?
How did it look after thatflood?
That caused people to actuallysay, okay, we've got to do some
more work here.
Misko (10:34):
Yes, the main reach, which we've focused our recent
sort of work on, is around theKenilworth area, but since then
we've obviously been workingacross the whole Mary River as
well, but I'll just describe thechanges around that Kenilworth
reach where we did our originalplan and the majority of our
work.
So what we can gather from youknow, historical information of
the channel, so old surveys thatwere done in the 1950s, and
(10:57):
historical area imagery is thatthe channel bed's lowered by
about two metres, from what wecan tell, since the 1950s, and
its channel width has probablydoubled or in some cases tripled
in width.
So it might have gone from 40 or50 metres wide to well over 100
metres wide in some sections,and the bed's lowered a couple
of metres as well.
So when I went out there afterthe I'm happy to put up some
(11:19):
photos as well when I went outthere after the sort of 2013
flood event, it was just, youknow, sheer vertical cliffs of
10 metres high of loamy, highlyerodible sediments just
collapsing into really turbidwater with high sediment loads
working its way through it, andobviously it's lost all those
really important in-streamhabitat features, like the pools
(11:40):
, which supports a prettyendangered species in the Mary,
like the Mary River Cod and theMary River Turtle, and so it's
basically a basket case.
After that 2013 flood, it wasone of the most degraded rivers
in Australia.
I think it had been called atsome stage in the late 20th
century and at that time it wasjust when the Great Barrier Reef
was coming into focus as a keysort of issue, and it was
probably one of the mostunstable river reaches within
(12:02):
the Great Barrier Reef marinepark catchment areas.
Siwan (12:06):
So a pretty sad and sorry state.
And, listeners, we will putsome photos up so that you can
see that poor old river afterthe flooding.
The connection with the reef Ithink there has been a growing
awareness about the fact that'swhat comes through our estuaries
.
Now onto the reef.
You know people have seenphotographs of plumes, but how
(12:29):
much sediment are we actuallytalking about here, like, does
it really make a huge differenceto the reef?
What's your view on this?
Misko (12:37):
Well, it's different, for every catchment where the
sediment loads are coming from,from the Mary River catchment,
the main source to that area ofthe lower, the southern portion
of the Great Barrier Reef.
It's a very southern catchmentwith the Great Barrier Reef
Marine Park Lagoon and it's yeah, the stream bank erosion has
been estimated to be.
You know, close to half of thefine sediment load getting out
(12:57):
to the reef is coming fromchannel erosion within the Mary
River catchment.
Siwan (13:01):
Wow, that's an enormous amount.
Yeah, so that explains havingsome support from the Great
Barrier Reef.
Was it the conservation fundyou were talking about?
I can't remember the exact name.
Misko (13:12):
Great Barrier Reef Foundation.
Yeah, they invested as apriority.
I couldn't tell you the exactload off the top of my head, but
it's probably tens of thousandsof tonnes every year of fine
sediment coming out the MaryRiver.
Siwan (13:23):
And so when you're talking fine sediment, is that
like tiny granules of sand, likejust for people to have an idea
about what you're meaning byfine?
No, it's even tinier than sand.
Misko (13:35):
It's the clay fraction, so there's clay silt and then
sand as a sort of sedimentclasses.
So it's a really, really finestuff that stays in suspension.
It doesn't really settle outwithin river systems very easily
and is transported insuspension out into the ocean
environment and then eventuallysettles in the ocean environment
and in particular for the MaryRiver, it goes out in the Great
(13:58):
Sandy Strait, which is near Garyor Fraser Island, and so all
that fine clay particles sort ofsettle down in that area and
they're famous for theirseagrass beds and their dugong
sort of areas and all that finesediment smothers those
ecosystems.
Yeah, so when you get theerosion you also get the sand
(14:19):
particles as well, but theygenerally get deposited out in
the river network and they don'tmake it out to the ocean
environment.
Siwan (14:25):
Oh, that's interesting.
So you actually get a range ofsediment that the river's
carrying, but it sort of dropsoff the bigger particles before
it gets right out.
I didn't know that.
So when we see those big plumes, it's that fine suspended stuff
that we're often seeing.
Misko (14:41):
Exactly the coarse stuff still has an impact,
particularly on the river system.
So the sands and gravels andthe coarser things are more
readily visible when you're outlooking at rivers.
That fills up pools and hasimpacts on in-stream habitat
diversity, but it's the fine,really fine clay fractions
that's more important for themanagement of marine
(15:04):
environments.
Siwan (15:05):
So, when it came to designing something to address
this erosion in the Mary River,do you take the sediment profile
into account?
Does that impact on the sort ofdesign that you might develop?
Misko (15:23):
Yeah, definitely.
So you're considering sedimentbeing moved through the river,
on the bed of the channel, butalso the sediment within the
banks, and what sort of profilesneeded to stabilise the
vegetation, and then sort ofsurface treatments as well as
particularly sandy materials.
All that stuff definitely needsto be considered.
Siwan (15:36):
So let's talk specifics then.
What did you actually do withthis project of yours on the
Mary River?
Misko (15:42):
Okay, I'll go back to right at the start.
So you know, I went out thereafter the 2013 flood event and
primarily with Brad Wedlock fromthe Mary River Catchment
Coordination Committee.
As I said, it just looked likean absolute basket case really
of a river and probably at thattime probably didn't ever think
you were ever going to be ableto do anything to address the
(16:02):
issues that you're seeing inthat river.
That's how extreme the problemsseemed.
However, we thought I said weneed to come up with some sort
of plan.
So we got together all the keystakeholders that had an
interest in the river, soBurnett, mary Regional Group,
another regional group workingin catchment management in the
area, sq Water, who's a localwater authority who supplies
(16:22):
water to the township ofKenilworth, and Sunshine Coast
Regional Council, which is thelocal government.
We all got together and we saidlet's come up with a plan for
this particular stretch of river, and I guess the key objective
was to try to increase theresistance of the river so it
would be able to withstand tothe floods of a similar
magnitude that occurred in 2013.
So in that flood event, some ofthe banks migrated over 50
(16:46):
metres, taking out massive areasof really great agricultural
floodplain land and just washingit down the river and out to
the reef the reef.
But there are also some otherobviously ecological outcomes we
wanted to get so by gettingincreased vegetation on the
banks and, over time, returningsome of that in-stream habitat
diversity that supports thosethreatened species I mentioned
(17:07):
earlier.
Siwan (17:08):
It must have been absolutely devastating for the
local community to see thathappen to their river, because I
just know from my working inthe 1990s there there was so
much being done to try and savethe Mary River Turtle and the
Mary River Cod.
So, yeah, you must have beendealing with a highly
traumatized community.
(17:28):
Is that what it felt like toyou?
Misko (17:30):
Yeah, yeah, definitely, and the Mary River Cattle
Conservation Committee arereally great in that aspect of
you know, talking to landholdersand sympathising with them and
building those long-termrelationships.
But, yeah, after thatparticular flood but all flood
events, you get reallytraumatised communities when
they see such drastic change,the changes in the river and
(17:51):
their land as well.
Siwan (17:54):
So, yeah, continue on.
I'm fascinated.
It just struck me that, wow,that must like 50-metre
migration, that is a lot of landto see disappear before you,
and 10-metre high banks as well.
Misko (18:07):
Oh wow, 50 metres by 10, the amount of material that's
coming out is huge.
Yes, we came up with a plan.
So obviously the key goal waswe wanted to get really good
native riparian vegetationgrowing on the banks and in the
channel and on the floodplainagain, and that's going to
provide the long term resistanceto erosion but also all the
other ecological benefits wewant as well.
(18:28):
We have some problems or someareas where the banks were
vertical and 10 metres high andsome of the flood velocities on
those outside bend areas werereally really high.
So planting trees wasn't goingto be feasible by itself.
So we had to come up with someother approaches to support the
revegetation works.
And that's when we look at sortof soft engineering approaches
(18:50):
reshaping banks and putting inlogs or pile structures along
the tow to slow down thevelocity.
So as an engineer working inrivers, I guess my philosophy is
always just trying to do theminimum amount of engineering
that's required to supportvegetation to get established.
So you want the vegetation todo all the work and be the
long-term mechanism that holdsour river channels together.
(19:10):
But you need a little bit ofengineering sometimes to help it
along the way, but not not toomuch.
We're going to be rock lightingriverbanks or over engineering
systems, um, when they don'tneed to.
So a lot of its analysis islooking at the flood, hydraulics
and the geotechnical propertiesand coming up with just the
minimum amount that you'recomfortable with putting in the
system just to help hold ittogether and for the first five
(19:32):
to ten years to allow the timefor the vegetation to get
established.
So with this particular systemwe identified areas where the
velocities were too high or thebanks were too steep and we came
up with some approaches toreprofile the banks back to a
more stable gradient, sort ofone is to three, to allow access
, to revegetate those banks.
And then we installed sort oftimber piles along the tow and
(19:53):
those timber piles act like anartificial forest for the first
five to ten years and slow downthe velocities up against the
toe of the bank and allowsediment and seeds to drop out
in that area as well andregenerate that lower bank zone.
And it just provides enoughresistance in that critical area
for the first sort of 10 to 15years, which then allows the
(20:14):
vegetation to establish on theupper bank and at that point it
doesn't really matter if thetimber piles rot away because
we've got enough vegetation androughness and root reinforcement
in the lower bank, it can helpresist those really big flood
flows and return to more naturalrates of erosion.
We'll still see that erosionand loss of some tree material
(20:34):
that will go into the river andprovide habitat, but it's
nothing like the extreme erosionwe saw in the 2013 flood event,
where some of these banks weremigrating 50 metres.
Siwan (20:46):
So why do you choose to work at the toe of the bank
rather than just focusing on thetop?
Misko (20:53):
The highest forces in a river are down close to the bed
of the river.
So if you've got a big floodflow going, this reach is
greater than 10 metres deep andso the greatest force is right
at the base.
And the greatest force in thebank is obviously at the base of
the river or the bed of theriver up against the toe of the
bank, and that's where you getthe maximum force exerted on the
(21:13):
bank and that causes what iscalled bank toe erosion or
fluvial scour along the toe, andwhat that can do is that
steepens up the bank profileover time until it gets to a
critical point and then it hasgravitational failure.
It comes down to what's calledbank slumping.
So a toe erosion or scour fromthe velocity high velocities of
(21:33):
the toe steepens up the bank andthen you get slumping of the
upper bank material.
So a key thing to stop thatprocess is to provide enough
resistance at the toe.
Toe steepens up the bank andthen you get slumping of the
upper bank material.
So key thing to stop thatprocess is to provide enough
resistance at the toe, where theforces are highest, and then
that will protect the stabilityof the upper bank area where the
actual flood forces are less inthe upper bank and the erosion
there is generally due to thatgravitational mass failure or
(21:55):
bank slumping process.
Siwan (21:58):
It's really interesting, isn't it?
Because, yeah, we focus on thetoe of the bank when we're out
working with farmers as well,but I've certainly been on
stretches of river where you'vegot a really steep bank and
there's one tree just hanging onfor dear life and the farmer
will say that tree's what'scausing that erosion.
You know it's causing the wholething to fall in, and I'm going
(22:19):
that tree is the only thingthat's keeping it up.
Can you explain a bit moreabout that, because it's
counterintuitive for people.
They see a big tree and theythink, oh, that's going to fall
in and pull the bank in with it,but in actual fact, that tree
and its root system is holdingit together.
Misko (22:35):
Yeah, you're right, and it's all the other area around
the tree that's eroded.
It's left that tree standing byitself and the reason that tree
hasn't been able to hold all thebank together is because one
tree can't do all the heavylifting.
You need an army, I guess, isone way of looking at it.
So you need lots of trees andshrubs and ground covers help
holding the bank together, andeach of those three things I
(22:58):
mentioned the ground covers,shrubs and trees do something
slightly different in terms oferosion control.
So your grasses and your groundcovers lay flat and help armour
the underlying alluvialsediments from erosion, provides
a sort of filter layer, if youlike.
So that takes all thehigh-velocity flow force on the
foliage of the grass and theground cover, protecting the
erodible sandy or clay materialunderneath your shrubs, which
(23:22):
have lots of branches andphysical elements.
And physical elements arehighly sort of malleable to move
and get knocked around in floodevents and what that provides
is a lot of frictionalresistance or hydraulic
roughness helps slow down thevelocity, just because the sheer
surface area of all theirlittle small branches and bits
of foliage and then your really,really big trees might not have
(23:42):
a huge impact on the floodvelocities because it's just a
trunk, but it's their rootsystem, is what's happening
underground, and those deeproots and it's almost like
they're providing thereinforcement in the bank prover
like almost like steel andconcrete reinforcement.
Those root systems provide thatreally strong tensile strength
and reduce that mass failure orslumping process I talked about
earlier.
Siwan (24:04):
Yeah, it's a classic one, because you've also got to stop
yourself from saying you'rewrong, because you kind of need
to.
Well, my approach, anyway, isto ask questions about why they
might think that and wherethey've you know.
So you actually are not sayingyou're wrong.
It's more about saying, well,actually, research is showing
this or this or this, so, yeah,it's a better way to go.
(24:26):
In fact, I do remember veryclearly thinking about the
sediment.
I was up on a sugar farm inInnisfail and I was being taken
out to this farm because the guyI was going to see, a guy
called Tom, was known to be avery good riparian manager, and
he took us down to his riparianzone and he had all these
(24:47):
individual trees beautifullypaced apart.
He was mowing around all ofthem, so it all looked very it
was like a garden, and I thought, okay, so that's interesting,
that's the interpretation ofwhat a healthy riparian zone
looks like.
And I left behind him amagazine that I used to produce
at the time called Rip Rap, andit had a whole article on
(25:10):
needing at least a fivecentimetre high swathe of grass
to actually capture sediment.
And so the next day I went backand he went.
So, shu-anuan, I read thatriprap article.
Are you saying that I need tostop mowing as?
much I said yes, I am, but itwas a much better way of going
about it.
And we also then had thediscussion about you actually
(25:32):
need grasses and you need shrubsand you need trees, and it's
that idea that somehow that'sgoing to look messy and it's not
going to actually do as well.
Did you have any resistance inthe community to your approach
to this type of erosion control,or were they sort of fairly
used to that idea?
(25:53):
Did they want more?
Did they want concrete?
Was that going to make themfeel safer?
Misko (25:57):
Every landhold is a little bit different, but I
think at this stage we'll betalking about this project of
the mary river.
At that stage, um, yeah, therewas a lot of uncertainty, I
guess, um skepticism even, but Iguess they had to try something
because they'd seen whathappened from doing nothing.
But moving forward now andseeing the outcome of the, you
know there's been a massivechange in the community and
(26:17):
everyone wants more of this typeof approach and, yeah, I've
convinced many people of thebenefits of this type of work
and the benefits of vegetationmore generally within the
riparian zone.
Siwan (26:28):
Oh, that's great, because I have had people say we just
need green concrete.
That's the environmentalalternative is to go green
concrete.
So let's fast forward then to2022.
There were big floods down theMary River again and I know that
you've recently presented somework to show how your approach
has actually managed towithstand that flooding.
(26:49):
What were you particularlypleased about in terms of how
the river was looking post the22 floods?
Misko (26:56):
I might just go back a bit there in time, if you don't
mind.
Just before what happenedbefore the flood event.
Because, yeah, so we developedup the plan At the time, we
never thought the plan would getfunded.
So that was probably the.
Quite often as consultants, youget paid to develop up plans
and they sit on shelves waitingfor funding and they never get
funded.
So, given the scale of worksthat were required within this
(27:18):
reach, we probably didn't thinkyou know what we were
recommending would ever getfunded.
But then the first funder wasSEQ Water, who their water
offtake for the town was goingto be taken out in the next
flood event if they didn't dosomething to the bank upstream,
the section of bank justupstream of that bank.
So they funded the firstproject and we did that about
(27:38):
2015, which was a major bankreshaping project and
installation of pile fields, asI talked about.
Sunshine Coast Council got theparts of the plan and they
didn't want to really invest inthe engineering or the civil
part of works.
But they jumped at, you know,just going out and fencing and
revegetating all the lower riskareas where the bank was, you
know, more gently sloping anddidn't really need any
(28:00):
engineering or reshaping work.
So they just went to those sortof areas and engaged with
landholders and implemented thefencing and did the planting
works and, as I said, this was atime when the Great Barrier
Reef funding was really sort ofcome online as well, and so, you
know, about five years ago, wegot funding for all the other
really eroding, steeper areasthat needed massive earthworks
(28:21):
and engineering works to supportthe revegetation.
So, slowly but surely, a wholelot of different funders came on
board.
So there was the Queenslandgovernment, there was the
federal government, so,basically, this plan was funded
for a whole range of differentstakeholders over a series of
years, for a whole range ofdifferent stakeholders over a
series of years.
Obviously, most of the work wasimplemented just before the
2022 flood events which camethrough the system.
Siwan (28:46):
That's a great great approach, though, because you
had one plan and one vision, andthen people could say, well,
actually, I'll do this bit, I'lldo this.
So were you sort of theconstant in that, in terms of
being the group to which peoplelook to, to know, okay, if I do
this bit, it's going to work orit's going to fit in with other
(29:06):
stuff that's going on?
Misko (29:07):
with the other stuff that's going on.
So quite early on in theprocess we formed a consortium
between myself and Alluvium, whoI work for, and the Mary of a
Catchment Coordination Committeeand the Burnett Mary Regional
Group or BMLG, and so we formeda consortium and basically we
catch up, you know, everyfortnight or so, and we talk
(29:28):
about the current projects andwe talk about upcoming funding
opportunities we could leverageto invest in the Mary River
catchment.
And so that plan was, you know,a key piece of that exercise to
look for funding opportunities.
And when you're applying forgrants and you've already got a
fully-fledged plan, you're readyto go on some other projects
that have been successful.
It's, you know, looked on muchmore favourably by people um
(29:50):
handing out money for this typeof work makes a huge difference.
Siwan (29:55):
And it also helps, I think, when people move on, if
you still have a plan that a newperson coming in can refer to
or get locked into a newinitiative.
But I know there's so muchgreat work being done around
australia and then when onecrucial, crucial person leaves,
it just falls over and thenyou've got that rebuilding
process.
So I'm delighted to hear that,because I do care about the Mary
(30:15):
River, as I do all rivers, ofcourse.
What about ecological surveys?
You know, my big thing aboutthe Mary River turtle, of course
, is it's a bottom-breathingturtle, so it's got a cloaca.
If no one has seen or heardthat word before, you might not
want to see it.
But yeah, I always think aboutthe bottom breathing turtle,
which is the Mary River.
(30:35):
So what have you learned fromthe ecology?
Misko (30:39):
With ecological surveys.
A big part of what we need todo is part of this work.
So I don't necessarily dealwith that directly, but Mary
River Catchment CoordinationCommittee they're really on top
of doing those surveys before wedo works and while we're doing
works as well.
Because quite often whathappens when we are reshaping or
reprofiling these banks?
The Mary River Turtle lovesnice sandy nesting environments
(31:00):
so we turn a vertical cliffthat's no good for Mary River
Turtle habitat into a nicereprofiled sandy bank and they
sort of run for it and want todo all their nesting there.
But unfortunately we're alsotrying to install piles and do
other things.
So it's quite often during thatearly construction phase we've
got to put up exclusion fencesfor that month or so just to try
(31:21):
and stop them getting onto thebank, to enable us to finish the
works and do the planting andthen they can go for it.
After that they can create abit of a turtle sanctuary for
them.
With this nice, gently slopingbank they can climb up nice and
easily compared to the verticalbank.
So it does take a few headachesduring construction trying to
manage those turtles trying toget up onto these banks and
trying to limit their accesswhile we can.
(31:42):
But yeah, over time we'reimproving their habitat,
providing those more gentlysloped banks that accumulate
sediment and sand, which theylike for their nesting.
Siwan (31:51):
It's almost like you know you've got one of those
billboards coming soon.
You know like don't try now, interms of real estate in the
river, this is going to be thepremier estate, but you have to
make us build it first.
And what about the cod?
Because the cod needs deepholes.
Some of these structures thatyou're putting in not only would
(32:12):
be holding back sediment ormaking it more structurally
sound, but is it also enablingsome scouring to get back a bit
more of those deeper pools thatfish like yeah, it's a bit of a
slower process for the cod.
Misko (32:24):
Because the Mary River has got so wide over several
decades it's lost the ability tomaintain those deeper pools.
And basically how a river scoursout and maintains pools it has
to have a lot of roughness onthe banks.
You imagine really densityvegetated river banks.
It forces flood flows betweenthe vegetation and that helps
scour out the bed and maintainthose pool environments.
(32:44):
And as the river gets wider andwider you don't have
necessarily the force within thebed of the channel to scour out
those pools and maintain thosedeep areas.
So unfortunately a lot of theMary River is a very shallow
river now and a lot of thosedeeper pool areas where the cod
still remains are in thetributaries.
So over time as the vegetationestablishes on the banks and
(33:05):
encroaches more and more in thechannel and on the bars,
hopefully over time you knowthat's probably going to be
decade timescales we can getenough roughness in the channel
back again that we can start toscour out an insect low flow
channel a bit more and providethat bed diversity and habitat
for the cod.
But it's a bit slower process.
It's going to take decadesunfortunately to undo all the
(33:28):
damage that's been done to beddiversity in the Mary River.
Siwan (33:36):
Yeah.
I think, though, that really,if we think, decades is a long
time, it's not actually thatlong in the life of a river.
So I've been doing some workwith traditional owners, who
have a 100 year plan for aparticular river, and I'm
thinking that's actually muchmore sensible, because we do
place a lot of pressure onourselves to get things done
quickly, but nature does respondmore slowly, but probably with
a longer term view in terms ofit being there for much longer
(33:59):
than we're around.
I'm interested with the 2022floods.
What happened in terms of theamount of sediment that was
moving, and were you able to,you know, report back to the
Great Barrier Reef Foundationthat you'd actually managed to
stop some sediment getting outonto the reef?
Misko (34:18):
So 2022 was a wet year across the east coast.
We had a series of smallerfloods in the Mary River, which
culminated in the biggest floodin sort of May 2022.
And so this through the REACHwe worked on, I think.
The flood peak was well over 10to 12 metres high and it was
basically the biggest flood thathad occurred in the system
since the 1990s, so well over 30years.
(34:39):
It's much bigger than the eventin 2013, which instigated all
these projects, and so I thinkthe flood event occurred over a
weekend, so it was a nervousweekend for myself.
I was checking BOM constantly onmy phone and looking at river
heights and rainfall andmonitoring all the gauges and
imagining all these structuresand things that I'd put in the
(35:00):
riverbed that were now 12 metresunderwater and imagining what
was happening to them and howthe sediment was moving through
them.
But I was pretty nervousbecause obviously we'd
implemented millions of dollars'worth of rehabilitation works
in just the years before thisflood event.
So obviously you're reallyquite nervous.
What's happened to all thatinvestment and hundreds of hours
of hard work that you've putinto it?
(35:21):
And so I didn't get out therefor a few weeks, but the few
days after the flood, um Bradfrom MRCCC, um his colleagues,
colleagues did a walk down thereach and I remember being at
work he was sending me textmessages and photos of each
section to see how it stood up.
Suspense was killing me as hewalked around every bend to see
(35:42):
what we were going to see.
But as the photos kept coming in, I just got a bigger smile on
my face because everythinglooked great and the trees were
still there.
They were banged around a bit,but they were largely intact,
and some of these banks that hadmigrated 50 metres nearly 10
years earlier were basicallylargely intact, with very little
deposition.
And then he kept sending methese photos of his gumboots
(36:02):
sinking into all the silt thathad been captured on the banks
as well.
So not only had we stoppederosion on the banks, but all
the vegetation and roughness wewere adding was capturing sands
and silts on the bank as well,so they were basically
accumulating sediment.
So what had been really bigsediment sources were now
becoming these sedimentaccumulation zones and capturing
sediment on the banks.
So everything held up reallyreally well.
It was managed to get out thereand since then we've done a
(36:24):
whole lot of more quantitativeanalysis and collected LiDAR
data of the reach and comparedthe change in the bank
morphology before and after theflood.
And so yeah, we estimate, youknow, sort of effectiveness of
the works is, you know, in therange of sort of 80 to 90%
sediment reductions going fromthe reach and out to the Great
Barrier Reef.
So really really highlyeffective projects at stopping
(36:48):
sediment getting out to the reef.
Siwan (36:50):
That's incredible.
What sort of?
Have you got any idea of sortof tonnes that might mean more
to our listeners?
I mean, the percentages aresuper impressive.
Yeah, so from this, particularbreach.
Misko (37:03):
This is about a sort of four kilometre sort of breach we
primarily did this analysis on.
We're sort of basicallystopping 20,000 cubic metres of
sediment in total each year onaverage and going out to the
reef.
That's, you know, assumingabout half of that's fine
sediment that gets out to sortof the reef environment, so sort
of 10,000 cubic metres.
So that's close to almost, youknow, 15 to 20,000 tonnes of
(37:25):
fine sediment going out to thereef each year.
That we've managed to stop fromthese works.
That's sensational, that's sogood.
I can just imagine you, youknow, seeing gumboot photos and
smiling more and more and peoplegoing.
Siwan (37:40):
Why are you excited about a gumboot in?
Misko (37:42):
sediment River engineers get excited about strange things
.
Siwan (37:46):
They do indeed, they do indeed.
So what are you doing in termsof ongoing work with the Mary
River?
You said you've formed thisconsortium, so you're obviously
still talking.
So what are the plans for theMary River going forward?
Misko (38:00):
Yeah, we're still talking and it's a big catchment.
There's a lot of areas thatstill need similar sort of
management and interventions.
We just finished the four-yearprogram with the Great Barrier
Reef Foundation, which has beenanother highly successful
project, which did one projectin the reach I've been talking
about, but also did projectsmore broadly across the whole
system from Conondale down toTyro, and that program stopped
(38:22):
about 26,000 tonnes of finesediment annually getting out to
the reef.
We're also working on somedisaster recovery reach scale
projects following the floodevents in 2022 in the Mary River
and the tributaries, and we'rejust about to kick off another
round of Australian GovernmentReef Trust funding in the Mary
River, which is another sort offive or six year program of
(38:44):
investment.
So there's a lot of moneythat's been invested in
repairing the Mary River overthe last five to ten years and
looks like it's going to beongoing investment for the next
five to ten years as well.
So, yeah, really, reallyexciting and hopefully we can
get a really much more improvedoutcome for the Mary River than
was 10, 20 years ago.
Siwan (39:05):
Oh, that's wonderful, Really good.
So, listeners, we will put somephotos up there.
But you know, what I love mostabout this story is that you
know it obviously had heartbreakand trauma, but you actually
have managed to.
You know, work with thecommunity.
It's obviously been a bigcommunity initiative to actually
get this river starting to comeback on what we often call a
(39:26):
recovery trajectory, which iswonderful.
And you're still smiling, whichis wonderful, so you're still
excited about what's happening.
This is the great thing aboutworking in rivers.
I think Nature just gives youback so much.
I mean, at least I think itdoes.
I don't know whether you're thesame, but it is for me.
Misko (39:42):
Yeah, and every river, every reach, everything's
different.
That's the thing that keeps itinteresting as well.
The catchment area is different, different.
That's the thing that keeps itinteresting as well.
Yeah, the catchment area isdifferent, the geology is
different, the ecosystemdifferent.
So each different section ofriver, each river, you're
working.
It's a different sort of story,a different puzzle to try and
solve.
Siwan (39:59):
So I love that.
Different puzzles, that'sexactly right.
Well, look, as we come to theend, we have three questions
that we always ask our guests.
So the first one is do you havea favourite river or body of
water?
It doesn't have to be the MaryRiver, you might have somewhere
else.
That's special.
Misko (40:17):
Well, probably from a working perspective, the Mary
River is probably the one I'vedone my most work in.
But seeing you said body ofwater, I'm also a keen surfer so
probably the ocean near where Ilive in northern New South
Wales is probably a favouritebody of water For me anyway.
There, the ocean near where Ilive in northern New South Wales
is probably a favourite body ofwater for me anyway, there's a
bit of time out and surfing andrecreation.
But from a work perspective theMary Rivers is probably a
(40:39):
special spot for me, just theamount of volume of work I've
done in it.
But I've worked on hundreds ofrivers across the East Coast and
everyone's got a special partto it.
Siwan (40:49):
So yeah, and so where do you feel most connected to
nature?
It sounds like it might be on asurfboard, on a break, or is it
a piece of country that youlike to go back to?
Misko (41:02):
Probably in our modern world.
It's probably when we'recamping somewhere where you can
disconnect completely fromtechnology.
You don't have phone receptionand it's relatively isolated.
So I've took my family campingon the Upper Nambuida River in
the national park there earlierthis year in the beautiful gorge
section with a camp right on asort of floodplain pocket there
(41:23):
and beautiful clear, fresh waterto swim in and completely cut
off from the rest of the worldand you feel pretty connected to
nature in those environments.
Siwan (41:34):
Yeah, they're stunning 're stunning.
We do the same.
Actually, I was never a never acamper growing up, but uh, yeah
, we've got a camper trailer nowand it's just getting lost or
not even lost.
It's that sense of awe and uh,certainly not having your phone
near you is absolutely wonderful, so you've made me want to pack
my bags.
You can take me back there.
Mishko, take me to that place,it sounds wonderful.
Misko (41:53):
Yeah, it was a very special spot.
Siwan (41:55):
Well look, thank you so much for taking the time to talk
to us about this fabulousproject and, as I say, the Mary
River was somewhere I wasworking on in the early 1990s,
so it's lovely to hear thatthere's still work going on
there and that it's beingsuccessful.
So thanks again for spendingtime with us and listeners.
We will put some show noteswith Mishko's story so you can
(42:16):
look at some photos, and it justleaves me to say thanks very
much, mishko.
I hope you have a great rest ofyour day.
Thank you and thanks for thechat.
You can subscribe to Take Me tothe River.
Wherever you get your podcasts,visit arrcau forward slash
podcast to learn more.
(42:37):
That's arrcau forward slashpodcast.
We acknowledge and respectAboriginal and Torres Strait
Islander peoples as thetraditional and continuing
custodians of the country andthe rivers on which we live,
learn, love and play.
We respect and learn fromElders, past, present and
(42:58):
emerging, valuing theirknowledge, insights, cultures
and connections to the waterwayswe all love and care for.
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