Illawarra Flash Flood Event - August 1998

This was serious event were some falls over the 3 days accumulated well over 500 mm ( 20 ins)

7th & 8th AUGUST - MINOR FLOODS, GALE FORCE WINDS and LARGE SEAS. A trough that had brought rainfall to inland New South Wales moved offshore and formed a low depression on Thursday 6th. Friday the 7th saw gale force winds develop and these lasted 36 hours as the low which was expected to move rapidly SE, slowed and actually move NE. Winds were recorded at 65 knots by the Port Kembla signal station on Friday evening. Surprising little damage was recorded, although homes were blacked out in some areas. Parts of Robertson on the escarpment were without power for over 18 hours. Rainfall varied throughout the Illawarra, but was almost everywhere over 150mm for the entire event. I did hear an unconfirmed report of over 300mm for Kangaroo Valley. Several roads in the area were cut, but only for a short time. The winds generated quite large seas, prompting the Bureau to issue a storm surge / large waves warning. Waves peaked at around 20ft ( 5-6m ) on exposed coasts. Damage and erosion however was minimal, the media did a great job of sensational reporting in regard to the waves, being an experienced ( former ) surfer I can tell you that seas reach this size once or twice in most years. The video stills below show the waves hitting Port Kembla harbour breakwater on the Saturday ( 8th ). For some size perspective each of the cement blocks is 6-7ft high.

That's not a lake !Port Kembla South BreakwaterNo fishing today !



Radar images courtesy of the Bureau of Meteorology

The first image is at approx 6pm on the 17th August 1998. This was about 30 mins before the storm grow to peak intensity. But already it shows areas of up 100mm per hour rainfall.

The second image is 8am the next morning and clearly shows the trough line, now just offshore. I live just below the label WOL and it was overcast with rain. Michael Bath of Australian severe weather who was located on the 16th floor at his work site ( right between the label SFS and BK ) was in sunshine and had a fantastic view of stacked Cumulonimbus cells to the east and south. See link below for Michael's account of the storm.


On Monday evening at about 7.00pm I observed that the rain was
incredibly intense compared with earlier in the day - the rate of run
off down my the backsteps behind my home seemed to have trebled or
quadrupled compared with what I had seen earlier  during the day which I
had  thought had already  been about the highest flow rates that I had
ever observed.
I went to move my car from the street to higher ground - I had been in
bed with the flu and hence not at a Wollongong City Council meeting -
but it was too late - my neighbours were alerting us of the flood that
had occurred and that my car was underwater up to its headlights. I went
out and looked and realised instantly that we had pmf (probable maximum
flood height level) - I had only recently chaired a public meeting in
Thirroul on my catchment Hewitts Creek Flood Study and was well aware of
where 1in 100 year flood levels and the pmf would be - I was also
instantly aware that across the whole of Wollongong that we would be in
big trouble. I tried to contact relevant senior engineers at Council on
their mobile phones to seek evacuation assistance for my neighbours -
none was available - individual communities throughout the city of
Wollongong were isolated - each would have to help itself and evacuate
sooner rather than later. Eventually a senior engineer rang back and
updated me - just as he and others at the SES headquarters had to be
evacuated themselves  - SES volunteers were to find their cars under
water as well. Remarkably the flood level dropped quickly - thank
goodness - and I was able to move my car to higher ground and then start
to move furniture upstairs - my husband was trying to get back to Sydney
- having been stuck on the F6 and no hope of getting down Bulli Pass. I
began to watch the television reports including the stories of the kids
escaping from the roof - I made contact with the Lord Mayor - we were
both very worried.

I had always hoped that I would never see a pmf anywhere in the City of
Wollongong in my lifetime - let alone in my own neighbourhood.

I sleep badly and get up at 4.00am and 5.00am to check up on the creek
and sea levels -thank goodness the tide is not too high and the storm
surge is not too bad. I go home and sleep deeply for another 2 hours -
at 7.00am my daughter wakes me up - I don't want to get up yet - I know
that it will be a long day.

Next day began the task of the clean up.

So many people helped us the next day - we were without running water
for 21 hours and buried in a sea of sticky mud - and there would be no
power in some of the flooded houses for another 24 hours - I tried to
bail out the water and mud from my car plus deal with engineers
recording flood heights and stressed neighbours worried whether their
property would be undermined as the creek banks had been eroded away.

It seems to go on and on - I walked up to Lachlan St Thirroul - further
up the catchment of my creek - what a disaster area - in my street there
had been a sea of mud but up here was structural damage and a fear about
more storms due and creeks full of rock and mud - fortunately we escaped
any severe aftermath of more storms.   My husband finally makes it back
to Wollongong and finds me on the streets of Thirroul walking back to
our home as the rain begins to pour down again. At home - I finally
shower and it's 4.30pm and at last  I feel hungry - I had not eaten or
drunk anything all day.

With each day there was more news  of tragedy and heartache. And in the
early hours each morning I would wake and relive the experiences - and
think of all the things that I had to do following the flood's aftermath
- both on  a personal basis and also as the local City Councillor. On
Thursday afternoon at 4.30pm I was still cleaning the kitchen of a
property I own opposite my home- the mud is so sticky and requires
scrubbing to remove - my tenants had lost nearly everything in the flood
from this property.  I had to quickly get changed  to attend a special
meeting of Wollongong City Council convened for 5.00pm to report on the
disaster. I really found it hard to attend - but knew that I had to go -
I listened to the reports and gave an emotional thankyou to all those
who had helped my neighbours and myself. I finally returned to work on
Friday - which was good to get away from the flood - but it was never
far away in my thoughts - I was agitated when it began to rain on the
way home.

On Saturday I got ready to listen to the 7.00am news - fearing what more
tragic news might emerge and predictably it did - my fellow Ward
Councillor Dave Martin had to evacuate his home for fear of landslides -
and then came the warnings of more bad weather and floods over the radio
- I was frantic - raising the few remaining belongings of my tenants
above a flood height and alerting neighbours to be careful - a Council
engineer and SES officer came and said that everything was looking more
optimistic -  thank goodness - the thunderstorms broke up and moved away
- and the sun came out and everything became a little drier. And Dave
Martin had the "OK" to re-occupy his house.

But the tragedy endures - and our own flood problems (minor compared to
many) require obtaining quotes and organising repair work -plus  more
cleaning of curtains and repainting - and the mud and the water linger -
unable to get away because it starts to rain again - maybe tomorrow it
will dry out - but then there are more storm warnings - for the early
hours of Sunday morning - it will take a long time to recover for many
residents - and the engineers continue to collect and analyse the data
to try to explain what's happened....

Fairy Creek, North Wollongong.

Springhill Road, Port Kembla, covered in slimey mud

Two photos taken the day after the floods. The first is where Fairy Creek enters the ocean at North Wollongong, the day before from where the photo was taken right across to the far side of the rocks was a sandy beach. The flash flood from fairy Creek has scoured the beach down to bedrock. This is a creek whose farest flung headwater is less than 5 miles away. The second is traffic chaos at Springhill Road, Port Kembla, although just outside the main flood area this stretch of road as far as you can see in this photo was flooded to at least 1m ( 3ft ) deep, left behind was a slimy mud that caused traffic accidents.

Where did the road go ?19th August 1998 - RAIN PERSISTS, ILLAWARRA HWY AND PRINCESS HWYS STILL CUT - Rain fell steadily overnight in the southern Illawarra, thankfully not the torrential showers of yesterday evening or Monday. During the day the rain broke to showers, which at times were briefly heavy. The overnight rainfall in the Kiama to Jamberoo area was enough to slightly rise the level of Minnamurra River and the Princess Hwy was cut south of Dunmore where there is no alternate route. To the north of Dunmore the Hwy remained fully closed to all but heavy vehicles. Emergency services personnel were helping guide motorists through the water south of Dunmore, this was wise as I had witnessed too many Yahoos ploughing into water over the last few days. I own a large diesel 4WD and took it easier through the water then some conventional car owners. It's not just because I'm cautious, I also consider other motorists and in flooded suburban streets you should also consider the that the wave you make may be splashing into somebody's front door. The photo shows the flooding, and the result for unfortunate motorist who lost the edge of the road.

20TH August - LANDSLIDE FEARS - A resident of the village of Mt Kembla was woken early in the morning by his barking dog. When he went outside he could hear trees snapping as a landslide tumbled down the mountainside. Several homes were evacuated. Residents were allowed back later in the afternoon after a geo-technical survey indicated that should a major landslide occur, the debris would miss the houses. Rockfalls and landslides are no stranger to the Illawarra, but the last weeks rains has made the situation worse.

30th August - RAINFALL RECORDS TUMBLE - August rainfall broke all records in the Illawarra, in some cases by double. Wollongong University recorded 763mm ( 30 + ins ) for the month. Other stations in the Illawarra were Kiama 728mm and Darkes Forest 744mm. With Wollongong almost half the rainfall fell in the flash flood of the 17th August 1998. In the case of Kiama the record is significant in that several heavy rain events contributed.

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