NSW/ACT Persistent Easterly Trough followed by inland trough March 17-24, 2021

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Crispy013

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Another 60mm last 24hrs in Port Mac. Most of that falling in the early morning.

430mm+ in last 4 days. Not easing up based on the next moisture train sliding south. Windy AF at the moment too.

j51ByWw.jpg
 

dawooduck

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To put it into perspective - One day of those flows would fill Menindee Lakes
Also - Sydney Harbour is 500GL - so 1.5 days of that would fill it too.

The measure of a healthy environment would be the regular natural filling of Menindee Lakes, alas, the powers in charge are actively working towards Menindee Lakes being taken off line permanently.
 

Yogurt_FreeZone

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Dec 28, 2020
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http://www.bom.gov.au/nsw/warnings/flood/nepean-hawkesburyrivers.shtml
Latest River Heights:
Location Height of River (m) Tendency Date/Time of Observation
Nepean River at Menangle Bridge 8.49 Steady 08:32 AM SUN 21/03/21
Nepean River at Penrith 8.23 Rising 07:44 AM SUN 21/03/21
Grose River at Burralow 6.11 Steady 08:48 AM SUN 21/03/21
Hawkesbury River at North Richmond WPS 11.88 Rising 08:35 AM SUN 21/03/21
Hawkesbury River at Windsor PWD 9.28 Rising 07:45 AM SUN 21/03/21
Colo River at Upper Colo SWC 11.44 Steady 08:49 AM SUN 21/03/21
Macdonald River at St Albans 4.98 Steady 08:47 AM SUN 21/03/21
 

Steve777

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Mangrove Mountain (Central Coast hinterland) has had 35 mm since 9:00.

CORRECTION: “Portable” sites in Sydney’s NW were apparently showing readings for 24 hours to 9:00 - had not yet been reset.
 

davidg

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150mm to midnight yesterday and we've had another 90mm since midnight here in Glenbrook. It's still coming down at around 20mm an hour.

North Richmond already past the Major flood level at 11.2m and climbing. The Nepean river will probably hit the major flood level at Penrith as well today. That doesn't bode well for those down stream.
Now 145mm since midnight! This is(was) the weir at Penrith. Some big trees coming down the river, the speed the water is moving out in the middle is crazy.
20210321_094934.jpg
 

Snow Blowey

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The measure of a healthy environment would be the regular natural filling of Menindee Lakes, alas, the powers in charge are actively working towards Menindee Lakes being taken off line permanently.

Rubbish. Menindee was always going to fill again when it started raining. In 2019 there was no natural flow anywhere in the Darling catchment. That includes above and below water storage.

Like i said at the time. It will rain again, major flood events will happen again. At those times there is plenty of water to flush the river, recharge groundwater and to be stored for later use (and for later release into the next dry period. When you let all the runoff flow out to sea unused you waste it.
 
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Steve777

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Abercrombie Rd from Oberon to Taralga closed.
Bridge 1.5 M underwater.
Upper BMs 250 mm so far from the system.
All in the upper Sydney catchment.
I thought I’d check Katoomba. Katoomba has received 210 mm in the six days to 9:00 yesterday and a further 168 mm in the 24 hours to 9:00 today, for a total of about 380 mm in a week with more to come.

My understanding of the geography of the area is that rain falling North and West of the ridge of the Blue Mountains (roughly, the Great Western Highway and Darling Causeway) flows into the Grose River which joins the Nepean-Hawkesbury River above Richmond. That falling West and South falls in the Warragamba cachment.
 

Snow Blowey

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Coxs River at Kelpie Pt up to about 5.5m which is 150,000ML/day on the rating curve.

Water NSW site is done now.

Looks to be lots flowing in on the Wollondilly side also.

Chart for penrith earlier this morning indicated over 500,000ML/day passing that gauge.
 
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dawooduck

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Rubbish. Menindee was always going to fill again when it started raining. In 2019 there was no natural flow anywhere in the Darling catchment. That includes above and below water storage.

Like i said at the time. It will rain again, major flood events will happen again. At those times there is plenty of water to flush the river, recharge groundwater and to be stored for later use (and for later release into the next dry period. When you let all the runoff flow out to sea unused you waste it.


Offline is not natural flow and "engineered solutions" are not undertaken for environmental gains. The Lakes will die and as your comment "When you let all the runoff flow out to sea unused you waste it" indicates the lakes are of little importance to industry

 
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sbm_

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Hopefully not too alarmist but I have to show this incredible quote from the 1867 flood from a witness in the northern beaches in @robbo mcs link.

"At the confluence of the Mangrove with the Hawkesbury, the latter presented on Friday, Saturday, and Sunday an awful sight - one that cannot be soon forgotten. It was rushing on with astounding rapidity, conveying down houses, stacks, cattle, pigs, ducks, geese, hens, chairs, tables, doors, boxes, beds, and bedsteads - even a child, seated on a bag of flour, was seen going down the river.

There must have been awful havoc in the Hawkesbury, for all the beaches from Barrenjoey to the Long Reef are strewed with fragments of houses, boxes, chairs, door frames, dead pigs, hay, wheat, broken bedsteads, weather board sides of houses, oranges with large branches, pumpkins, melons, corn cobs, and other debris, that scarcely any portion of the beaches can be seen."
 

Snow Blowey

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Offline is not natural flow


Neither is the rainwater tank coming off your shed. Humans are smart enough to capture water in times of plenty so a more reliable supply is available in dry times. Seems smart to me to store as much water as possible as high up the catchmment as possible. Once the river floods, excess water out to see is wasted. Can't you see that. It achieves nothing but replenishing the big salty pond south of Goolwa.
 
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dawooduck

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Neither is the rainwater tank coming off your shed. Humans are smart enough to capture water in times of plenty so a more reliable supply is available in dry times. Seems smart to me to store as much water as possible as high up the catchmment as possible. Once the river floods, excess water out to see is wasted. Can't you see that. It achieves nothing but replenishing the big salty pond south of Goolwa.

Your suburban priorities are well noted. The coastal flood plains now being replenished naturally are okay but inland its use it or loose it and the environment be ..... damed.

The koalas and pelicans can just go live somewhere else.
 

Richard

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Hopefully not too alarmist but I have to show this incredible quote from the 1867 flood from a witness in the northern beaches in @robbo mcs link.

"At the confluence of the Mangrove with the Hawkesbury, the latter presented on Friday, Saturday, and Sunday an awful sight - one that cannot be soon forgotten. It was rushing on with astounding rapidity, conveying down houses, stacks, cattle, pigs, ducks, geese, hens, chairs, tables, doors, boxes, beds, and bedsteads - even a child, seated on a bag of flour, was seen going down the river.

There must have been awful havoc in the Hawkesbury, for all the beaches from Barrenjoey to the Long Reef are strewed with fragments of houses, boxes, chairs, door frames, dead pigs, hay, wheat, broken bedsteads, weather board sides of houses, oranges with large branches, pumpkins, melons, corn cobs, and other debris, that scarcely any portion of the beaches can be seen."


As usual, our forum threads in times like these are both a more useful and a more interesting stream of reporting than mainstream news blogs.
 

Richard

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Our high-tech rain gauge recorded 98mm in the 24hr to 9am this morning. 37mm yesterday 9am (19th) and 22mm Thu 18th for total of 157mm last 3 days.

19mm to 9am this morning here (Clarence Town), but yesterday was mostly clear of rain with light rain in the evening and overnight - has been steady rain since about 8:30am til just now.
 

Untele-whippet

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I thought I’d check Katoomba. Katoomba has received 210 mm in the six days to 9:00 yesterday and a further 168 mm in the 24 hours to 9:00 today, for a total of about 380 mm in a week with more to come.

My understanding of the geography of the area is that rain falling North and West of the ridge of the Blue Mountains (roughly, the Great Western Highway and Darling Causeway) flows into the Grose River which joins the Nepean-Hawkesbury River above Richmond. That falling West and South falls in the Warragamba cachment.
250 mm Thursday 9.00 am - Sunday 9.00 am measured at Mt Boyce, that side drains to Warragamba.
Still pi$$ing down.
 

Flowin

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Coxs River at Kelpie Pt up to about 5.5m which is 150,000ML/day on the rating curve.

Water NSW site is done now.

Looks to be lots flowing in on the Wollondilly side also.

Chart for penrith earlier this morning indicated over 500,000ML/day passing that gauge.
This the last Penrith gauge plot I was able to get
That website is very slow ATM
upload_2021-3-21_10-19-58.png
 
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Legs Akimbo

Grumblebum
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Hopefully not too alarmist but I have to show this incredible quote from the 1867 flood from a witness in the northern beaches in @robbo mcs link.

"At the confluence of the Mangrove with the Hawkesbury, the latter presented on Friday, Saturday, and Sunday an awful sight - one that cannot be soon forgotten. It was rushing on with astounding rapidity, conveying down houses, stacks, cattle, pigs, ducks, geese, hens, chairs, tables, doors, boxes, beds, and bedsteads - even a child, seated on a bag of flour, was seen going down the river.

There must have been awful havoc in the Hawkesbury, for all the beaches from Barrenjoey to the Long Reef are strewed with fragments of houses, boxes, chairs, door frames, dead pigs, hay, wheat, broken bedsteads, weather board sides of houses, oranges with large branches, pumpkins, melons, corn cobs, and other debris, that scarcely any portion of the beaches can be seen."
Sailing in Broken Bay and offshore was always a little fraught with even a moderate Hawkesbury flood. You were never sure what might be bobbing around.
 

davidg

Part of the Furniture
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Feb 4, 2009
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Hopefully not too alarmist but I have to show this incredible quote from the 1867 flood from a witness in the northern beaches in @robbo mcs link.

"At the confluence of the Mangrove with the Hawkesbury, the latter presented on Friday, Saturday, and Sunday an awful sight - one that cannot be soon forgotten. It was rushing on with astounding rapidity, conveying down houses, stacks, cattle, pigs, ducks, geese, hens, chairs, tables, doors, boxes, beds, and bedsteads - even a child, seated on a bag of flour, was seen going down the river.

There must have been awful havoc in the Hawkesbury, for all the beaches from Barrenjoey to the Long Reef are strewed with fragments of houses, boxes, chairs, door frames, dead pigs, hay, wheat, broken bedsteads, weather board sides of houses, oranges with large branches, pumpkins, melons, corn cobs, and other debris, that scarcely any portion of the beaches can be seen."
Over on the Castlereagh side of the railway line there's a pole about 6m high with the 1867 flood level marked on it. I was keen to head down there today but Castlereagh road has flooded under the new railway bridge. Could go the long way via Northern Road but wasn't that keen.

Only a matter of time before the GWH at Peachtree creek goes under as well. It's about 50cm below the bridge so when the Nepean continues to rise it'll back up and flood the road
 

robbo mcs

A Local
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Hopefully not too alarmist but I have to show this incredible quote from the 1867 flood from a witness in the northern beaches in @robbo mcs link.

"At the confluence of the Mangrove with the Hawkesbury, the latter presented on Friday, Saturday, and Sunday an awful sight - one that cannot be soon forgotten. It was rushing on with astounding rapidity, conveying down houses, stacks, cattle, pigs, ducks, geese, hens, chairs, tables, doors, boxes, beds, and bedsteads - even a child, seated on a bag of flour, was seen going down the river.

There must have been awful havoc in the Hawkesbury, for all the beaches from Barrenjoey to the Long Reef are strewed with fragments of houses, boxes, chairs, door frames, dead pigs, hay, wheat, broken bedsteads, weather board sides of houses, oranges with large branches, pumpkins, melons, corn cobs, and other debris, that scarcely any portion of the beaches can be seen."

Yep, some pretty powerful accounts in that article. Interesting about the windblown swell and waves on the massive “sea” that formed. The bit about the Eather family is so tragic. I often ride my bike around Richmond lowlands / Cornwallis, and everytime I go past the memorial it gives me the chills. Also, hard to comprehend that that area was nearly 20m under, so probably above the telegraph poles in this photo
5C2F63B8-DC01-4DF3-9974-0385001E0EC4.jpeg


The meteorological stuff in that article is also really interesting. Only one of the major recorded floods was not due to an ECL.
 

Nidecker

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Sailing in Broken Bay and offshore was always a little fraught with even a moderate Hawkesbury flood. You were never sure what might be bobbing around.

The NSW optimist association and RPAYC managed to get 2 races in yesterday in pittwater, probably 9-13yr olds. Not sure whether to say well done or not, but would have been "character building". I will say knowing both associations the kids would have been very safe.
 

Mogul

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Neither is the rainwater tank coming off your shed. Humans are smart enough to capture water in times of plenty so a more reliable supply is available in dry times. Seems smart to me to store as much water as possible as high up the catchmment as possible. Once the river floods, excess water out to see is wasted. Can't you see that. It achieves nothing but replenishing the big salty pond south of Goolwa.
And bugger those lower down the catchment.

Cubby Station anyone.
 

Donza

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The NSW optimist association and RPAYC managed to get 2 races in yesterday in pittwater, probably 9-13yr olds. Not sure whether to say well done or not, but would have been "character building". I will say knowing both associations the kids would have been very safe.
Well they were optimists
 
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warrie

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As usual, our forum threads in times like these are both a more useful and a more interesting stream of reporting than mainstream news blogs.
Agree in general but if only we could get ALL the facts accurately every time LOL. To pinch a quote seen on S and T. "Facts are stubborn things."
— John Adams, 1770
 

derider

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Its a pity Bellambi is down.

Not that we've had anything extraordinary here. Mostly light drizzle mixed in with some heavier showers, but certainly nothing news worthy. It's actually been very disappointing considering the forecasts. I was led to expect a much more intense event.
 

Legs Akimbo

Grumblebum
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Mar 3, 1999
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Coastal suburban boonies.
The NSW optimist association and RPAYC managed to get 2 races in yesterday in pittwater, probably 9-13yr olds. Not sure whether to say well done or not, but would have been "character building". I will say knowing both associations the kids would have been very safe.
I can't imagine that RPAYC would send 8 foot dinghies into Broken Bay. Pittwater at Newport seems a little more likely.
 

Snow Blowey

Old n' Crusty
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Flushing from the river system isn't wasted water, it benefits the health of that system. And it has benefits for that big salty pond too.

If you start with water with EC of 1500uS/cm and all of that water is replaced with fresh floodwater (lets say EC of 200uS/cm. Once everything is at 200uS/cm you are just replacing fresh water with fresh water.

Salinity in the system is the result of two things:

1 - Evaporation - take water out and the mass of salt stays the same so i finite volume of water will become saltier as water is lost to evaporation.

2 - Dissolution of salt in the earth. An infinite source.

So you can put as much fresh water down the river in one hit as you like. But you will never get below the salt concentration of the rainfall. Once the flood is over, remaining water will become salty with time due to the two reasons above. What is better, to get rid of all your fresh water at once? Or to have many river volumes in storage to supply later fresh flows when the rain dries up again?
 

warrie

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Rubbish. Menindee was always going to fill again when it started raining. In 2019 there was no natural flow anywhere in the Darling catchment. That includes above and below water storage.

Like i said at the time. It will rain again, major flood events will happen again. At those times there is plenty of water to flush the river, recharge groundwater and to be stored for later use (and for later release into the next dry period. When you let all the runoff flow out to sea unused you waste it.
The measure of a healthy environment would be the regular natural filling of Menindee Lakes, alas, the powers in charge are actively working towards Menindee Lakes being taken off line permanently.
Prior to about 1960 and the construction of the Menindee Lakes Scheme, the lakes were ephemeral and I suppose you could say had a natural inflow as there was little irrigation and extraction. Our forefathers sought to tame the Darling flow and put it to better use a la the Snowy Scheme. So weirs and diversion channels were built, Broken Hill set up a ski club and all was rosy for a few decades. A combination of regional drying and over extraction has led to the present predicament.
This La Nina is still delivering if not a bit too much on the coast but the next NW cloudband is set to wet the NW slopes etc onto an already saturated catchment. Gerg has a pic here to show the likely demand by off -river storage holders. Link: And his comment: To fill private off-stream water storages like these (dark blue, cotton-central of the 'Northern Basin', March last year). But many of those are already part-full; how much more water can they take? We simply do not know.
And how much will reach the Lakes?
 

warrie

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Not that we've had anything extraordinary here. Mostly light drizzle mixed in with some heavier showers, but certainly nothing news worthy. It's actually been very disappointing considering the forecasts. I was led to expect a much more intense event.
I think most of us sodden citizens have had enough intensity to date.
 

Untele-whippet

beard stroker
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Jul 13, 2006
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Great Western Highway blocked between Blackheath and Medlow Bath due to flooding. Particularly awesome as the road follows the crest of a ridge at that point!
Yeah, just checked out the building swamp site at Dargan, coming back the queue of cars was banking up to Mt Vic pub.
I think Bells Line of Rd is closed at North Richmond too.
No access to Sydney from the west.
 

Steve777

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Re the 1867 Hawkesbury Flood, there's a plaque on the wall of the Macquarie Arms hotel in Windsor, near the main street and above the Windsor Bridge, which shows the level of the 1867 flood: https://www.hawkesburyaustralia.com.au/info/things-to-see-and-do/windsor-walk/

I forget how far above the normal river level it was but it's a surprising height - from memory I'd guess about 15 metres.
 

robbo mcs

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Re the 1867 Hawkesbury Flood, there's a plaque on the wall of the Macquarie Arms hotel in Windsor, near the main street and above the Windsor Bridge, which shows the level of the 1867 flood: https://www.hawkesburyaustralia.com.au/info/things-to-see-and-do/windsor-walk/

I forget how far above the normal river level it was but it's a surprising height - from memory I'd guess about 15 metres.
19.7m was the peak height.

There are a few of those markers around. There used to be one at Mcgraths Hill, a couple of kilometres away from the river, and it was halfway up a telegraph pole:eek: Surrounded by hundreds of houses and businesses though:rolleyes:
 

derider

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I think most of us sodden citizens have had enough intensity to date.

I love intense rain events. I'm weird like that. Sadly, the Illawarra mostly misses out on the best ones these days. It usually drizzles when it's pouring down in other places. The last time I was fully satisfied was February last year. Now that was a proper event. Not this gloomy drizzle bullshit we usually get.
 
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