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Floods and droughts


studiot
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On 8/1/2022 at 6:49 PM, studiot said:

It was not my intention to limit examples and discussions to the US experience.

A scatter gun from Australia.

We have reasonably reliable (though that may be changing) monsoon rains in the north. We also have regular flooding in Queensland (north east state) where rains fall on the west side of the Great Divide (main mountain range running more or less north south inside the coast) and there is basically no falls for rivers/ Hence "the channel country". I remember one year where the town of Nyngan (NSW) was in drought. Then finally the flood waters reached and Nyngan was in Flood. Two weeks later back to drought as the floods moved on.

One attempt to collect the monsoons was the Old River scheme (Western Australia in the north) which has so far proven too remote from the rest of the country for farm productivity to overcome transport cost. Infrastructure and not just the dams themselves but the transport - pipes, pumps etc, is a commercial issue for sure.

In Sydney there is a desalination system with little to do other than during heavy drought. I often wondered why keep running it and pipe over the Blue Mountains (that Great Divide again) into the Turon River. It isn't that far. 200 - 250km? That is an early tributary to the Murray, huge water resource problems and travels all the way through Australia to discharge into the southern Ocean near Adelaide in South Australia. It costs a fortune to have the de-sal in stand by, just keep it running. 

Here in Brisbane or more accurately SEQ (South East Queensland) they have connected the productive dams in the Gold Coast and Sunshine Coast (south and north) to the main but largely non-productive damn in the Brisbane Valley. They can then shunt water from where it lands to where it doesn't. But that is nothing like as bold or expensive as connecting to the the northern monsoon.

 

 

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On 8/27/2022 at 4:11 AM, druS said:

In Sydney there is a desalination system with little to do other than during heavy drought. I often wondered why keep running it and pipe over the Blue Mountains (that Great Divide again) into the Turon River. It isn't that far. 200 - 250km?

Unfortunately, the economics would be horrendous. Pipelines are very expensive, and rarely make economic sense, even for oil which is thousands of times as valuable as water. And piping up and over a mountain would involve huge technical challenges and costs compared to on the flat, both in construction, and energy costs powering the pumps to lift the water upwards. And desalination plants only produce a small quantity, compared to rivers. So from a cost and engineering point of view, it would be a complete non-starter.

Water is so heavy that lifting it requires a hell of a lot of energy. That's why we can extract so much electricity from the reverse process of letting it fall in hydro-electric schemes. Sending water up a mountain is the reverse of that.

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4 hours ago, mistermack said:

Unfortunately, the economics would be horrendous. Pipelines are very expensive, and rarely make economic sense, even for oil which is thousands of times as valuable as water. And piping up and over a mountain would involve huge technical challenges and costs compared to on the flat, both in construction, and energy costs powering the pumps to lift the water upwards. And desalination plants only produce a small quantity, compared to rivers. So from a cost and engineering point of view, it would be a complete non-starter.

Water is so heavy that lifting it requires a hell of a lot of energy. That's why we can extract so much electricity from the reverse process of letting it fall in hydro-electric schemes. Sending water up a mountain is the reverse of that.

 

These mountains are not exactly "alpine". From recollection I'm guessing 800'? The horizontal difference is next to nothing compared to the continental requirements to connect the monsoon to highly populated areas. Which is many thousands of km. If the local suggestion is silly, then the rest is inane. Which is really why I was saying.

In regards de-sal - they also swallow a lot of energy to simply sit idle. 

In terms of hydro, in Australia the water can not simply be lost. So that huge energy you gain flushing the water through is than countered by the energy to pump the water back again, with the obvious system losses in the overall energy equation. So clearly a net loss. But if you pump off peak, and run the hydro in peak it is a form of battery. The efficiency of that does seem challengeable, but it is how hydro works here. Well in the Snowy scheme, not sure whether they simply lose the water in Tasmania.

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1 hour ago, druS said:

 

These mountains are not exactly "alpine". From recollection I'm guessing 800'? The horizontal difference is next to nothing compared to the continental requirements to connect the monsoon to highly populated areas. Which is many thousands of km. If the local suggestion is silly, then the rest is inane. Which is really why I was saying.

In regards de-sal - they also swallow a lot of energy to simply sit idle. 

In terms of hydro, in Australia the water can not simply be lost. So that huge energy you gain flushing the water through is than countered by the energy to pump the water back again, with the obvious system losses in the overall energy equation. So clearly a net loss. But if you pump off peak, and run the hydro in peak it is a form of battery. The efficiency of that does seem challengeable, but it is how hydro works here. Well in the Snowy scheme, not sure whether they simply lose the water in Tasmania.

Thanks for your continued interest and more considered responses than the previous responder's wild posting.

You mentioned rive gradients, I don't know if there are equivalent maps for Australia but here are some figures for the British Isles.

riverslopes.jpg.ae8cb0a3c8b07157923321b102c64c3f.jpg

There are some key comments in your post notably

1 hour ago, druS said:

in Australia the water can not simply be lost.

That is so true almost everywhere.

+1

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Apologies, I got ruminating. This post is linger than it should be. I'm going to leave it all the same.

Studiot, I lived in England for 10 years. It amazed me how little water storage there seemed to be and how water was so easily available. Obviously current circumstances are challenging my conception. From recollection after 2 weeks with no rain there were hose bans. Wow.

Still.

I select the Darling River as an example here, as it starts sort of, from the same sort of location (but south) as the "Channel Country". As I understand it, the Darling runs for roughly 1500 km long starting at an altitude of roughly 120m. What is that? A little less than 1cm per km? Certainly not measured in m per km. That's a running river system. Channel Country is north of that, flatter. Some of the water works it's way and peters out in the Strzlecki (Desert) but some, occasionally makes it's way into Cooper Creek. Roughly once in every 4 years there is enough water in the Cooper to travel to Lake Eyre (Kati Thundra). Roughly once in every 12 years the lake fills. The lake is very slightly below sea level when full so it actually picks up these drainage scenarios from all surrounding States. This water does not make it's way to the ocean.

But the water is travelling through basically flat land, no fall. There are patches of wetlands where the drains settle. These require regular topping up, and won't let the water travel further until full. And basically all of this is in desert.

As I understand it, the palaeontologists read the recent history of Australia much like modern day Savannah of Africa. Annual heavy rain falls with megafauna migrations chasing the water movement across the nation. But the land got drier, the mega fauna failed, the rain became unreliable. Except on the coast and in the north. 

As an unscientific observation - flooding of the Eyre seems to happen more often now than it did when I was a child. Conversely we are seeing fires now that match the mythical horrific fires of early settlement - every few years and much more widespread.

Shunting the water around seems completely sensible but it is costly. It is starting to happen regionally across the areas that surround the major (coastal) cities. Beyond that seem beyond the capability of the nation. 

***

I know that that use of links here is sometimes problematic. Hopefully this is acceptable. Paul Lockyer was in front of the camera, Bean and Tynehurst accompanied him. They document the travel of the water from channel to Lake, and died when their helicopter crashed. In 2009. The flooding of the Lake has happened at least twice since, possibly three - more frequent now. The link is public TV the Aus version of BBC. you probably have to register to watch. it's worth it. 

https://iview.abc.net.au/show/lake-eyre/video/NS1544H001S00

While the flooding is more frequent, don't think this means that the country is no longer desert. I crossed the Simpson (Desert) in 2018 over the Warburton (it has a confluence with the Cooper I think). Recent rain meant the Warburton was green. Crazy, as this was in the drought that was continuous up to our recent massive fire storm season in Australia. I could tell when we were out of farms (cattle property) into the desert proper. No greening but there were noticeably more twigs and vegetative husks in the desert.

 

Edit: checking out the Wikipedia page for Lake Eyre I see that the Warburton does not confluence with the Cooper, but is a continuation of the Diamantina. Wow. And I see that the famed Barcoo does run into the Cooper. It might amuse you to consider that as an interested and investigative Aussie I didn't know this, even when I have travelled through those areas. Mostly it's not in flood, certainly not when I am travelling, and you really just don't notice a dry river with no fall. It's just grassland and cattle.

Edited by druS
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3 hours ago, druS said:

These mountains are not exactly "alpine". From recollection I'm guessing 800'? The horizontal difference is next to nothing compared to the continental requirements to connect the monsoon to highly populated areas. Which is many thousands of km. If the local suggestion is silly, then the rest is inane. Which is really why I was saying.

That 800 feet would take a hell of a lot of energy to get past. Niagara Falls are about 170 feet high on average, but look at the power in the water when it drops. 

The river Thames only drops 360 feet, from source to the sea. You could recoup some of the energy, on the other side of the mountain, with a hydro-electric plant, but that would be and expensive installation, for a tiny gain. The output of a desalination plant is tiny, compared to a river. 

3 hours ago, druS said:

In regards de-sal - they also swallow a lot of energy to simply sit idle. 

Do you have a link for that? I can't find that stated anywhere, and I'm struggling to see why, when the main energy input is powering very high pressure pumps. If the pumps are off, where is the energy being used? 

In any case, if it's not worth turning the desalination plant off, there would surely be a market for the excess water genrated by keeping it running. 

It could be used locally for agriculture and industry, surely a more economic use that pumping it miles away over mountains. 

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On 7/30/2022 at 9:45 PM, studiot said:

As I read about droughts in California and Texas, but floods in Kentucky I wonder if the obvious engineering commonsense reaction will pertain.

We need more water collection, storage and distribution facilities compared to the past.

Will politix ever permit the obvious engineering solution ?

Fair point if you were considering say the 100 miles or so unpumped supply of Manchester via Thirlmere aqueduct.

But for more continental scale issues, I think it's probably the wrong question.

On 8/11/2022 at 3:27 AM, zapatos said:

To me the obvious engineering solution involves the movement of people from areas of too little water to areas where there is plenty of water.

+1

There must come a point where further development of parched lands is simply unsustainable due.

 

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2 hours ago, sethoflagos said:

There must come a point where further development of parched lands is simply unsustainable due.

On 8/11/2022 at 3:27 AM, zapatos said:

To me the obvious engineering solution involves the movement of people from areas of too little water to areas where there is plenty of water.

 

So should we all move to Antarctica or Greenland ?

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57 minutes ago, zapatos said:

Are Antarctica and Greenland the only places that have plenty of water?

I don't know, I'm just following your logic to its conclusion.

 

It's not as simple as you make out.

 

Yes, I suspect some migration is inevitable.

But equally overcrowding in other areas of plentiful to too much water has led to trajedy as todays floods in Pakistan demonstrate.

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I remember years ago, there was constant talk of flooding in Bangladesh. The cause was given as deforestation in the Himalayas due to firewood collection and over grazing. 

The water isn't held up long enough to soak in to the soil, and the soil itself gets washed down the rivers, making the run-off even more rapid. 

Pakistan has some of the highest mountains in the world, so chances are, something similar might be happening now. 

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2 hours ago, studiot said:

I don't know, I'm just following your logic to its conclusion.

 

I don't see how my logic leads to everyone moving to Antarctica and Greenland.

Using that line of reasoning, we could say that your proposal means that we are going to distribute water equally throughout all the world's deserts, which I'm sure is not what you were suggesting.

My proposal was simply a counter to your proposal that engineering is the way we should be addressing areas of the world where there is not enough water to sustain human activity. It is a lot easier to create zoning codes to disallow fountains, farms, and golf courses in the desert than it is to engineer shipping a finite water supply across the desert just because it is asked for.

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21 minutes ago, mistermack said:

I remember years ago, there was constant talk of flooding in Bangladesh. The cause was given as deforestation in the Himalayas due to firewood collection and over grazing. 

The water isn't held up long enough to soak in to the soil, and the soil itself gets washed down the rivers, making the run-off even more rapid. 

Pakistan has some of the highest mountains in the world, so chances are, something similar might be happening now. 

On tonight's news it was reported that low lying Sindh province in the Indus delta has received 8 times its annual average rainfall during July2022 to August 2022.

That doesn't sound like tree chopping in the Himalaya to me.

 

9 minutes ago, zapatos said:

I don't see how my logic leads to everyone moving to Antarctica and Greenland.

Using that line of reasoning, we could say that your proposal means that we are going to distribute water equally throughout all the world's deserts, which I'm sure is not what you were suggesting.

My proposal was simply a counter to your proposal that engineering is the way we should be addressing areas of the world where there is not enough water to sustain human activity. It is a lot easier to create zoning codes to disallow fountains, farms, and golf courses in the desert than it is to engineer shipping a finite water supply across the desert just because it is asked for.

You proposed it as a single point solution.

I have accepted that there will be a measure of this solution.

And yes I was exaggerating for effect, just as you did.

:)

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I suspect the most viable solutions will involve conservation of water and evaporative loss reduction.  Xeriscaping, drip irrigation, cover materials on reservoirs, etc.  I doubt "shipping" water up grades will ever be economic, unless it's Perrier. 

Similarly, floodwater has a way of defeating large-scale engineering.  Discouraging development of lowlands and subsidizing the move of populations to higher ground will probably be more economic than endless levee and seawall building.  Too many people, through no fault of their own, live on lowlands that should have stayed as marsh and wetlands purifying water naturally and dampening storm surges.  

Good posts, very thought provoking, sorry to be late to the party.

 

 

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29 minutes ago, TheVat said:

Similarly, floodwater has a way of defeating large-scale engineering.  Discouraging development of lowlands and subsidizing the move of populations to higher ground will probably be more economic than endless levee and seawall building.  Too many people, through no fault of their own, live on lowlands that should have stayed as marsh and wetlands purifying water naturally and dampening storm surges.

You know this as an Engineer I suppose ?

Have you tried discussing this with a dutchman ?

29 minutes ago, TheVat said:

I suspect the most viable solutions will involve conservation of water and evaporative loss reduction.  Xeriscaping, drip irrigation, cover materials on reservoirs, etc.

 

Definitely my point about Yeomans, the Harappans and the beavers.

 

 

Edited by studiot
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33 minutes ago, studiot said:

On tonight's news it was reported that low lying Sindh province in the Indus delta has received 8 times its annual average rainfall during July2022 to August 2022.

I know, I saw that. But Sindh is pretty dry in normal years. Manchester gets five times as much rain in an average year. Flooding rarely results from rainfall on flat land like Sindh. Here in Gloucester, we get plenty of rain, but the floods come down from Wales. The Indus Gorge is the highest gorge in the world, and you get a lot of snow melt this time of year, along with monsoon rains falling on the mountains. If Sindh got a lot of rain, then the mountains would have got a load as well.

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3 minutes ago, mistermack said:

I know, I saw that. But Sindh is pretty dry in normal years. Manchester gets five times as much rain in an average year. Flooding rarely results from rainfall on flat land like Sindh. Here in Gloucester, we get plenty of rain, but the floods come down from Wales. The Indus Gorge is the highest gorge in the world, and you get a lot of snow melt this time of year, along with monsoon rains falling on the mountains. If Sindh got a lot of rain, then the mountains would have got a load as well.

Last time the Indus delta flooded the guardian wrote

Quote
5 Oct 2010 · Decades of building irrigation and hydro-electric dams further up the Indus drained the river of its force, allowing salty fresh water to ...

 

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15 hours ago, studiot said:

You know this as an Engineer I suppose ?

Have you tried discussing this with a dutchman ?

 

 

I did not say ALL water diversions are doomed to fail - I was basing the comment on the many catastrophic failures (especially riparian containment) in the US, where specs were overly optimistic about nature's good behavior.   My opinion is mainly informed by observation and living, myself, through two floods.  America has had an intense obsession with progress and rapid development that often leads to political machinery that ignores warnings from cooler heads.  

Many water experts here are currently making the case for moving some communities to higher ground as the less costly option.  

 

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1 hour ago, TheVat said:

I did not say ALL water diversions are doomed to fail - I was basing the comment on the many catastrophic failures (especially riparian containment) in the US, where specs were overly optimistic about nature's good behavior.   My opinion is mainly informed by observation and living, myself, through two floods.  America has had an intense obsession with progress and rapid development that often leads to political machinery that ignores warnings from cooler heads.  

Many water experts here are currently making the case for moving some communities to higher ground as the less costly option.  

 

Thank you for your clarification. +1

Of course you have plenty of higher ground in America.
How much do you think the Dutch have ?

I take your point about the headlong rush for progress in America, youngsters were ever that way inclined.

This Mississippi system (we used to have spelling contests at primary school as to who could spell 'Mississippi' backwards the fastest) includes some of the longest waterways in the world and the Midwest has plenty of potential space to hold back water for dry years and save the stretch from St Louis to New Orleans from repeat serious flooding.

The river in my local town empties into the channel with the second highest tide in the world.
Historically when there is a combination of spring high tides, adverse westerly winds and additional rainfall in the catchment area there have been floods in the town centre.
The new country park provides enough low lying holding area and a brand new parkland, unusual in the 20th century, for the forseeable future protection needs.

It can be done, it has been done, economically and beneficially. It just requires the political will.

Edited by studiot
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On 7/30/2022 at 1:45 PM, studiot said:

As I read about droughts in California and Texas, but floods in Kentucky I wonder if the obvious engineering commonsense reaction will pertain.

We need more water collection, storage and distribution facilities compared to the past.

Will politix ever permit the obvious engineering solution ?

Maybe there are places in the world where you may predict, according to climate change, that will likely have EXCESS water in the future, and other areas that will likely have a water SHORTAGE in the future, that are not too far separated, that water could be transported from one area to the other using mostly gravity, but also a few water pumps to get the water over humps.  I was thinking of half pipes to transport the water with a thin cover.  My question is, since I live in Southern California, could water be transported from the wet north to the dry south?  My water cost is only one penny per gallon.  When will my water utility start taxing my water usage in order to build future infrastructure (as well as maintain the current infrastructure) to save or channel water?

Edited by Airbrush
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1 minute ago, Airbrush said:

Maybe there are places in the world where you may predict, according to climate change, that will likely have EXCESS water in the future, and other areas that have a water SHORTAGE, that are not too far separated, that water could be transported from one area to the other using mostly gravity, but also a few water pumps to get the water over humps.  I was thinking of half pipes to transport the water with a thin cover.  My question is, since I live in Southern California, could water be transported from the wet north to the dry south?

The Romans built hundreds of miles of canals and aqueducts in the country that gave birth to modern California.

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  • CharonY changed the title to Floods and droughts
  • 2 weeks later...
On 8/30/2022 at 5:18 PM, studiot said:

The Romans built hundreds of miles of canals and aqueducts in the country that gave birth to modern California.

They did, and it's impressive. But you can do a lot with slave labour in every link of the supply chain. And of course, it's always downhill, no pumping involved as far as I know. There were matching impressive waterworks in the Andes, by the Incas I think (from memory) and of course they had the advantage of melting glaciers at very high altitudes, so they always had a decent fall to work with. 

On the OP idea, I would think that one of the most suitable spots to do it would be from the upper Mississippi and Missouri to the drier parts of Kansas and Oklahoma. If it's not economic there, then it's probably not economical anywhere else. The land is flat but the gradient is uphill for a long way.

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