Eli5: why can’t we have a transcontinental water pipeline for flood/drought?


Every year the east side of the country seems to have historic flooding, meanwhile there is always historic drought out west.

Why can’t we just build a pipeline to pump flood zones to drought zones?

In: 0

Economically the flood water is very spread out and there is no way to really pipe it away. It would be far easier to set up a desalination plant and have it pump water but even then the amount of water required would cost more than the drought land could produce.

Because the amlount of water to move is incredibly large.

You’d have to create a continent sized river rivaling the Mississippi to manage that.


We build pipelines for oil because oil sells for nearly $2 a gallon (~$.50 a liter). If you ever check your water bill, you’re paying a tiny fraction of that price, which means that pipeline water would be uncompetitive or unaffordable by the consumer. To make it competitive, that would need to be subsidized; at the rates that the average consumer uses water on a daily basis, the expense of that subsidy would be massive. It would be a very hard sell for any government to their people. Additionally, if you’re relying on floodwater as a source, it will be seasonally idle, meaning your huge investment is doing nothing for large chunks of the year.

This is ignoring the physical logistics of the challenge: multiple pipelines to meet demand, collection and pumping stations, water treatment facilities because water runoff isn’t immediately safe to drink.

We can build pipelines for water. There are two major issues, depending on the exact situation:

1. Flooding – Not feasible. If you are referring to pumping flood water away, the volume of water needing to be pumped is impossibly large and it is impossible to predict when it would be available to be pumped. Drought zones would need predictable supplies. Even if it could be pumped, the size of the storage tanks needed to hold that much water to make supplies of flood water available when needed would be on the scale of cities.
2. Fresh Water – Control and Access. If you are referring to simply being able to pump fresh water from areas that have it (like the Great Lakes areas) to drought areas), those areas that have water do not want to part with it. They realize how valuable a resource fresh water is. The states around the Great Lakes even have a formal agreement (the Great Lakes Water Compact – [https://dnr.wisconsin.gov/topic/WaterUse/Compact.html](https://dnr.wisconsin.gov/topic/WaterUse/Compact.html)) that governs how that resource is managed. Those states also have an international agreement with the provinces in Canada (the Great Lakes St. Lawrence River Basis Sustainable Water Resources Agreement – [https://www.ontario.ca/page/great-lakes-st-lawrence-river-basin-sustainable-water-resources-agreement-0](https://www.ontario.ca/page/great-lakes-st-lawrence-river-basin-sustainable-water-resources-agreement-0)) that border the Great Lakes for the same purpose.

You can do that, but the cost of building them would be very high. If you what to divert water from a flood you need pipes that have a size larger than natural rivers’ other waterways, they clearly do not have enough capacity to do it.

The amount of water that is missing in a drought is enormous. Look at for example Califonia where the dryest year had 9.4 inches of rain and the wettest 41.66 inches. The average is 22.9 inches. So the dryest year was 13.5 inches = 0.3429 meters less than the average

The area is of the state is 423,970 km2 so the missing water volume was 423970*0.3429*10^-3 = 145 cubic kilometers of water= 145 billion cubic meter= 38 trillion gallons

The average disagree of the Mississippi River is 16,800 cubic meters per second. So we need the average water flow in 8.6 million seconds = 99 days. So the missing amount of water is 27% of the water that flows through the Mississippi.

When you use them unless there is a drop in elevation you need to use a pump to move the water up in elevation. That is like running a hydroelectric power plant in reverse. It is done as a way to store energy in [https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity](https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity)

So there is a land with higher elevation in between you need tunnels. If the endpoint is higher up you need to pump up water.

For droughts this ignores the problem that there likely is not enough excess water available in other locations, you would need enormous dams to store water where extra is available to have enough to fix a drought.