4 ms·

Unfortunately this particular method of creating seafloor subsidence won't help because we'll be moving water from under the sediment layer over it, so the sea

by chr1 7y ago

Unfortunately this particular method of creating seafloor subsidence won't help because we'll be moving water from under the sediment layer over it, so the sea level should stay the same. I wonder however if moving water into aquifers of deserts would help.

schiffern 7y ago
Sadly the current economic incentives seem to reward removing water from aquifers. Obviously there's direct pumping, but moreso land use changes that stop groundwater infiltration: losing wetlands and forests to pavement, roofs, poorly-designed agricultural drainage, and even regularly-mowed grass which develops subsoil hardpan. Any would-be groundwater is diverted into flash flood runoff and overloaded storm sewer systems. The ultimate end to this poor land/hydrology management is desertification, where ~zero water is stored on the land and all water immediately drains off in a torrent.
mythrwy 7y ago
"Subsidence" means sinking. In this case, with the fresh water below removed (thus nothing holding it up) the sediment layer between salt and fresh would sink (or subside). At least that's what happens on land. With the weight of the salt water on top, the effect may be even larger. But likely we won't be pumping out enough water to make a measurable difference so it's not a "real" suggestion.
- chr1 7y ago
  After removing the water and using it, the water will come back into ocean so sinking (or subsiding:) of the sediment layer won't change the water level. The same water that was under the sediment layer will simply move above it. So there won't be any effect independently from the amount of pumping.
  - mythrwy 7y ago
    Ah ok, I see your point. But (and getting even more ridiculous here) the water need not necessarily be returned to the ocean. It could be used for instance to water crops inland or recharge inland aquifers that had previously been depleted.
    - chr1 7y ago
      Yes, i think moving water to inland aquifers and dry lake-beds in current deserts should have a significant impact, but unfortunately i have not been able to find a study confirming or disproving this.
      - foobar1962 7y ago
        Australia has huge problems with salinity, where previously dry areas were deforested and irrigated with water sourced from other areas (like the Murrumbidgee Irrigation Area). Saline groundwater rises to the surface and causes the top soil to become irreversibly salty. Re-forestation would solve the problem (deep rooted plants lower the groundwater level) but because the soil is salty, nothing can or will grow there. The areas are now wastelands, good only for salt mining. I remember some research was put into developing salt-tolerant trees specifically to solve the problem, not sure how successful it was.

by chr1 7y ago

schiffern 7y ago

Sadly the current economic incentives seem to reward removing water from aquifers. Obviously there's direct pumping, but moreso land use changes that stop groundwater infiltration: losing wetlands and forests to pavement, roofs, poorly-designed agricultural drainage, and even regularly-mowed grass which develops subsoil hardpan. Any would-be groundwater is diverted into flash flood runoff and overloaded storm sewer systems. The ultimate end to this poor land/hydrology management is desertification, where ~zero water is stored on the land and all water immediately drains off in a torrent.

mythrwy 7y ago

"Subsidence" means sinking. In this case, with the fresh water below removed (thus nothing holding it up) the sediment layer between salt and fresh would sink (or subside). At least that's what happens on land. With the weight of the salt water on top, the effect may be even larger. But likely we won't be pumping out enough water to make a measurable difference so it's not a "real" suggestion.

chr1 7y ago
After removing the water and using it, the water will come back into ocean so sinking (or subsiding:) of the sediment layer won't change the water level. The same water that was under the sediment layer will simply move above it. So there won't be any effect independently from the amount of pumping.
- mythrwy 7y ago
  Ah ok, I see your point. But (and getting even more ridiculous here) the water need not necessarily be returned to the ocean. It could be used for instance to water crops inland or recharge inland aquifers that had previously been depleted.
  - chr1 7y ago
    Yes, i think moving water to inland aquifers and dry lake-beds in current deserts should have a significant impact, but unfortunately i have not been able to find a study confirming or disproving this.
    - foobar1962 7y ago
      Australia has huge problems with salinity, where previously dry areas were deforested and irrigated with water sourced from other areas (like the Murrumbidgee Irrigation Area). Saline groundwater rises to the surface and causes the top soil to become irreversibly salty. Re-forestation would solve the problem (deep rooted plants lower the groundwater level) but because the soil is salty, nothing can or will grow there. The areas are now wastelands, good only for salt mining. I remember some research was put into developing salt-tolerant trees specifically to solve the problem, not sure how successful it was.