5 ms·

TLDRV They divert the rainy season water to natural aquifers and hope it reappears down river in the dry season. The small scale of the effort currently makes

TLDRV They divert the rainy season water to natural aquifers and hope it reappears down river in the dry season. The small scale of the effort currently makes me a little skeptical that it's achieving anything. Underground water is impossible to measure. What might be more effective and certainly more measurable would be to build a dam/reservoir.

abdullahkhalids 5y ago
The linked paper > Infiltrated water is retained for an average of 45 d before resurfacing, confirming the system’s ability to contribute to dry-season flows. We estimate that upscaling the system to the source-water areas of the city of Lima can potentially delay 99 × 106 m3 yr−1 of streamflow and increase dry-season flows by 7.5% on average, which may provide a critical complement to conventional engineering solutions for water security. https://www.nature.com/articles/s41893-019-0307-1 https://www.nature.com/articles/s41893-019-0307-1
- gus_massa 5y ago
  I can't see the paper, but there is some interesting technical details in the supplementary data https://static-content.springer.com/esm/art%3A10.1038%2Fs41893-019-0307-1/MediaObjects/41893_2019_307_MOESM1_ESM.pdf https://static-content.springer.com/esm/art%3A10.1038%2Fs418... In page 15, table 2 they show that they put some Eosin https://en.wikipedia.org/wiki/Eosin https://en.wikipedia.org/wiki/Eosin upstream before the water entered the earth, and then they collected water from the springs downstream a few weeks later and measure how much Eosin was there, and used this to estimate how long the water was stored.
  - abdullahkhalids 5y ago
    I didn't have time to read the paper, but here is the pdf http://mural.maynoothuniversity.ie/13800/1/SG_geog_potential.pdf http://mural.maynoothuniversity.ie/13800/1/SG_geog_potential...
  - qubidt 5y ago
    FYI: https://unpaywall.org/ https://unpaywall.org/
ralfn 5y ago
Thank you so much. The article is just too polluted with pseudo intellectual nonsense, but water management is a very underappreciated discipline of engineering. Although it seems impossible to measure how much water is stored in the deep soil, it is often possible to notice if it runs out. We had that last summer in the Netherlands. I suppose knowing we reached zero, and knowing the influx (mm rain, and the flow of the Rhine), and then also knowing the outflow means you can make a some sound estimate. However, that requires a high density of weather stations and tooling at the influx and outputs. It's not something you can just do through some regulation targeted at the water company. You'll need a specific branch of the government, since messing with water affects everyone, from erosion to trade, to agriculture to climate (the presence of water makes the climate a more mild climate) In the Netherlands, this is all done by an independent water government, a democracy older than our democracy itself. It even predates notions of citizenship.
- wolverine876 5y ago
  > The article is just too polluted with pseudo intellectual nonsense Always an ironic comment!
  - hinkley 5y ago
    Projection ain't just a river in Egypt. Wait... that doesn't sound right.
  - ralfn 5y ago
    I wasn't aware I was trying to sound intellectual. I'll go find a doctor. That was definitely not my intention.
- hinkley 5y ago
  I don't know what I was watching but someone mentioned and then drew a diagram showing that a well may be at a certain depth, to comfortably reach water, but the water level will drop as soon as you start pumping because the water has to move horizontally through the rock, and so you will get a gradient between 'water level' in the aquifer and water level at your well, and the faster you pump the higher the slope. I guess there are some ways to work out permeability and volume based on how the levels at one well are affected by activity at the next well.
dpierce9 5y ago
Article woo aside, underground water is not impossible to measure. Min well depth (or depth of dry wells) is a straightforward way to measure the aquifer level for a small area. It doesn’t tell you much but it tells you something. Combine with your neighbors taking the same measurement over time and you have a good data set. That is before you get to things like ‘geology’ which are known factors shaping underground water supplies. Further, if water goes into a pit, you can measure or estimate how much is going in. If you can measure the shape of the pit you know how much is there. If you know surface area at a given level and temp/environmental conditions you can estimate evaporation. So you can say: X vol went in, Y evaporated, and Z is how much we now think is ground water based on current depth and evaporation (excluding animals and humans drinking). It is much harder to associate the pit activity with a given well and obviously the scale here may be below the precision of any of the estimators.
- hinkley 5y ago
  I learned that it's fairly routine in wetland restoration work to sink shallow 'wells' (stand pipes) a couple feet down to measure water table levels over the course of a year or so. Wetlands - and in particular the plants that are adapted to them - can be permanent or seasonal, and can change over a 20 foot distance, so knowing which you have and where can be the difference between a failed or successful restoration.
IncRnd 5y ago
> TLDRV They divert the rainy season water to natural aquifers and hope it reappears down river in the dry season. Simple diversion of water is not what was discussed. Thank you for the summation, but you summarized the non-relevant information. > The small scale of the effort currently makes me a little skeptical that it's achieving anything. Underground water is impossible to measure. Even if you are not familiar with how vegetation works, there is proof contained later in the article. They discuss how removing portions of peat land caused the surrounding plants to dry out and die.

abdullahkhalids 5y ago

The linked paper > Infiltrated water is retained for an average of 45 d before resurfacing, confirming the system’s ability to contribute to dry-season flows. We estimate that upscaling the system to the source-water areas of the city of Lima can potentially delay 99 × 106 m3 yr−1 of streamflow and increase dry-season flows by 7.5% on average, which may provide a critical complement to conventional engineering solutions for water security. https://www.nature.com/articles/s41893-019-0307-1 https://www.nature.com/articles/s41893-019-0307-1

gus_massa 5y ago
I can't see the paper, but there is some interesting technical details in the supplementary data https://static-content.springer.com/esm/art%3A10.1038%2Fs41893-019-0307-1/MediaObjects/41893_2019_307_MOESM1_ESM.pdf https://static-content.springer.com/esm/art%3A10.1038%2Fs418... In page 15, table 2 they show that they put some Eosin https://en.wikipedia.org/wiki/Eosin https://en.wikipedia.org/wiki/Eosin upstream before the water entered the earth, and then they collected water from the springs downstream a few weeks later and measure how much Eosin was there, and used this to estimate how long the water was stored.
- abdullahkhalids 5y ago
  I didn't have time to read the paper, but here is the pdf http://mural.maynoothuniversity.ie/13800/1/SG_geog_potential.pdf http://mural.maynoothuniversity.ie/13800/1/SG_geog_potential...
- qubidt 5y ago
  FYI: https://unpaywall.org/ https://unpaywall.org/

ralfn 5y ago

Thank you so much. The article is just too polluted with pseudo intellectual nonsense, but water management is a very underappreciated discipline of engineering. Although it seems impossible to measure how much water is stored in the deep soil, it is often possible to notice if it runs out. We had that last summer in the Netherlands. I suppose knowing we reached zero, and knowing the influx (mm rain, and the flow of the Rhine), and then also knowing the outflow means you can make a some sound estimate. However, that requires a high density of weather stations and tooling at the influx and outputs. It's not something you can just do through some regulation targeted at the water company. You'll need a specific branch of the government, since messing with water affects everyone, from erosion to trade, to agriculture to climate (the presence of water makes the climate a more mild climate) In the Netherlands, this is all done by an independent water government, a democracy older than our democracy itself. It even predates notions of citizenship.

wolverine876 5y ago
> The article is just too polluted with pseudo intellectual nonsense Always an ironic comment!
- hinkley 5y ago
  Projection ain't just a river in Egypt. Wait... that doesn't sound right.
- ralfn 5y ago
  I wasn't aware I was trying to sound intellectual. I'll go find a doctor. That was definitely not my intention.
hinkley 5y ago
I don't know what I was watching but someone mentioned and then drew a diagram showing that a well may be at a certain depth, to comfortably reach water, but the water level will drop as soon as you start pumping because the water has to move horizontally through the rock, and so you will get a gradient between 'water level' in the aquifer and water level at your well, and the faster you pump the higher the slope. I guess there are some ways to work out permeability and volume based on how the levels at one well are affected by activity at the next well.

dpierce9 5y ago

Article woo aside, underground water is not impossible to measure. Min well depth (or depth of dry wells) is a straightforward way to measure the aquifer level for a small area. It doesn’t tell you much but it tells you something. Combine with your neighbors taking the same measurement over time and you have a good data set. That is before you get to things like ‘geology’ which are known factors shaping underground water supplies. Further, if water goes into a pit, you can measure or estimate how much is going in. If you can measure the shape of the pit you know how much is there. If you know surface area at a given level and temp/environmental conditions you can estimate evaporation. So you can say: X vol went in, Y evaporated, and Z is how much we now think is ground water based on current depth and evaporation (excluding animals and humans drinking). It is much harder to associate the pit activity with a given well and obviously the scale here may be below the precision of any of the estimators.

hinkley 5y ago
I learned that it's fairly routine in wetland restoration work to sink shallow 'wells' (stand pipes) a couple feet down to measure water table levels over the course of a year or so. Wetlands - and in particular the plants that are adapted to them - can be permanent or seasonal, and can change over a 20 foot distance, so knowing which you have and where can be the difference between a failed or successful restoration.

IncRnd 5y ago

> TLDRV They divert the rainy season water to natural aquifers and hope it reappears down river in the dry season. Simple diversion of water is not what was discussed. Thank you for the summation, but you summarized the non-relevant information. > The small scale of the effort currently makes me a little skeptical that it's achieving anything. Underground water is impossible to measure. Even if you are not familiar with how vegetation works, there is proof contained later in the article. They discuss how removing portions of peat land caused the surrounding plants to dry out and die.