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Engaging Data has a nice data display for this. It more clearly shows the capacities of the individual reservoirs [1]. They also have displays for the current s

Engaging Data has a nice data display for this. It more clearly shows the capacities of the individual reservoirs [1]. They also have displays for the current snowpack [2] and rainfall [3]. After a very slow start, this year's precipitation is finally up to the median. If you want to understand why California has so much trouble with water, pay special attention to the rainfall totals web page. It shows how many years got N inches of rainfall. Best year was more than 200% of median rainfall, and worst was 40% of median. And it is historically common to have many sub-median years in a row. [1] https://engaging-data.com/ca-reservoir-dashboard/ https://engaging-data.com/ca-reservoir-dashboard/ [2] https://engaging-data.com/california-snowpack-levels/ https://engaging-data.com/california-snowpack-levels/ [3] https://engaging-data.com/california-precipitation-levels/ https://engaging-data.com/california-precipitation-levels/

KennyBlanken 3y ago
This hides one major component, however: ground compaction. When you draw down the water table, the ground compacts, and the capacity is never regained, which means you now have far less capacity in the aquifer for a particular area. It will only get worse in overdeveloped areas or areas that overdraw their water for agriculture and industry.
- yawgmoth 3y ago
  Do we have measurement of that? How worse does it get on overdraw?
  - dylan604 3y ago
    there have been articles/posts with showing just how much the ground has compacted or sunk. "overpumping caused land in the state's San Joaquin Valley to sink almost 3 feet (85 centimeters) during a recent drought from 2007 to 2010." [0] "USGS Scientists Explain How Aquifer Compaction is Measured" [1] [0] https://www.jpl.nasa.gov/news/overpumping-reduces-californias-groundwater-storage https://www.jpl.nasa.gov/news/overpumping-reduces-california... [1] https://www.usgs.gov/centers/california-water-science-center/usgs-scientists-explain-how-aquifer-compaction-measured https://www.usgs.gov/centers/california-water-science-center...
  - FuriouslyAdrift 3y ago
    "Further inland in California’s Central Valley, excessive pumping of groundwater for agriculture has caused the land to sink significantly. Since the 1920s, sections of the San Joaquin Valley have sunk by as much as 8.5 meters (28 feet). Groundwater pumping becomes even more problematic during droughts, exacerbating subsidence problems. Data from 2015 showed some spots subsided at rates as high as 600 millimeters (2 feet) per year." https://www.washingtonpost.com/climate-environment/2023/05/30/land-sinking-us-subsidence-sea-level/ https://www.washingtonpost.com/climate-environment/2023/05/3...
  - quickthrowman 3y ago
    https://www.usgs.gov/media/images/location-maximum-land-subsidence-us-levels-1925-and-1977 https://www.usgs.gov/media/images/location-maximum-land-subs... Keep in mind this picture was taken 47 years ago
- sugarkjube 3y ago
  interesting view - as environmentalist around here are promoting initiatives to reduce use of concrete etc to allow more water in the ground -> that would be useless then ? > When you draw down the water table, the ground compacts, and the capacity is never regained, which means you now have far less capacity in the aquifer for a particular area. Now that i think it over, if you're not suppose to use it (the capacity below water table) due to compaction, that capacity is useless, so it doesn't matter if it disappers ?
  - randomsolutions 3y ago
    Porous concrete has been useless. It clogs up eventually and loss it's ability to transport water. The groundwater disappearing is a problem if you build up ag/industry/development based on the groundwater availability and then lose that source of water with no economical alternative.
    - b112 3y ago
      It also seems crazy in certain areas, such as where the ground freezes in winter. All those little pores will freeze and break, turning the entire concrete mass to powder. People hate unneeded work, so in the old days, if there were large boulders of granite in fields to clear, they'd hand drill holes in the top. Then, over a few winters, the freezing water would break the granite.
      - Retric 3y ago
        It's less of a problem than you would think as water that's liquid will drain through it and snow etc doesn't expand. You generally get pot holes because water pools in an a layer and then expands and contracts, but if it's draining that's not a problem. Also, air entrainment has long been (~1930's) used as a means of freeze thaw resistance because it allows some deformation without cracking. Porous concrete has similar flexibility.
        hedora 3y ago
- scoofy 3y ago
  Also damns slowly fill with silt over their finite lifespans. When the orriville dam is past it’s useful life, there is little alternative for central CA.

KennyBlanken 3y ago

This hides one major component, however: ground compaction. When you draw down the water table, the ground compacts, and the capacity is never regained, which means you now have far less capacity in the aquifer for a particular area. It will only get worse in overdeveloped areas or areas that overdraw their water for agriculture and industry.

yawgmoth 3y ago
Do we have measurement of that? How worse does it get on overdraw?
- dylan604 3y ago
  there have been articles/posts with showing just how much the ground has compacted or sunk. "overpumping caused land in the state's San Joaquin Valley to sink almost 3 feet (85 centimeters) during a recent drought from 2007 to 2010." [0] "USGS Scientists Explain How Aquifer Compaction is Measured" [1] [0] https://www.jpl.nasa.gov/news/overpumping-reduces-californias-groundwater-storage https://www.jpl.nasa.gov/news/overpumping-reduces-california... [1] https://www.usgs.gov/centers/california-water-science-center/usgs-scientists-explain-how-aquifer-compaction-measured https://www.usgs.gov/centers/california-water-science-center...
- FuriouslyAdrift 3y ago
  "Further inland in California’s Central Valley, excessive pumping of groundwater for agriculture has caused the land to sink significantly. Since the 1920s, sections of the San Joaquin Valley have sunk by as much as 8.5 meters (28 feet). Groundwater pumping becomes even more problematic during droughts, exacerbating subsidence problems. Data from 2015 showed some spots subsided at rates as high as 600 millimeters (2 feet) per year." https://www.washingtonpost.com/climate-environment/2023/05/30/land-sinking-us-subsidence-sea-level/ https://www.washingtonpost.com/climate-environment/2023/05/3...
- quickthrowman 3y ago
  https://www.usgs.gov/media/images/location-maximum-land-subsidence-us-levels-1925-and-1977 https://www.usgs.gov/media/images/location-maximum-land-subs... Keep in mind this picture was taken 47 years ago
sugarkjube 3y ago
interesting view - as environmentalist around here are promoting initiatives to reduce use of concrete etc to allow more water in the ground -> that would be useless then ? > When you draw down the water table, the ground compacts, and the capacity is never regained, which means you now have far less capacity in the aquifer for a particular area. Now that i think it over, if you're not suppose to use it (the capacity below water table) due to compaction, that capacity is useless, so it doesn't matter if it disappers ?
- randomsolutions 3y ago
  Porous concrete has been useless. It clogs up eventually and loss it's ability to transport water. The groundwater disappearing is a problem if you build up ag/industry/development based on the groundwater availability and then lose that source of water with no economical alternative.
  - b112 3y ago
    It also seems crazy in certain areas, such as where the ground freezes in winter. All those little pores will freeze and break, turning the entire concrete mass to powder. People hate unneeded work, so in the old days, if there were large boulders of granite in fields to clear, they'd hand drill holes in the top. Then, over a few winters, the freezing water would break the granite.
    - Retric 3y ago
      It's less of a problem than you would think as water that's liquid will drain through it and snow etc doesn't expand. You generally get pot holes because water pools in an a layer and then expands and contracts, but if it's draining that's not a problem. Also, air entrainment has long been (~1930's) used as a means of freeze thaw resistance because it allows some deformation without cracking. Porous concrete has similar flexibility.
      - hedora 3y ago
scoofy 3y ago
Also damns slowly fill with silt over their finite lifespans. When the orriville dam is past it’s useful life, there is little alternative for central CA.