A lot of California’s valley is sinking. It’s due to groundwater, or actually, the lack of groundwater. Since 1925, many areas have actually sank by as much as 30 feet. The actual surface – the ground, has gone towards the center of the earth by 30 feet.
While on the surface we’re out of the drought, sort of, but there’s still a drought under the ground. All the years, and this goes back a hundred or more years, of digging wells deeper and deeper, trying to find more groundwater, is causing the ground to sink. When you pump all that water out of the ground, space is left, and it gets filled with the surrounding dirt. Eventually, enough space is filled that 30 feet worth of elevation drops. Another problem of the dropping elevation is the risk of flooding – lower elevations flood more, and an area that may not have flooded 40 or 50 years ago can now be low enough to cause a problem.
In the 70s, the aqueducts were built, designed to carry water from the mountains to southern California. Now those aqueducts are starting to fail, crack, and shift, because the ground is ever changing underneath them. Even some bridges that cross the duct have sank down with the ground, and are now getting hit with water when the duct if flowing near full capacity. Another possible problem is that the aqueducts are keeping the water which would naturally soak into the ground from actually getting into the ground to replenish underground springs. That’s only IF the springs can be refilled, since when the ground sinks it also compacts and fills the space where water would have normally gone.
Teams are using measuring tools on the ground, attached to airplanes, and even orbiting the earth, to determine which areas are sinking the most, or where they should focus on making necessary repairs or improvements to the aqueducts, roads, bridges, and levees.