Subsidence is often not completely reversible, but groundwater recovery can stop the problem and even cause the surface to rebound a little. This was part of the story in 39 percent of the cases studied, including places like Shanghai, Bangkok and Houston.
Land subsidence schedules in 15 of the cases studied.
So how could groundwater reclamation be a problem? Some examples could simply be classified as “too much of a good thing”: flooding of tunnels or particularly low-lying areas and farmland. But there were also structural problems as previously dry sediments became saturated and the land surface moved upward. Some seismically active areas have even struggled with increased risk of liquefaction during earthquakes.
On the other hand, chemistry can cause problems. For example, surface contaminants and fertilizers have been mobilized as the water table has risen to reach them. And evaporation from flooded farmland has caused salts to gradually accumulate in the soil in parts of Türkiye and Iran.
the plane
Jasechko identified several lessons when comparing all of these cases. First, most included at least two of the three common approaches he identified. Problems with complex causes require multiple solutions.
Another lesson is that the amount of time it took to see groundwater trends change direction varied quite a bit. In some cases, the water level data showed results within a few years, but in others it took decades. Bangkok began instituting fees for groundwater use in the late 1970s, for example, but it took more than 20 years before the fees rose enough to have an impact. And then there’s climate variability: Periods of wet or dry years can obscure the results of your actions.
Another lesson is that details matter. There may be areas where rising groundwater above a certain level causes problems, and it would be better to identify these in advance rather than through experience. And since each situation is unique, the best approach in each individual case will be a unique set of solutions.
At a fundamental level, this study reminds us that groundwater recovery has happenedso it is possible for communities to change things. So when we learn from history, we can find some parts that we would really like to repeat.
Science, 2026. DOI: 10.1126/science.adu1370 (About DOIs).
