New research reveals why some rivers in the San Joaquin Valley are causing the ground to uplift when others aren’t. The answer lies beneath the ground’s surface. A new study from scientists at Stanford University combines satellite data with airborne electromagnetic (AEM) flight data to see exactly what’s happening with recharged water from the Sierra Nevadas.  The satellite process, called interferometric synthetic aperture radar (InSAR,) bounces signals onto the ground which can read over time where ground has uplifted due to groundwater recharge. The data, from the wet year of 2017, shows water traveling through the valley underground uplifting the surface as it moves.  But other areas didn’t see the same effect. The study points out two sites where there are natural waterways, one near Fresno and one near Visalia. The Fresno site didn’t see any uplift while the Visalia site did. … They found that only areas with significant clay saw uplift. If the ground is made up of too much coarse material, like sand and gravel, the water sinks in fast but simply moves through it and doesn’t uplift.