Charvak Dam, Uzbekistan
The Charvak Dam is a 770m wide, 168m high embankment dam on the Chirchiq River in Uzbekistan and is one of the largest hydropower plants in Central Asia. Water levels in the reservoir can vary as much as 40m seasonally between winter (low) and summer (high).
The changes in water levels create an enormous pressure on the dam wall and we can see it moving, very slightly, using satellite observations. In this case study, we used two-years’ worth of free Sentinel-1 satellite data, gather from ascending and descending orbits, to monitor the up-down and east-west motion of the dam wall. Using the APSIS© method, we were able to get full coverage of pixels over the earthwork wall and the resulting survey is shown in an animation below.
Parts of the wall sway very clearly by about 4cm between maximum and minimum, towards the lake (blue) as it empties and away from the lake (red) as it fill, in the east-west (EW) part of the figure. There is also some seasonal motion in the up-down (UD) direction, possibly also due to loading.
This type of motion is common for dams subject to large seasonal variations in water level. With the APSIS© method Terra Motion can guarantee complete coverage over any large structure and, with free data from the Sentinel-1 mission, low-cost monitoring can be assured for the foreseeable future.