Patent ID: 8621922

Claim:
A method of monitoring subsidence and/or rising of a waterbottom, the method comprising: arranging a plurality of pressure sensors in the interior and at different points along the length of a sealed pressure resistant protective tube, which tube is filled with a fluid and provided with valves which are configured to divide the interior of the sealed pressure resistant protective tube into a series of sealed longitudinally spaced segments; lowering the tube onto the waterbottom while the valves are closed and divide the interior of the tube into a series of longitudinally spaced segments; opening the valves after installation of the tube on the waterbottom while the fluid pressure in the interior the tube is substantially lower than the hydrostatic pressure of the water surrounding the tube; and deducing any subsidence and/or rising of the waterbottom from any variation of the fluid pressures measured by the pressure sensors at different moments in time.