10.6.2 Surveying

On large slides where access to the slope is hazardous and there is a need to make frequent and precise measurements and rapidly analyse the results, surveying is the most suitable  monitoring method. There are three components of a survey system.


  1. One or several reference points on stable ground, which can be viewed from the instrument stations closer to the slide.
  2. A number of instrument stations set up on reasonably stable ground at locations from which the slide is visible. If the co-ordinate positions of the movement stations are to be measured, then the instrument stations should be arranged such that they form an approximately equilateral triangle.
  3. A series of stations set up just outside the slide area, located relative to the instrument stations. It is preferable that the measurement direction be in the likely direction of movement so that the distance readings approximate the actual slide movements.


Figure 13: Survey system to remotely measure slope movement