Method for determining the plan view coordinates and height of the working benchmark on a landslide with forced inclinations of the pole from the plumb position

Determination of plan view coordinates and working benchmarks heights on a landslide by linear-angular measurements using electronic total stations by the polar notching method and trigonometric levelling involves installing a prism reflector on a tripod or a pole plumb above the observed benchmark. In order to put it in the mentioned position, round levels are used, its accuracy affects precise determining the plan view coordinates and the benchmark heights. Direct visibility from the reference benchmark to the working one may be lost due to landslide displacements, reappeared vegetation or other obstacles. These circumstances may cause incomplete or distorted interpretation of the landslide hazard forecast during cyclic multi-year observations. The authors propose a new method of determining the plan view coordinates and height of the working benchmark on a landslide by linear-angular measurements on a pole with a prism reflector with its forced inclinations from the plumb position. The required data is calculated as the said parameters of the sphere center, which is constructed by approximation of those of the prism reflector node point obtained by tilting the pole. A number of experiments were carried out to confirm the performance of the method in geodetic landslide observations and its suitability for use in cases of visibility loss to the benchmark at the plumb position of the pole