A GNSS-GIS approach for high-resolution topographic mapping and resource assessment of a Mesozoic limestone quarry in Unaizah province, Saudi Arabia

Abstract

Topography is a decisive parameter usually taken into account during mining investigation and exploration process, particularly in shallow material reserve estimation within open pit mines or quarries. Consequently, obtained results and proposed exploration strategies and mining planning will substantially be dependent on used data quality. A workflow leading to high-resolution topographic mapping and accurate reserve estimation based on global navigation satellite system (GNSS) techniques and GIS, combined with data assessment and adjustment procedures is thereby proposed. The tested site belongs a mining industrial complex (several open pits) in the central province of Saudi Arabia. GNSS post-processing kinematic (PPK) was the conducted technique with controlled implementation of a ground reference station or GCP allowing post-processing operation. This latter was performed by the least-squares method and a suggested solution based on both single baselines and multi-baselines adjustment procedures. Data accuracy was thus maximized and sub-centimetric precision was yielded with a well-adjusted observation. A sub-metric grid-cell DEM was therefore produced by kriging interpolation of processed GNSS points, and high-resolution topographic maps were also extracted. DEM Error model has been analyzed using statistical parameters and residual cartography. Furthermore, non-extracted volume and the mass of limestone rocks into the investigated mining site were carried out using spatial gridding approach. In fact, spatial distribution of volumetric values was obtained and analyzed by considering the chosen topographic level for mining exploration and material extraction. In addition, a 2D block-mass estimation was readily conducted showing distribution of potential mass of the limestone rocks within the gridded surface of the tested site. Several 2D profiling were therefore extracted and used as additional and valuable tools for mining planning and extraction scenarios.