Table 2

. Types of 3D model and their characteristics.

Type of 3D modelOverviewSystematicDetailed
Cross-section spacingSeveral km0.5-1.5 km< 500 m
Cross-section lengthTens of km5-10 km< 5 km
Density of (coded) boreholes< 1 per km2Commonly 5-20 per km2Often hundreds per km2
Stratigraphical levelMajor Groups and Formations onlyFormations and Members; big lensesMembers and thin individual beds and lenses; artificial ground
Modelling speed (excluding data preparation)Up to hundreds of km2 per day2-10 km2 per day< 2 km2 per day
ScaleCompatible with 1:625000 and 1:50000 geological lineworkCompatible with 1:25000 and 1:10000 geological lineworkCompatible with detailed site plans at scales as large as 1:1000
Minimum unit thickness2 m1 m0.1 m
Modelling outputOften only sections and an open fence diagramComputation of surfaces for export to GISComputation of surfaces and lenses for export to GIS
UsesEducation, visualization and overviews (for example, general catchment characterization), first-pass assessmentsBuilds a 3D model stack for interrogation in site selection, route planning, resource assessment, recharge and aquifer studies etc.Detailed 3D model for analysis of thickness, volumes, flow paths providing bed-by-bed stratigraphy for use in urban planning, site investigation and development