Elevation and Surface Modelling

Historically elevation data was collected through field surveys and later through stereo photogrammetric measurement using overlapping aerial photographs. The output was recorded as iso lines on maps with a constant equidistance (elevation difference between lines). In Denmark, our earliest national elevation data sets date back to ca 1870

List of land surface parameters derived from the Digital Elevation Model.

  • Slope aspect: Direction of the steepest slope gradient from the North
  • TWI : Calculates the slope gradient and specific catchment area based TWI.
    TWI = ln (As/tan β) : where As is the upslope catchment area and β is the slope gradient (Moore et al., 1993)
  • Direct Sunlight Insolation (1 yr) : Calculates potential incoming solar radiation (insolation) calculated n SAGA GIS (Böhner and Antonić, 2009)
  • Elevation : Lidar produced an elevation of the land surface
  • Flow Accumulation: Number of upslope cells
  • Mid-Slope Position : Covers the warmer zones of slopes (Bendix, 2004)
  • MRVBF: Identifies the depositional areas (Gallant and Dowling, 2003)
  • SAGA Wetness Index: Same as TWI but uses modified catchment area instead (Böhner et al., 2001)
  • Slope gradient : Maximum rate of change between cells and neighbours.
  • Slope-length factor: Calculates the slope length as used by the Universal Soil Loss Equation (Desmet and Govers, 1996)
  • Vertical distance to channel network: Calculated vertical distance to the nearest channel for each cell
  • Valley depth: Relative position of the valley