Data Flow Overview

This is the flow of "logical" data needed for predicting the lahar. For an exhaustive list of the inputs and outputs as well as available switches, see Program Options. For more detail on how the data files are formatted, see Data Formats.

Stream Finder

• Input:
  • DEM
• Calculation:
  • Use 8-direction slope comparison (starting from edges and working inward) to find flow direction for each cell.
  • Count the number of cells that flow into each cell to get the flow total grid.
• Output:
  • Simplified DEM with sinkholes filled + Metadata file
  • Flow direction grid
  • Flow total grid

Inundation Zone Mapper

• Input:
  • Simplified DEM + Metadata file
  • Flow direction grid
  • Flow total grid
  • Stream threshold
  • Starting point X and Y
  • Volume of the anticipated lahar in cubic meters (may be multiple, to generate multiple predictions in the same area) (Must support values of at least 10^12 -- you will need a longlong to store it)
• Calculation:
  • A = 0.05 V ^ (2/3) - to determine the cross sectional area of the lahar (Following a stream, use this with the topography to determine width of the flow)
  • B = 200 V ^ (2/3) - to determine the total planimetric area of the lahar. (This tells you how far you go before you stop.)
• Output:
  • Inundation zone maps (One for each Volume input)

Plotter (the GUI)

The plotter is outside of the "logical" part of the calculation, but it handles some extra data that just aids the user in selecting their inputs.

• Input:
  • Visual layers -- additional data layers that get overlaid on the hillshade like glacier locations and zone markings, to help the user select a starting point.
• Internal:
  • Slider for the stream threshold that updates the display instantly.