Water Stewardship

How to Calculate Flood Levels & Depths

Having determined the geodetic ground elevation, flood levels and depths can be calculated as follows.

  1. Scale the distance from the desired location
    to the upstream flood level isogram (x).

  2. Scale the distance between the flood level isograms
    located upstream and downstream of the desired location (y).

  3. Subtract the downstream flood level from the upstream level (z).

  4. Calculate the flood level.
    Flood Level = Upstream Flood Level - {(x/y)z}

  5. Calculate flood depth
    Flood Depth = Flood Level - Ground Elevation*
    *Determined by ground survey