Measuring porosity in flume experiments with a sand bed

  1. After completing a flume experiment, carefully drain the flume of just enough water so that water surface is at the sand bed.
  2. Collect (say with a short PVC pipe) a section of sand.
  3. Measure the mass of this section (=mwet)
  4. Put sample into oven to cook off all water.
  5. Measure the mass of the dry sample (=mdry)
  6. Given knowledge of sand density (=rhosand) and water density (=rhowater), then porosity (lambda) can be computed as:

lambda = 1/((mdry*rhowater)/((mwet-mdry)*rhosand)+1)