Exercise 25
Suppose a mass of 1000 mg is introduce in the center of a large tank of sand in a hydrogeology laboratory with uniform, one-dimensional, flow moving through the tank. The hydraulic conductivity is 0.1 cm/sec, effective porosity is 0.2, the dispersivity in the x direction is 5 cm, dispersivity in the y direction is 1/5 of the dispersivity in the x direction, dispersivity in the z direction is 1/10 of the dispersivity in the x direction, and the head drop across the 100 cm long tank is 10 cm.
What will the concentration be at:
(a) 25 cm after 1000sec?
(b) the center of mass of the plume after 1000sec?
(c) a point that is 10 cm to the left and 5 cm below the center of mass of the plume after 1000sec?
- Why is the concentration at 25 cm from the source so different for Exercise 24 part (a) and this exercise part (a)?
- Would you expect measurements of concentrations in plumes in a field setting to produce the values you calculated? Why, or why not?