TABLE $2.$ Soil Properties

W$50$ denotes Wagner $50$; OTT, Ottawa; W$18,$ Wagner $18$; WM$1$

Wagner mix $1$ ; WM$2,$ Wagner mix $2$; and WM$3,$ Wagner mix $3.$

we discussed how we approximate the relationship between the capillary pressure and

the residual saturation with relationships from van Genuchten and Brooks and Corey. Several

researchers measured the capillary pressure$-$saturation curves for six soil and sediment samples

r$4$r$3$r$2$r$1$

P$=1$atm

gravity

r$4=$r$3*3$

r$3$

r$2=$r$3*4$

r$1=$r$3*2$

and fit both the van Genuchten and the Brooks and Corey models to the data $($See Table $4$

below$).$ Using the van Genuchten parameters given in this table, plot the capillary pressure$-$

saturation curves for drainage for all six samples on the same plot. Now plot the capillary

pressure$-$saturation curves for wetting for all six samples on the same plot.

b$)$ Based on the drainage curves, what sample$($s$)$ do you expect to have the largest pore size, the

smallest pore size, the widest distribution of pore sizes, the narrowest distribution of pore sizes?

How do your expectations compare to the mean grain size and the grain uniformity index of the

different samples presented in Table $2$ above, why?