Question $2(40\%)$:

The top of a $20m$ thick aquifer is $50m$ below surface. The soil above the aquifer has an

average porosity of $0\mathrm{.}35$ and a bulk dry density of $1700k\frac{g}{m^3}.$

a$)$ What is the pressure and pressure head at the top of the aquifer under hydrostatic

conditions $($i$.$e$.,$ no$-$flow conditions$)?(6\%)$

b$)$ What is the total vertical stress and effective stress at the top of the aquifer under

hydrostatic conditions $($units in $Pa$ or $\frac{N}{m^2})?(8\%)$

c$)$ A well in the aquifer is now pumping and the head drops $5m$ in the aquifer. If the

compressibility of the aquifer is ${10}^{-7}P{a}^{-1},$ compressibility of water is $4\mathrm{.}4{10}^{-10}P{a}^{-1},$

and porosity of the aquifer is $0\mathrm{.}4$ :

determine how much water comes out of one $m^3$ of the aquifer due to soil

compression $(5\%)$

determine how much water comes out of one $m^3$ of the aquifer due to water

expansion $(5\%)$

comment on the relative amounts from $1)$ and $2)(5\%)$

Determine specific storage of the aquifer $(5\%)$

if the well influences a $0\mathrm{.}5k{m}^2$ area, how much water will be removed from

storage in the aquifer? $(6\%)$