$[15]2.$ A small$-$scale flow experiment is conducted in the box shown to scale in the Figure below with a model sheet pile wall A$\text{'}-$D$.$ Out$-$of$-$plane width of the model is $10$ cm $.$ Permeability $k$ of the soil is $0\mathrm{.}002c\frac{m}{s}.$

$($a$)$ Identify all equipotential EQ and flow line FL boundary conditions directly on the figure below.

$($b$)$ Using lines $1,2,3,$ and $4$ on the figure as flow lines, sketch the equipotential lines for a square flownet directly on the figure.

$($c$)$ Using your flownet, estimate the total volume of flow through the model in $5$ minutes, in $c{m}^3.$

$($d$)$ A standpipe is inserted at point $1,35$ cm below the upstream water level $A-A^{\text{'}}.$ Using the flow net shown, estimate the height of water in this standpipe below the upstream water level $A-A^{\text{'}}?$

$($e$)$ During the experiment, with water flowing, the downstream ground surface is altered to location F$-$G$.$ Indicate the revised equipotential boundary condition on the downstream side. Sketch likely revised flow line locations in the downstream region using dashed lines directly on the Figure.