$2.(7$ points total$)$ A plan view of a confined aquifer is shown below $-$ i$.$e$.$ looking down from above. The aquifer extends $600$ m in the S$-$N direction and $2000$ m in the W $-$E direction. The boundaries on the north and south sides of the figure are no$-$flow and the boundaries along the west and east sides are constant head boundaries. The aquifer hydraulic properties change abruptly at the locations of the dashed lines at $600$ m and $\backslash (1,200\backslash$mathrm$\{$~m$\}\backslash ),$ with the transmissivity for each zone given in the figure. The head at A is $21\mathrm{.}00$ m and at F it is $12\mathrm{.}00$ m $.$

a$.$ Assuming steady flow through the aquifer, what are the heads at locations $\backslash ($ B$,$ C$,$ D $\backslash )$ and $\backslash ($ E $\backslash )?$ Find your answer, developing an exact computation $($i$.$e$.,$ mathematically derived$)$ by using principles of groundwater flow. $(3$ points$)$

b$.$ Using the mathematical result, calculate the total volume flow through the aquifer. $(1$ point$)$

c$.$ Using $3$ stream tubes, draw a flownet on the diagram that starts with square elements in the west. Complete the flownet by distorting the elements appropriately as you move to the East and finish the diagram. Once you have completed your flownet, calculate the head drop between each pair of equipotentials. $(2$ points$)$

d$.$ Using the flownet only, calculate the total volume flow through the aquifer. Hint: If you have drawn your flownet correctly, you should get the same answer as part b$.(1$ point$)$