Two reservoirs are connected by three clean cast-iron pipes in series, $L_{1}=600 \mathrm{m}, \quad D_{1}=0.3 \mathrm{m}, \quad L_{2}=900 \mathrm{m}$
$D_{2}=0.4 \mathrm{m}, L_{3}=1500 \mathrm{m},$ and $D_{3}=0.45 \mathrm{m} .$ When the dis-
charge is $0.11 \mathrm{m}^{3} / \mathrm{s}$ of water at $15^{\circ} \mathrm{C}$, determine the difference in elevation between the reservoirs.