Eq. (20) shows that for minimizing water consumption, the
ratio of head loss to gross head (hLþ ¼ hL/Hg) should not exceed
15.6%. The 15.6% ratio also provides the threshold for the optimal
penstock diameter. Losses higher than 15.6% mean that a small
penstock diameter is used. The 15.6% ratio is about half of that
derived for maximum power and maximum flow discharge,
which is 33.3%. This means that the optimal conditions for producing power do not correspond to those that use maximum flow
discharge for a given