$(a)$ Locate and name the water reservoirs in Figures $(a)$ and $(b)$.
$(b)$ Which has an advantage over the other and why?

(N/A) The water reservoir in Figure $(a)$ is a surface water body (pond/lake),and in Figure $(b)$,it is an underground water body (aquifer).
$(b)$ Figure $(b)$ has an advantage over Figure $(a)$. The advantages of storing water underground are:
$1$. It does not evaporate.
$2$. It spreads out to recharge wells and provides moisture for vegetation over a wide area.
$3$. It is protected from contamination by human and animal wastes.
$4$. It prevents the breeding of insects like mosquitoes.