  We find that different geographical structures of networks lead to varied
percolation thresholds, although these networks may have similar abstract
topological structures. Thus, the strategies for enhancing robustness and
immunization of a geographical network are proposed. Using the generating
function formalism, we obtain the explicit form of the percolation threshold
$q_{c}$ for networks containing arbitrary order cycles. For 3-cycles, the
dependence of $q_c$ on the clustering coefficients is ascertained. The analysis
substantiates the validity of the strategies with an analytical evidence.
