Node 0
(origin)
Node 2
Lake 6
Node 5
Node 8
Lake 5
Node 7
Lake 4
Node 6
Lake 1
Node 3
Lake 3
Node 4
Lake 2
Node 1
Edge 1
Edge 2
Edge 5
Edge 7
Edge 8
Edge 6
Edge 4
Edge 3
a
b
Fig. 7.11 Construction of
AEM variables. (a) River
network; (b) the seven
corresponding AEM
variables produced by
function aem() (Redrawn
after Legendre and
Legendre 2012)
7.4 Eigenvector-Based Spatial Variables and Spatial Modelling
351