![](bg8.png)
matic drivers are nodes 12 (erosion increase) and 14
(basins degradation, Cutzamala). Both of them are
turned on due to social drivers.
The results found in section 3.2 reconfirm that so-
cial drivers have a high influence over the network.
By analyzing the hidden patterns obtained by keep-
ing the different drivers ON, the difference were in
the following nodes: waste waters discharge increase
(7), vegetal cover loss (8), degradation in the water
quality (10), erosion increase (12) and basins degra-
dation, Cutzamala (14). That were activated by the
social drivers and not by the climatic drivers.
In section 3.3 the system was forced under two
different climate change scenarios. The considera-
tions made were the decrease and the increase in PCP.
The resulting vector in comparison with the vector v
3
obtained in the case (a) in section 3.2,(base scenario,
that we obtained when nodes 1 and 2 were forced in
section 3.2), differed only on the nodes 11, 12 and
14, and there was no difference when we considered
a PCP decrease or increase. This is a consequence of
the particular structure of the system.
When considering weighted edges for the whole
system (section 3.5) we validated the results obtained
in previous sections. Since the difference between
social and climatic factors was in nodes 12 (erosion
increase) and in 14 (basins degradation, Cuzamala)
once again. In section 3.4 we could identify that, even
though the system behavior was sensible to changes in
the weights, it maintained the general tendency.
In section 3.6 we found that the “causality” that
climate and social drivers (as a whole) imparted over
the decrease in water availability was ”high”. But in
both cases the “high” causality is centered on a par-
ticular processes.
From these results we can conclude, first of all,
that the system is significantly affected by climatic an
social drivers, i.e. both can trigger the system and lead
it into an undesirable state. Moreover, it appears that
the strength of social drivers are greater than those of
the climatic drivers. Since the social drivers in Mex-
ico city are currently on, climatic drivers will act as an
accelerator for the degradation processes on the water
system. Therefore both drivers should be taken into
account for policies design.
The general recommendations after the analysis
are focused on two branches:
Climatic drivers:
I
1→18
(1, 20, 16, 18) = min{H, H, H} = H.
Social drivers:
I
3→18
(3, 9, 13, 16, 18) = min{H, H, H, H}.
Which have a “high” influence over water availabil-
ity. Further investigation is needed for each node and
edge on the two branches, to design policies and so-
lutions.
A general conclusion based on this FCM for wa-
ter availability in Mexico city, is that the degradation
process will occur, given the present conditions, with
climatic drivers or without them, as social drivers are
more influential on the network. The social situation
that operates over the water system is pushing the sys-
tem into an undesirable state, and only with a more in
depth study of the interactions among the nodes we
will know whether or not the system can return to its
equilibrium state.
It is remarkable that the system’s dynamic did not
change wether a consideration of an increase or a de-
crease in precipitation was made. It is also notable
how the system is sensible to changes in the weight of
the edges but without changing its general tendency.
ACKNOWLEDGEMENTS
The present work was developed with the support of
the Programa de Investigaci
´
on en Cambio Clim
´
atico
(PINCC) of the Universidad Nacional Aut
´
onoma de
M
´
exico (UNAM).
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