Team 52849 MCM/ICM Page 6 of 31
tegration representing current drinking water cannot be changed, so the relevant equation becomes:
drinkingw ater = personallyfilteredwater + transpor tedwater
.
Using the rates from the network-system above, we get:
drinkingwater = r ∗ e ∗ A + t ∗ P
,
where r is personal filtration rate, e is personal filtration efficiency, A is available water, t is trans-
portation rate, and P is potable water. Further substituting the integrated rates from the model,
we get the following summary of the most relevant drivers of drinking water scarcity:
drinkingwater = r ∗ e ∗ A + t ∗ (f ∗ A + d ∗ E − c)
,
where f is filtration rate of available water, d is donation rate, E is external water, and c is loss to
corruption.
3.1.3 Sensitivity: Comparing Scarcity-Driver Effects
This base equation allows us to determine the most effective interventions, based on two simple
principles.
1) Increases in variables that are multiplied by fractions dampens the effect of the increase:
(x) ∗
1
n
− > (x + c) ∗
1
n
= x ∗
1
n
+ c ∗
1
n
2) Increases in variables that are multiplied by numbers greater than 1 amplifies the effect of
the increase, which is further amplified based on the magnitude of the value:
(x) ∗ N− > (x + c) ∗ N = x ∗ N + c ∗ N
3.1.4 Solution Comparison Based on Yield Ratios
In order of highest yield/change ratio, interventions include:
1) Increase transportation of potable water to homes (ex: Pipes)
The systems variable with the greatest change in drinking water per small changes in magnitude
is t, since it is amplified by P (which is in turn amplified by A and E)and not mitigated by any
fractional rates. Moreover, as Haiti’s pipe situation is already known to be in shambles, modest
increases in pipe access would significantly change the total transportation of water, further am-
plifying this effect.
2) Increase filtration of available water (ex: In-Situ Wells)
The filtration f is amplified by both t and A, so the second best intervention is to increase filtra-
tion of available water to drive up potable water rates. The only caveat here is that if corruption
were to rise in the future such that c > f ∗ A + d ∗ E, this intervention would be ineffective as the
filtered water would never reach the general populace.
3)Increase prevalence and efficiency of personal filters (ex: LifeStraws)
For r and e, a small change results in a high change in yield magnitude due to the largeness of A.
Changing filter efficiency may take a while on the scientific side, but spreading access to personal
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