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In-Depth Information
this decline presents unique “scaling down” challenges for the city's infrastructure: a
system designed for a citizenry of over a million people quickly came to support less
than six hundred thousand.
Our stream chemistry researchers have mixed feelings regarding this transformation.
On the one hand, urban ecologies are of great interest to them: the effects of “coupled
systems” (natural and human changes) is precisely what they seek to study. On the other
hand, such large-scale interventions present a virtually uncountable number of variables
to manage in their studies: population, demographics for that population, policy and
legal interventions leading to engineering overhauls, and of course innumerable changes
to the sewage system itself. For some, entire trajectories of investigation had to be
scrapped. For others this presented a natural experimental condition: “This, for us, was
a great experimental opportunity because we had seven years of background data off
these twelve streams and a few of them were very strongly affected by the sewage
improvements and a few of them were not.”
Considered as an “experiment,” the new sewage system provided a unique occasion
for a novel study that no other researcher has had the ability to enact. Long-term data
stretching before and after a change will open a window of understanding on urban
renewal. Many cities in America and around the world are going through a similar
process. But, how are these new data to be reconciled as a single longitudinal arc? Scores
of variables that were well understood are thrown into a complex flux—making envi-
ronmental claims difficult for those scientists to assert.
Instruments: Breakdown and Automation
In a longitudinal study instruments come to be part of the field sites themselves. At
each of the sixteen sites, meter sticks are strategically placed in the streams. These sticks
are dug into the ground on metal poles or affixed to the walls of overpasses. These allow
for quick and standardized gauges of the height of the water flow, on each occasion
measured from the same location. However, water flows are not static—by their very
nature they continuously dig away at their own streambeds. As one scientist noted:
“Sometimes our poles stop being in the water at all. That's when we realize that our
readings might have been off for some time. That's a pain: we'll have to adjust recent
data, and figure out where to put the gauge meters next.”
Local residents are sources of consternation, as they interfere with instruments,
sometimes in ways that make it difficult to know this even happened. Each site has a
rain meter—a small open pipe that fills with rainwater—providing a measurement of
