DataGrapher: Walk-Through Guide

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The Data Grapher is a set of online tools that allow users to create customized graphs and tables of a whole variety of time-series data that are served up by the U.S. Geological Survey. Now, if you've never been here before, it probably would be helpful to check out the Help system. Under the Help menu, there are a number of tutorials and example graphs. Under Example Graphs, you can kind of get a sense for the types of graphs that can be made with the Data Grapher system. These are time-series graphs of a couple different parameters, or comparing time series among different sites-- two or three sites, showing repeating patterns over years, making color maps, and so forth. So, that's a good place to start...
 

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Image Dimensions: 640 x 360

Date Taken:

Length: 00:15:06

Location Taken: OR, US

Transcript

The Data Grapher is a set of online tools that
allow users to create customized graphs and tables

of a whole variety of time-series data that
are served up by the U.S. Geological Survey.

Now, if you've never been here before,

it probably would be helpful
to check out the Help system.

Under the Help menu, there are a
number of tutorials and example graphs.

Under Example Graphs, you can kind of
get a sense for the types of graphs

that can be made with the Data Grapher system.

These are time-series graphs of
a couple different parameters,

or comparing time series among
different sites-- two or three sites,

showing repeating patterns over years,

making color maps, and so forth.
So, that's a good place to start.

The other thing you can do under the Help menu

is to check out the video
tutorials that have been set up.

These tutorials show you how to
use the navigation menu up here.

They also tell you how to
make up your first graph,

and after you've made that graph,
how you can make adjustments to it.

So why don't we start with the one-site Data
Grapher, to visualize some time-series data.

Now, the steps required in each of
these various programs are very similar,

and you start by choosing a river basin.

In the Oregon Data Grapher, we
have about 20 river basins set up

because we're trying to manage about
a thousand different time series

from almost 300 different sites.

It's easier to choose the site of interest
if you first choose a river basin.

So let's choose the Tualatin
River in northwestern Oregon.

If you do that, then you limit your search
to only about a couple of dozen sites.

We're going to choose the
Tualatin River at Oswego Dam.

Once you've chosen a site, it shows you the
parameters that are available at that site,

and the starting and ending dates
for the data that are available.

Next, you simply have to choose the type of graph,
either a time-series graph or an X-Y plot.

For this example, we'll choose a time series.

Then you choose the types of parameters you want
to plot, so let's just choose dissolved oxygen

and we'll choose oxygen percent saturation.

Now, this is a good place to mention that you
have the ability to choose a daily statistic.

So, for example, if you're
interested in the daily minimum

dissolved oxygen concentration,
you can choose that,

and you can apply a running average.

Now, in this particular case, for oxygen
there's also this kind of odd option

to not allow supersaturation. In this case, if
we were to check all of these various things,

we would end up with the 7-day
running average of the daily minimum,

with no credit for supersaturation,
and that exactly corresponds

to one of the water-quality
standards in this particular river.

The Data Grapher is nice because
you can actually create statistics

that correspond to water-quality standards.

For now, though, let's turn these options off.

After you've chosen the parameters,
you need to choose a date.

Let's choose the entire year of, say, 2011.

You can see that for this site, we
have over twenty years of data set up

and available for you to explore.

But, let's just choose January
through December of 2011

and then you say "Make Graph"

and the results follow.

On the results screen, it kind
of summarizes your inputs,

gives you a couple of notes, and
then shows you the graphical result.

In this case, this is a time-series
graph of dissolved oxygen in blue

and oxygen percent saturation
in red, on the right-hand scale,

against an X axis of the date for an entire year.

From the results screen, you can
do a number of different things

if you scroll down towards the bottom.

You can either download the
data used to create this graph.

You can look at some inventory tables to show
you the amount of data that is available.

You can download the graph in
a variety of different formats;

so if you wanted to make
a PDF, you can do that.

You can also rescale the graph
by entering different axis limits

for the parameters that you're plotting.

Or, you can rechoose the
time limits for this site.

So, if we were to plot, for example,
only the data for June of 2011,

we would simply reselect those dates,

check "Replot"

and the result would be
shown for just June.

Here, we've zeroed in from a
year all the way down to a month,

and we can see very clearly the daily
variations in some of these data.

If we wanted this plot in a PDF
format, say we were happy with it,

we would just choose that
format and click "Download"

and up pops

our PDF.

It's pretty convenient.

One of the nice things that you
can do with the Data Grapher

is that you can compare data from among sites.

So, let's return back to the main menu

and let's choose a time-series
option for two different sites.

Using this, let's build a graph

that compares water temperature
at a couple of different sites.

Just to keep things easy, let's
stay in the Tualatin River basin.

We'll keep the Oswego Diversion
Dam as one of our sites,

and for our second site, let's choose a
site that's a little farther upstream.

Once we have that, we'll just choose
water temperaure for the two parameters,

and let's go ahead and choose July

and August

of 2011 for our comparison.

And, choose "Make Graph."

As you can see, the result pretty clearly
shows a comparison of water temperature

from two different sites
in the same river basin,

showing that the
downstream site in blue

is a little bit warmer during the summer
because it has had a chance to warm up.

This is a nice way to compare sites
upstream and downstream of each other

as well as sites in different river basins

to see whether the patterns match each other,

both for consistency of the comparison

and just to see how the different
rivers might behave a little differently.

Another way to use the Data Grapher that is
pretty useful is to look at patterns over time,

and one of the ways to do that is
to choose the By Year/Month option.

You can compare data from
many years on the same axis.

For this, let's choose a site
in the McKenzie River basin

that's downstream of a dam where
they've changed the operations.

Let's choose the South Fork McKenzie River near
Rainbow, which is downstream of Cougar Dam.

We'll just look at water temperature;

in this case, let's
choose the daily maximum

with a 7-day running average because
that's the water-quality standard that's used.

Let's include

most of the years--
so let's start in 2001

and go through 2011.

Let's look at a full calendar year,

and make a graph.

The results are going to show us

that there's been a bit of a
change in the pattern of the annual

water temperature over the years.

This line down here at the bottom
shows the first year on the plot, 2001,

before any operations at the dam were changed.

In 2002 through 2004, the reservoir
was drawn down behind the dam,

and you can see that they had some temperatures
that were a little warmer in September.

But, then they changed operations in
2005 after a major construction project,

and they've been able to create more of a natural
seasonal temperature pattern since that time.

This sort of graph allows you to show

data with repeating patterns over
a particular type of time period,

which can be done either for the
entire year or for specific months.

Another way to visualize

repeating patterns in the data

is to look at a color map.

From the menu under Time
Series, let's choose Color Maps,

and let's choose a site in
the Clackamas River basin.

We'll take a site down near the mouth
at Oregon City, and let's choose pH

because I happen to know that
that shows some nice patterns.

Let's choose an entire calendar year in 2010.

So, we just choose our dates--

make sure this goes from
January through December.

We want to plot the date on the X axis
and the hour of day on the Y axis,

and we have to choose a color scale.

You have many different
color scales to choose from,

and I'm just going to choose this kind
of standard blue-to-red color scale.

It's very easy to reverse that, if you wish.

Lower pHs on this color scale are going to be
plotted with the blue and higher pHs in red.

You can change the type of scale,
but let's go with this for now.

This is the color map that results,

and this is a nice way to visualize how

the pH conditions have changed
over the course of the year

from January on the left
to December on the right,

and the hour of day from
the top to the bottom.

This shows you that the highest
pHs always happen in the afternoon;

they tend to happen in summer,

and there have been times when the
higher pHs have been interrupted.

It turns out that this particular time period
in the middle was a period of higher flow,

as was this one over here,

and so that when the algae are
growing, to create higher pHs,

they need a lower flow condition.

The high flow disrupts the algal growth.

This is a great way to visualize
some of these patterns in the data.

Another way to kind of dig into the data

and understand some of the processes that
might be important is to take a look at

specialized X-Y graphs.
These are some of my favorite plots.

Let's choose the Klamath River
for this particular analysis,

and the site-- let's choose
the Miller Island site.

We're going to plot water temperature on the
X axis against dissolved oxygen on the Y axis.

Because the solubility of dissolved oxygen
is very much a function of water temperature,

we have the option here of including oxygen
percent saturation contours on that plot.

That will be interesting, and you'll
see that when it comes up at the end.

Let's choose all of the data; it's just four
years and so it doesn't take that long to plot.

We're going to highlight
some of the results by month.

This allows us to plot
different points in the graph

with different colors depending on
what month those points were measured.

Let's take a look at the result.

You'll see that we get some pretty
interesting patterns at this particular site.

The graph that we get, again water temperature
on the X axis and dissolved oxygen on the Y axis,

with these contour lines showing
constant percent saturation.

The solubility of oxygen as a
function of water temperature,

if we neglect barometric pressure,
is this thick dark line here.

Anything above that line are oxygen concentrations

that exceed the solubility;
we call that "supersaturated,"

and the only way that that can usually happen

is if there's enough photosynthesis
going on in the river

to produce an excess of oxygen.

Similarly, values below that
thick line are "subsaturated"

they are less than the solubility.

Usually the way that
that happens is that

there are processes in the
river that are consuming oxygen,

organic material that is being

decomposed by bacteria can
decrease the oxygen concentration.

One of the cool things about this plot
is that it shows an annual pattern.

If you take a look at the different colors
represented by the different months,

you'll see that in the springtime, you're kind
of moving towards the right along the solubility

with a little bit of supersaturation
showing that there's some algae activity,

but you don't get a lot of algal
activity until June or July,

in the purple and kind of orange colors,

but then at that point

you also get a lot of oxygen demands, and the
oxygen concentrations start going way down.

The oxygen levels at this site
actually will get very close to zero,

and they don't recover in the
fall and winter until very late

after some of those oxygen
demands have been depleted.

This is a really cool way of looking to see

at what time of year certain processes like algal
growth or decomposition of organic material,

along with solubility considerations,

all bring together all of those influences
into the dissolved oxygen budget of a stream.

You can really understand how
the system works a little better.

And of course,

the Data Grapher and Data Tabler system
allows you to actually access many of

the data that are used to
create all of these plots.

Under Tables, you can actually create
your own customized data tables.

If you were interested in data from the
Tualatin River at the Oswego Dam site,

you just select the parameters of interest,

select a daily statistic if
you wish, or a running average.

Choose a time period of interest, so we could
just choose, say, the most recent month.

Decide how you want to round those data.

You have the choice of outputting
data to the web browser,

or you can send it to a file that might
be easier to open up in a spreadsheet,

and just make the table. It's all
very simple, and there's the result.

So to sum things up, the Data
Grapher is a set of online programs

that allow anyone to explore and
visualize USGS time-series datasets,

make custom graphs and tables and
compare datasets among sites and years.

We think it's a great tool,
and we hope you enjoy using it!