Tip:
Highlight text to annotate it
X
This is the third in a series of three videos showing the functionality of the USGS sediment
data portal. In this video we will show the data contained within the files you downloaded
from the portal. Let's take a look at the data we downloaded.
Today I'm going use Microsoft Excel to show the data because it is useful for that purpose,
but you can use a variety of software packages to open up and interpret your data. If you
remember I put my data in a folder in my "My Documents" folder in a folder called "sedportaldownload".
I'll click there. You'll see that I have 4 files in my folder. Sometimes Microsoft excel
will display no files because its default is all Excel files, just note that you'll
need to go al "All files" to display you data. You can see the four files we downloaded earlier.
Let's go and open up daily data. A test import wizard pops up, we picked a tab-separated
file, we can hit next and see that the tab-delimiter is selected by default because Microsoft Excel
recognizes this as a tab-separated file, so you'll just go over and hit "finish".
We can see our file. These first 18 lines are header information. This first row is
a disclaimer. This third row indicates that whenever we have a new site, we downloaded
three sites, the new site will be delimited by this long series of #'s, the indicator
NEW SITE, and another long series of #'s. It is important because sometimes daily flow,
daily sediment concentration, and/or daily sediment load information will be available,
and if different amounts of data are available these columns may change so you need to make
sure you're aware of that. It gives definitions for the fields, we have
agency ID, which it typically will be the USGS whom collected the data. The USGS site
number, note that within Excel, the site number field is recognized as a number, and so the
leading zero is dropped, that won't always be true with other software applications.
You get a date/time, this is daily data, so they each have a date. We get daily flow information,
in cubic feet per second, and daily flow qualifier which indicates that this information is approved.
We get daily suspended-sediment load information for this site, in tons per day, and the qualifier
for those data. You are probably observing that we don't have
any sediment loading information initially but we do have flow information. This will
often be the case when you download daily data because typically the streamgage will
have been operational before sediment load or sediment concentration data will have been
collected. The way that we download data gets all of the daily flow information. Let's go
to the sediment load information by clicking "control down" and we'll scroll down to the
first sediment load entry and we can see that on October 1st 1969 we had one ton per day
and that data is approved. I'll hit control down again, that should take us to the end
of the sediment load information for this site in 1974. If I hit control down one more
time, it will take us to a new site, you can see down here a different USGS station ID,
and we have more daily information, in this case we also have suspended-sediment concentration
and the qualifier for suspended-sediment concentration and our load information is out here to the
right. So you can see that fields F and G in excel changed from load to concentration.
Hopefully future versions will have this fixed so the data will always be in the same columns,
but it is rather complicated. To go down and look and look at our new site, hit control
down on suspended-sediment concentration and you can see that our first data entry is in
1957, we have a suspended-sediment concentration of 113 milligrams per liter and 3.1 tons per
day were transported for this concentration and flow value.
Now let's go look at our discrete data. I'll click open and go back to my "sedportaldownload"
folder, and I will click on discrete data. Again we can just hit finish, because Excel
will find the tabs. I'll move my window a little bit. You can see we have a much longer
header because we have a lot more information with our discrete data, going down to line
52. The information we have includes the USGS site number, the USGS station name, the date
and time of sample collection, the "dcomment" and "icomment" field are quality control codes,
look into the user guide for more information on those, suspended-sediment concentration,
information on daily or instantaneous streamflow, gage height, rows 13 through 23 are various
categories of suspended-sediment grain size information, we loss on ignition, "TSS" and
"SS" are different codes for suspended-solids. Rows 27 through 32 are various information
on how the sample was collected, the method, the purpose, the type of sample, etc. We have
width and velocity, rows 35-41 indicate different measures of turbidity, water temperature,
air temperature, different measures of specific conductance, dissolved solids, pH, and in
some cases there are samples that have end dates and end times, generally these are samples
that have been collected over a long period of time, this is relatively rare. Down below
this, you can see our data. You can see that the "datetime" field has a specific date/time
stamp. For the discrete data, all of the data are in the same columns, as you scroll down,
you'll see that you have a new site id, but the site ID will change, there is no new site
identifier, because all of the fields are in the same columns.
Now let's go look at our site attribute information. Back to my "sedportaldownload" folder, I'll
click on daily sites, again daily sites and discrete sites contain the same type of information;
daily sites correspond to sites in the daily data file, discrete sites correspond to sites
in the discrete data file. So again, just hit finish. I'll move the location of my window.
There are a lot of data in our site attribute file. There is information on site number,
site name, latitude/longitude, upstream drainage area, state and county name, we have both
the codes and names for level 1, 2, and 3 ecoregions. We have the codes and names for
HUC 2, 4, 6, and 8 (region, subregion, basin, and subbasin). We have average upstream landscape
characteristics, average upstream soil permeability, baseflow index, soil erodibility (K factor),
rainfall-runoff factor (R factor), average precipitation from 1971-2000, percentages
of urban, forest, and agricultural land use, the number of major dams as identified by
the national inventory of dams, there is a specific categorization as to what is or isn't
a major dam. We have the total national inventory of dams storage in acre-feet, percentages
of clay, sand, and silt on average in the upstream basin, this benchmark field indicates
whether the site selected is a USGS hydrologic benchmark site, and then all these NHDs from
row 39-53 indicate daily flow percentiles, and then we also have the number of years
samples were collected for the daily data and the sample count in the case of discrete
data. By pulling down you can see the three daily sites we have selected. So that is the
end of the demonstration as to what the data look like that you downloaded.
Thank you for taking the time to learn more about the USGS Sediment Data Portal. Again
to get to the portal, go to cida.usgs.gov/sediment, to get to the associated report, go to pubs.usgs.gov/ds/776.