Tag Archives | streamflow

RTD Activity Idea: Monitoring Streamflow

Streamflow over the course of 2012 from the USGS streamgage in Trenton, NJ

The task of monitoring the nation’s numerous streams and rivers falls to the United States Geological Survey. The USGS maintains a large network of instruments that record streamflow, water height, temperature, conductivity, water quality and several additional environmental variables. One of the chief uses of this network is to monitor the occurrence of floods and droughts.

Thanks to USGS’s National Water Information System, this data is easily accessible for students to access and visualize, allowing them to investigate river conditions at nearby locations or from across the nation.

Real-time Data Project

Here is a quick activity students can use to investigate current streamflow conditions and compare them with historical norms.

  1. Go to the Current Streamflow Map on the USGS WaterWatch site and select a state.
  2. Click on a station and note whether it is currently above, at, or below normal conditions, as denoted by the color of the dot.
  3. Click on the station ID number. This will take to you the station’s summary page.
  4. In the pull-down list, select “Time-series: Daily data
  5. The top of the page includes some basic information on the station, including its location, a photo of the station, and (for some stations) the upstream drainage area. Underneath this information is a box to customize the graphs appear on the page.
  6. Select “Graph w/ stats” as the output format and enter a date range you’d like to visualize. (Here’s an example that displays data from Trenton, NJ for all of 2012.)
  7. Find the graph for discharge or gage height and compare how the measurements (shown in blue) compare with the historical average (shown in yellow).
  8. If you choose a full year (i.e. from January 1st to December 31st) you can quickly get a good idea of the annual differences and seasonal cycle at a station. (For example, for the Trenton station above, the highest average streamflows are typically seen in March and April, while the lowest occur in the summer and early fall.)
  9. Now that you have the hang of it, you can create graphs for individual years to compare them with each other, or you can look up data around specific events you know of, like major rain storms or droughts.

Engaging Questions

Here are a few questions students can think about before they start their research.

  • What do you know about floods and droughts? What causes them? What impacts do they have on the environment, ecosystems and people?
  • How do you think scientists study river flow? (The two primary methods are gage height and streamflow.)

Suggested Research Questions

Here are several questions students can try to answer by looking at the data.

  1. For your selected station, how does the most recent measurement compare with the current streamflow status (i.e. percentile class) shown on the map?
  2. How long has the station be at that state?
  3. What times of year have the highest streamflow? Which times have the lowest?
  4. Were there any times during the year where the streamflow was exceptionally high or low? Do you have any idea what may have caused these observations?

Relevant References

The WaterWatch web site, also maintained by the USGS, aggregates data from the entire stream gage network into a great set of maps, highlighting the current streamflow, drought and flood conditions around the country. If students are interested in looking at current or past conditions across the nation as a whole, this is a great place to start.

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USGS WaterWatch

USGS WaterWatch Web SiteIt’s April. And while the cold temperatures here in New Jersey make it feel like spring hasn’t quite yet arrived, the flowers are starting to poke through the ground, reminding us that spring is coming, and with it, a steady stream of springtime showers should be on their way.

Of course, when rain falls on land, much of it ends up in rivers and streams. And thanks to a network of over 3,000 stream gages monitored by the U.S. Geological Survey, we can easily study how precipitation, including rain and snow, impacts local streams, rivers and estuaries.

All of this data is available on USGS’s WaterWatch web site, which features several easy to use maps, providing a great  way to introduce streamflow data to students and the public, while showcasing how it can be used to monitor floods and droughts – critical issues related to human health, safety and well-being.

Here are a few great places to start.

Current Streamflow Map: This map displays the real-time conditions from all of the streamflow stations across the country.  Some stations measure streamflow discharge or flow rate, while other stations measure gage height, that is, how high the water level is. A few stations even measure other things like temperature, pH and dissolved oxygen. From this map, you can select an individual station to view in detail, access raw data or create custom graphs.  

On the map, each station is represented as a colored dot, whose color is based on how the current streamflow or gage height compares with past records.  Reds designate those stations that are below average while blues are above average, and green dots represent those stations that are in line with historical norms. You can also view historical streamflow maps.

Drought Map: This map highlights which areas of the country have below normal streamflow conditions, typically due to long periods of time with limited rainfall or, in mountainous areas, low levels of wintertime snowpack. Below normal streamflow is generally a good indicator of whether a drought exists, though precipitation, ground water and reservoir levels are also taken into account when declaring an official drought. (See for example, New Jersey’s Drought Information Site.)

Flood Map: Sometimes, you can have too much of a good thing. This map shows those stations stations that are currently reporting conditions drastically higher than their historically normal levels. This can often happen after severe storms with large amounts of precipitation (which is especially true after tropical storms and hurricanes), but it is also common in the spring when mountain snowpack melts. And of course, some rivers are susceptible to a springtime a double whammy.

Personally, I’ve always wondered if a more appropriate phrase for this time of year might be “April flowers bring May showers,” but to make that case, I need to dig through this data some more.

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