SUMMARY

In this activity developed by NOAA, students learn about tides and salinity in  estuaries. They observe time-lapse models of tides and salinity distribution in the York River, part of the  Chesapeake Bay, VA NERR. Learn how salinity changes with an incoming and outgoing tide, observing the  dynamics of the salt wedge at various sites along the river. Students also make predictions about the salinity changes at each site based upon their observations of the animation. They then use salinity data from  monitoring stations along the river to see changes during a typical day. And, then describe the patterns of each  salinity graph and compare the graphs.

GOALS

Students will be able to:

1. Analyze different forms of data and synthesize  information to develop a hypothesis.
2. Explain how tides and the geology of the estuary affect water circulation in an estuary.
3. Describe daily patterns of salinity changes in the  estuary.

CONTEXT FOR USE

Teaching Time: 3 (55 minute) class sessions + homework

Organization of the Activity: This activity consists of 3 parts which help deepen understanding of estuarine systems:

1. Tides in Chesapeake Bay
2. Salinity as York River Flows into the Bay
3. Interaction of Tides and River Flow

Preparation:

1. Make copies of Student Reading — Estuarine Tides, Student Worksheet — Salinity and Tides, and if you will not be  providing computer-access to the data, Student Data Sheet — Salinity and Tide Data for York River. (Note that the data on the Student Data Sheet are for a specific date: March 21, 2007.)
2. Arrange for students to work with the animation and data, either in a computer lab or with a computer and projector. Bookmark the following sites:

• nerrs.noaa.gov/ChesapeakeBayVA/welcome.html
• tidesandcurrents.noaa.gov/ofs/cbofs/wl_nowcast.shtml
• www.vims.edu/physical/web/presnt/qtime/Kimplot3.mov
• www2.vims.edu/vecos/SegmentChoice.aspx?param=MOBPH

ACTIVITY DESCRIPTION AND TEACHING MATERIALS

Teacher Guide—Earth Science Module
Activity: Salinity & Tides