CE/NR 797 Lab:  Water and wind circulation around Gibraltar Island  

[Prepared by R. Fortner for “Digital and Field Techniques for Coastal Environment Studies,” 7/02]

With changing wind patterns the water flows differently around Gibraltar and Put-in-Bay. While there is little that can be done to change the wind direction, perhaps there is a pattern of predictable change that can be useful to people entering and leaving Gib and the Bay for recreation or research. Your combined skills in GIS, GPS and field data collection can answer important questions about how water moves and what factors change with that movement.

 Objective: 

To develop a general model of the relationship between physical movements and characteristics of lake components around Gibraltar Island, for purposes of prediction and to facilitate research.

 Materials:

  Bathymetric map of the Gibraltar/Put-in-Bay area, sounding line or other depth measure, anemometer, GPS, stopwatch, meter stick, flow meter, secchi disk, GLFS nowcasts, buoy data from Internet.

 Procedure: 

During the 4 main weeks of the course the class will study the relationships between wind, waves, water current, water level and light penetration. Temperature (air and water) is always important too. The same data can be related to water chemistry in another lab. Accuracy of measurement within the limitations of the instruments is important.

Two areas were chosen to yield different kinds of information about the same set of parameters to be measured: the “Red Can” buoy northwest of Gibraltar, and a line of docking buoys from the Gib dock almost to the Boardwalk on South Bass. Use maps and observations to identify in your lab report the general characteristics that define the two water environments.

A daily set of measurements should be taken at the designated sites off Gibraltar Island. A team of 2-3 students will monitor the same site for the entire period of the lab, or you may choose to rotate from Bay to Lake. Measurements should be taken from the same sites at about the same time each day, but Bay measurements do not have to be at the same time as Lake ones (equipment is limited). Your team is responsible for reporting accurate data and posting it weekly (Friday after last sampling).

Results:

Record your data on the attached sheet or modify it to meet your needs (file available from Hongxia).  Transfer the data to an Excel file that you call CircLab. The sheet should have a place for your own data and one for the data from the other team. Designate these as Bay or Lake data.

Your data will be used in creating a GIS map of the circulation of the surface and subsurface water, and the relationships of waves, water transparency, and wind to that circulation. With this information you will be able to answer practical questions about coastal processes. Specific questions and lab report instructions will be available  before July 4.

 For example, under what conditions would you prefer to sample the lake bottom at 2 meters in a given location? If you disturb the sediments at that time, where do they go? How much does water level change when a southwest wind blows for 8 hours at 10 knots? Are you likely to get your sailboat stalled when you leave the lake and enter the bay? Is there enough water to set up your 8 meter sampling gear? Who needs to know this information?  

Water and wind circulation lab report Guideline

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