Lesson V: Common Water Measurements Introduction The U.S. Geological Survey has been measuring water for decades. Millions of measurements and analyses have been made. Some measurements are taken almost every time water is sampled and investigated, no matter where in the U.S. the water is being studied. Even these simple measurements can sometimes reveal something important about the water and the environment around it. Another organization that measures water quality is GLOBE (Global Learning and Observations to Benefit the Environment). GLOBE seeks the answers to the following questions: What is the condition of the Earth's many surface waters - the streams, rivers, lakes, and coastal waters? How do these conditions vary over the year? Are these conditions changing from year to year? Through the GLOBE Hydrology Investigation, students address these questions by continuous, widespread monitoring of natural waters. GLOBE's knowledge of national and global trends in water quality is based on sampling at a very few representative sites. This sampling has generally been done only a few times. For example, information on many lakes is based on sampling done only once or twice more than ten years ago. Before we can assess changes, we need reliable information on current conditions. When changes are already underway, comparison of affected and unaffected areas can help us understand what is happening. Measures of dissolved oxygen and pH directly indicate how hospitable a body of water is to aquatic life. Again, it is interesting to both follow the annual cycle of dissolved oxygen, alkalinity and pH, and to make comparisons between different water bodies. We can ask such questions as: are dissolved oxygen levels always at the maximum allowed by the temperature of the water, or are they depressed during part of the year? If they are low, we want to know the cause. We can see if pH becomes depressed right after a rain or when there is a lot of snowmelt running off into the lake or stream. If we do find a depression in pH, we would expect that this water had a low level of alkalinity. In fact, we should expect that waters with a low alkalinity would have a depression in pH following rainfall or snowmelt. But we must make the measurement to confirm whether or not that really happens. Students make measurements with at least two societal goals in mind. First, they want to develop a better understanding of our local land and water resources. This knowledge can help us make more intelligent decisions about how we use, manage and enjoy the resources. Second, they want to assess the extent to which human activities are affecting the quality of our water and thus affecting how we will be able to use it in the future. In most countries current measurement programs cover only a few water bodies at a few times during the year. Measurements of water quality will help fill this gap and improve our understanding of the health of Earth's natural waters. Objectives: Students will demonstrate understanding of the following measurements of a water body's health: ph water temperature specific conductance turbidity dissolved oxygen hardness suspended sediment Students will develop and share related k-6 lesson plans. Activities: Students will study and discuss the ph property of water by reviewing the diagram on the website http://ga.water.usgs.gov/edu/phdiagram.html. Students will study the information regarding the use of the ph meter on the website http://ga.water.usgs.gov/edu/pictureshtml/phmeter.html and demonstrate the use of the ph meter to measure acidity. Students will study and discuss the use of sediment fences and how to measure sediment in a body of water: http://ga.water.usgs.gov/edu/sedfences.html. Students will study, discuss and demonstrate measurement of the following in bodies of water: specific conductance, turbidity, dissolved oxygen, and hardness from information located on the website http://ga.water.usgs.gov/edu/pictureshtml/sedfences.html as well as from the GLOBE website http://archive.globe.gov/sda-bin/wt?ghp/tg+L(en) . Demonstrations of the measurement of water properties will be conducted by cooperative learning groups, using GLOBE protocols from the website http://archive.globe.gov/sda-bin/wt?ghp/tg+L(en)+P(hydology/AtAGlance). Students will review, discuss, and demonstrate Hydrology protocols from the following NASA websites: Further Study of the Hydrosphere and Water on the Earth -http://search.spacelink.nasa.gov/query.html? Global Hydrology and Climate Center:(Studying global water cycle and its effects) -http://www.ghcc.msfc.nasa.gov/ghcc_home.html The Global Hydrology Resource Center -http://ghrc.msfc.nasa.gov/ghrc.html Regional Climate Assessment: Water Qualityhttp://www.ghcc.msfc.nasa.gov/regional/water_qualtiy.html Water Quality Protocols -http://search.spacelink.nasa.gov/query.html? More Water Quality Protocols -http://archive.globe.gov/sda-bin/wt/ghp/tg+L(en)+P(hydrology/AtGlance) Students will develop and share related k-6 lesson plans. [Return to Home Page]