Studying algal blooms in lakes, oceans or marine systems is relatively simple since blooms tend to concentrate at the surface. But studying the blooms in a river is much different. Flowing water tends to mix the algae from top to bottom.<\/p>\n
That\u2019s the case in the Ohio River, where Marshall University researchers are studying chlorophyll concentrations as a surrogate for algae. Key to their effort are images from the Landsat 8 satellite that can capture large sections of the river in a single snap. Scientists then ground-truth what the satellite finds with water samples. By combining the two approaches, researchers hope to develop a reliable way of estimating chlorophyll levels within the river using satellite images alone.<\/p>\n
\u201cWhen you have a long river, and the Ohio\u2019s close to 1000 miles long, typical sampling would take a liter of water every 80 miles or so and you do that about every two weeks,\u201d said Jeff Kovatch, associate professor of biological sciences at Marshall University. He is completing the work with Thaddaeus Tuggle, a graduate student in his lab. \u201cWell, the river doesn\u2019t sit still to capture the concentrations.\u201d<\/p>\n
The advantage that satellite technology provides is the capability to capture hundreds of miles of river in just one image, he says. That lets researchers see changes in chlorophyll concentrations over a much broader area than typical sampling.<\/p>\n
After the satellite collects its images, the values for light reflectance and absorption that it picks up are matched to the ground-truth data collected by Kovatch and others in the Ohio River\u2019s Greenup pool. They go about 30 meters offshore, where the river is well mixed, and collect samples using grab samplers. Collection takes place at three different locations at the same time on a given day. Different types of chlorophyll, a and b, are monitored by YSI sondes deployed along the pool while chlorophyll c is calculated in the lab.<\/p>\n
\u201cThat involves us going out, collecting the water samples and doing a chlorophyll extraction,\u201d said Kovatch. \u201cWe use that to fit a model of the different band values to different concentrations of chlorophyll.\u201d<\/p>\n
When comparing the model that he\u2019s helped develop with Tuggle, Kovatch says that it predicts chlorophyll concentrations really well. He declined to share an estimate of\u00a0the model’s\u00a0accuracy until after the final paper detailing the research is published, but he did have some plans for future studies that might use the model.<\/p>\n
\u201cWe would be able, from the comfort of one\u2019s computer, be able to sample chlorophyll concentrations across the entire Ohio River,\u201d said Kovatch. \u201cIn terms of time and money, we could collect a lot of detailed data quickly.\u201d<\/p>\n
In addition, by using historical images from NASA, Kovatch says it could be possible to extract the Ohio River\u2019s past concentrations.<\/p>\n
\u201cIf we can do that, we can get a 30-year data set, a temporal and spatial data set relating to the Ohio River,\u201d said Kovatch.<\/p>\n
Top image:\u00a0The Ohio River near the \u00a0J.T. Myers Lock and Dam as captured by Landsat 5 satellite in 2010. (Credit: NASA)<\/span><\/em><\/p>\n","protected":false},"excerpt":{"rendered":" Researchers at Marshall University use satellite imagery and grab samples to develop a model of the Ohio River\u2019s chlorophyll levels.<\/p>\n","protected":false},"author":13,"featured_media":22179,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,49],"tags":[308,158,60,284,289,109,285,348,283],"class_list":["post-22178","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-featured-articles","category-rivers-streams","tag-algae","tag-chlorophyll","tag-featured","tag-landsat","tag-marshall-university","tag-news-ticker","tag-ohio-river","tag-rivers-streams","tag-satellites"],"remote_post_permalink":false,"remote_post_featured_image":false,"yoast_head":"\n