Satellite images of U.S. rivers have revealed a color-changing trend: over the past three decades, a third of the blue rivers in the past have turned yellow or green. The findings come after an analysis of about 235,000 images taken between 1984 and 2018. Among the color-changing rivers, 56 percent were mostly yellow and 38 percent were mostly green.
Findings, published in the journal Geographical research papers, Come from a team of researchers who wanted to try to use water color to give an understanding about the health of the river. It sounds like a common technique that even non-scientists can do, but the scientific community has avoided color observations in favor of obtaining real river samples.
Which would be fine, if the samples weren’t so rarely obtained.
The authors write that “rivers are among the most compressed ecosystems globally,” however, we do not have a broad-minded understanding of their changing ecology, as most are rarely sampled. “
So the team thought that extensive, visual observations of river colors could help when very little data on river health was discovered. Tracking color can also give researchers a better idea of current trends, patterns, and areas of alarm. And, nowadays, the quality of satellite images is so good that it can make river investigations much easier.
“[River color] “It’s a very simple metric,” lead author John Gardner told Live Science. But it can be used to identify areas that are changing really fast. “
The research team also plotted the colors of the river on an interactive map, giving a great view of the change in the sky.
But what do the colors of the river mean? Well … scientists aren’t completely sure yet. Rivers sometimes change color due to silt filling up when seasonal snow melts. Sometimes there is a period of rivers where a mass of algae temporarily makes it green. At other times, human activity causes disturbances in the environment that alter water quality and, therefore, color.
It really depends on what is common to the river, which is why it is so important to observe their color. It is not uncommon for rivers to be blue, green, yellow or brown. But if a sudden change occurs, it could be a sign that something is wrong.
“Most rivers are slowly changing and are not significant to the human eye,” Gardner explained to LiveScience. “But areas that change the fastest are more likely to be man-made.”
While more research is needed to determine precisely what color research means, the authors maintained that “water color tracking can direct rivers passing through rapid environmental change and work towards an understanding of river continents.”
