More than 75000 rivers of the USA are changing their color due to the impact of environmental change!

 Innumerable rivers in the USA are changing color! Is it a bad sign? Is it a matter of concern? Know the complete story here!

Rivers and their colors

Rivers display a particular color though they are made of water. This color comes from the amount of algae, sediments, dissolved organic carbon and other things in the water of the rivers. The color gives an indication of the quality of water in it. Hence some of the rivers appear light blue; some have a deep blue hue whereas some are greenish in color.

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Interactive map [Source: The Hill]

If we look at the rivers of the USA, a new study has revealed that the color of the rivers in the US is changing color. It is due to regional differences, seasonal differences and also due to the impact of the environmental change on them. Around 75000 rivers in the US have revealed this changed color pattern.

The University of North Carolina study findings

John Gardner, an environmental scientist from the University of North Carolina in Chapel Hill says:

"Water color, as perceived by the human eye, is … an intuitive and broadly applicable water measurement,"

"It is intuitive since it is based on human perception of color, and people often discern water's suitability for consumption, recreation, and aesthetic value based on water color."  

The researchers used NASA and USGS Landsat satellite imagery from 1984 to 2018 to see the full-colour distribution of the rivers in the USA over time. The rivers revealed seasonal variations. On the interactive map, red color implies the river is yellower and this is noticed in spring and summer. And a blue color shift implies that the river is greener.

38% of the rivers revealed a blue shift and the remaining showed a redshift. The study did not associate these findings with the eater quality of the said rivers of the USA.

What the findings imply?

The US Geological Survey explained this pattern of the rivers in the USA over time. They said that yellower water means that it is mixed with more tannins and dissolved matter. These include algae and dinoflagellates. While green water means that there is more of phytoplanktons or other algae.

The interactive map shows that many of the rivers in the Northwest part of the USA are blue-shifted. And those on the Midwest region and east coast are red-shifted. But the rivers near the Gulf of Mexico are of the same color and show no variations from their before pictures. The authors have explained:

"The prevalence of blue-shifted trends in the western USA and red-shifted trends in the eastern USA suggest there are regional drivers of long-term trends, including changes in hydroclimate (e.g. river flow), land use, and watershed management,"

But the problem is that most of these rivers are in places that are difficult to reach. Hence the water quality there cannot be tested. But by using these imageries, one can monitor and check on the hotspots of change.