Much like the sky, rivers are rarely painted one color. Rivers around the world appear in shades of yellow, green, blue, and brown—and subtle changes in the environment can alter their colors.


New research shows the dominant color has changed in about one-third of large rivers in the continental United States over the past 35 years.


The figure above shows data from a map of river color for the contiguous United States. The rivers are colored as they would approximately appear to the human eye. The map was built from 234,727 images collected by Landsat satellites between 1984 and 2018. The dataset includes 67,000 miles (100,000 kilometers) of waterways of at least 200 feet (60 meters) wide.

上图显示了来自美国毗连河流颜色地图的数据。河流的颜色与人眼所见的大致相同。该地图是根据地球资源卫星在1984年至2018年期间收集的234,727张图像构建的。该数据集包括67,000英里(100,000公里)、至少200英尺(60 米)宽的水域。

While is not unusual for rivers to change colors over time due to fluctuations in flow, concentrations of sediments, and the amount of dissolved organic matter or algae in the water, scientists have found that the most extreme changes often occur near man-made reservoirs. Around 56 percent of rivers were dominantly yellow over the course of the investigation, and 38 percent were dominantly green.


Want more? Read Amazing Earth: Satellite Images from 2021

想要了解更多?阅读惊人的地球:2021 年的卫星图像

Image Credit: NASA Earth Observatory image by Joshua Stevens, using data courtesy of Gardner, J., et al. (2020).

影像来源:NASA Earth Observatory image by Joshua Stevens, using data courtesy of Gardner, J., et al. (2020).

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