by US flows run hot.
A new analysis of almost 1,500 river locations over more than 40 years showed that the frequency, intensity and duration of the heat waves in streams increases across the country and is a threat to many species that are adapted to cooling temperatures.
“The trend of river heat waves actually increases faster than the air heat waves. So that’s a thing that is very surprising,” said Li Li, professor of environmental technology at Penn State University and the study.
The new analysis published in the Journal Professions of the National Academy of Sciences examined by experts is the first incoming study on river heat waves that are defined with high temperatures compared to seasonal average values.
The authors found that humans caused by humans are the main driver of the trend because the snow cover disappears and streams flow more slowly.
Other human factors also affect the trend. Dams slow down the water flow downstream. Buildings and pavement remove heat that heats the air and then the water.
Scientists expect species that are dependent on cold water, including salmon and trout, will increasingly struggle with the increase in streams. Li said it would be important to document fish kills to see whether and which trends appear.
Heat reduces the amount of dissolved oxygen in the water. In the meantime, cold water types often rise in warmer waters, which means that less oxygen is available.
The findings could provide information on how to manage water catchment areas and whether changes to the irrigation or dam exemptions could help keep the types in hot weather.
“The way we use water, how we manage these resources, can affect heat waves,” said Jonathan Walter, a research scientist at UC Davis’ Center for Watershed Sciences, who was not involved in this research. “Under the assumption of sufficient amounts of water in a reservoir, we can possibly release water so that the downstream temperatures are cooled somewhat and would prevent them and prevent stressful temperatures.”
Heat waves have been examined in detail in oceans and lakes, but so far researchers have only had limited information about how higher temperatures influenced the streams.
Satellite data drives the research of heat into oceans and lakes. Studying the flow temperatures is more difficult because they are dependent on stream-gauge sensors who are often in and outside the company and can be difficult to analyze data that is difficult to analyze.
From 1980 to 2022, the researchers collected data from 1,471 US Geological Survey Stream Surveillance locations from 1980 to 2022.
The data enabled the researchers to evaluate changes in streams nationwide. They found that river heat waves took place more often in 2022 than in 1980 – with an average of 1.8 additional heat wave events per year. The heat waves were also more intense, with temperatures for heating events by about 0.8 degrees fahrenheit higher on average compared to 1980.
Li said the additional heat causes an average of about 12 days of heat stress for species that require cold water. The authors of the study used 59 degrees F as a threshold for heat stock because some types such as bull trout have difficulties to survive through this marker.
“If we think above water, there is a lot more attention about the amount because we can see it,” said left. “We hope that this type of study will increase public awareness of the problem of water quality in connection with climate change.”
This article was originally published on nbcnews.com
