Rivers

“Hey Rupam, open the door. Take this fish,” a woman yelled from outside. I was sitting in the kitchen at my friend Rupam’s house in rural northeast India. It was the heart of monsoon season, and rain had been falling since morning. The woman must have been shouting because the noise of the rain on the tin roof muted everything else. The aunty who lived next door stood outside with a large bowl of Boriala fish. Her husband had gone fishing on the Subansiri River, which flows next to the village, and he had fished all evening. “My husband cannot stay indoors in this weather,” she said in Assamese, the local language. “You can catch a lot of fish during this time.” The monsoon season has long brought a bounty of fish from May to September for people living downstream. However, this is likely to change once the Subansiri Lower Hydroelectric Project, one of the largest hydropower dams in India, is completed upstream. Expected to be fully op...

As the Arctic warms, its mighty rivers are changing in ways that could have vast consequences – not only for the Arctic region but for the world. Rivers represent the land branch of the earth’s hydrological cycle. As rain and snow fall, rivers transport freshwater runoff along with dissolved organic and particulate materials, including carbon, to coastal areas. With the Arctic now warming nearly four times faster than the rest of the world, the region is seeing more precipitation and the permafrost is thawing, leading to stronger river flows. Major river basins of the Arctic region. NOAA Arctic Report Card We’re climate scientists who study how warming is influencing the water cycle and ecosystems. In a new study using historical data and sophisticated computer models of Earth’s climate and hydrology, we explored how climate change is altering Arctic rivers. We found that th...

The Rio Grande is one of the longest rivers in North America, running some 1,900 miles (3,060 kilometers) from the Colorado Rockies southeast to the Gulf of Mexico. It provides fresh water for seven U.S. and Mexican states, and forms the border between Texas and Mexico, where it is known as the Río Bravo del Norte. The river’s English and Spanish names mean, respectively, “large” and “rough.” But viewed from the Zaragoza International Bridge, which connects the cities of El Paso, Texas, and Ciudad Juárez, Mexico, what was once mighty is now a dry riverbed, lined ominously with barbed wire. The Rio Grande is one of the largest rivers in the southwest U.S. and northern Mexico. Because of drought and overuse, sections of the river frequently run dry. Kmusser/Wikipedia, CC BY-SA In the U.S., people often think of the Rio Grande mainly as a political border that f...

Seawater intrusion is the movement of saline water from the ocean or estuaries into freshwater systems. The seawater that has crept up the Mississippi River in the summer and early fall of 2023 is a reminder that coastal communities teeter in a fragile land-sea balance. Fresh water is essential for drinking, irrigation and healthy ecosystems. When seawater moves inland, the salt it contains can wreak havoc on farmlands, ecosystems, lives and livelihoods. I am a coastal hydrogeologist and have studied water across the land-sea interface for 25 years. I think of seawater intrusion as being like a seesaw: The place where fresh water and salt water meet is the balance point between forces from land and forces from the sea. A push from the land side, such as heavy rainfall or high river flows, moves the balance point seaward. A push from the sea side – whether it’s sea-level rise, storm surge or high tides – moves the balance point landward. Droughts or heavy us...

Invasive species – including plants, animals and fish – cause heavy damage to crops, wildlife and human health worldwide. Some prey on native species; other out-compete them for space and food or spread disease. A new United Nations report estimates the losses generated by invasives at more than US$423 billion yearly and shows that these damages have at least quadrupled in every decade since 1970. Humans regularly move animals, plants and other living species from their home areas to new locations, either accidentally or on purpose. For example, they may import plants from faraway locations to raise as crops or bring in a nonnative animal to prey on a local pest. Other invasives hitch rides in cargo or ships’ ballast water. When a species that is not native to a particular area becomes established there, reproducing quickly and causing harm, it has become invasive. These recent articles from The Conversation describe how several invasive species are causing eco...