logo-b81fc6af2faedb728fbd5fa5eeed23730c5b8be653318097907f3f0a5adbc5a6
Click for a Unique Window into the Untouched Amazon Waterway: Watch Live Now! (Courtesy of Junglekeepers)

Flipping the Script: Rivers Flowing Backwards

Picture this: The escalators in your local subway station suddenly reverse direction, carrying people up instead of down. It would be a strange and unexpected sight, causing a momentary disruption to your routine. Something similar can happen in nature: rivers can occasionally reverse their flow, creating a phenomenon as unexpected and intriguing as a backwards escalator.
Love this cover artwork? Check out the 5 alternatives above the comment section below.

Table of Contents

The Causes of River Reversal

Rivers, vital lifelines of our planet, have been known to reverse their flow, both permanently and temporarily. While permanent reversals are often caused by geological forces, temporary reversals can be triggered by natural events or human interventions.

Permanent Reversals

Permanent Reversals are irreversible changes in a river’s course, often resulting from tectonic shifts or large-scale geological processes. For instance, the Amazon River, once flowing into the Pacific Ocean, was redirected towards the Atlantic Ocean due to the uplift of the Andes Mountains.

Temporary Reversals

Temporary Reversals, on the other hand, are short-lived changes in a river’s direction, typically caused by factors such as seasonal variations, extreme weather events, or human activities. Tidal rivers, for example, experience daily reversals due to the gravitational pull of the moon and sun.

Sufer Tidal Bore River Mixer
Surfing a Tidal Bore (The Silver Dragon) on the Qiantang River

Example of both Natural and Artificial Permanent Reversals

Permanent Natural Reversals

  • Amazon River: Originally flowed into the Pacific Ocean but was redirected towards the Atlantic Ocean due to the uplift of the Andes Mountains during the Cretaceous period.

  • Wisconsin River: Once flowed into the Great Lakes Basin but was rerouted towards the Mississippi River due to glacial activity during the Pleistocene Epoch.

Permanent Artificial Reversals

Example of Daily, Annual and Intermittent Temporary Reversals

Temporary Daily Reversals

Temporary Annual Reversals

Temporary Intermittent Reversals

The Tidal Bore: A Natural Phenomenon

Imagine a massive, moving wall of water surging up a river. That’s essentially a tidal bore. It’s like a natural tsunami, but smaller and happening regularly. Think of it as the ocean trying to flood a river, and the river putting up a fight.

The tide comes in from the sea, and as it reaches the river’s mouth, it gets funneled into a narrower channel. This creates a powerful surge that can travel miles up the river, sometimes even reaching inland cities. It’s like when you try to squeeze water out of a balloon, but instead of popping, it forces its way out in a powerful jet.

The Porocora Amazaon River Mixer
Surfing a Tidal Bore (The Porocora) on the Amazon River

A River's Double Reversal: The Case of the Chicago River

As you may have observed, the Chicago River has experienced two distinct flow reversals. Initially, it was permanently reversed in the early 1900s to divert sewage away from Lake Michigan. However, in recent years, the river’s flow has been temporarily reversed during periods of heavy rainfall to prevent flooding. While the permanent reversal was a major engineering feat to improve water quality, the river’s natural tendency remains to flow towards Lake Michigan. Although it would be challenging and costly to revert the river’s flow back to its original direction, understanding its natural inclination is important for managing its future.

To understand the broader scientific forces that shape these landscapes, explore our comprehensive guide on Fluvial Geomorphology, where we break down the five stages of river evolution and landform creation.

Keep them clean!

As we’ve seen, rivers can change their course, both temporarily and permanently. These shifts are a testament to the dynamic nature of our planet and the intricate balance of forces that shape our waterways. Reflecting on these events reminds us of the importance of protecting our rivers and understanding the factors that influence their flow.

F.A.Q.

River reversals can be caused by both natural and human factors. Natural causes include tectonic shifts, glacial activity, and extreme weather events. Human interventions, such as dam construction and canal digging, can also lead to reversals.

Permanent reversals are irreversible changes in a river’s course, often resulting from geological forces. Temporary reversals, on the other hand, are short-lived changes caused by factors like tides, extreme weather, or human activities.

Yes, rivers can naturally reverse their flow due to geological changes, such as the uplift of mountains or the movement of tectonic plates.

The Amazon River, once flowing into the Pacific Ocean, is considered the longest river that has reversed its flow due to geological changes.

River reversals can have significant environmental consequences, including changes in ecosystems, disruption of wildlife habitats, and impacts on water quality.

Additional resources

Related Content
Don't miss a drop.
Sign up for new river alerts! We're continually expanding our collection with amazing waterways from around the globe. If you're searching for a specific river to enhance your craft, spiritual or research practices, subscribe to stay informed.
subscribe
Editor's note

This blog post uses publicly available information from various sources, synthesized with the help of AI, as a starting point for exploring the world of rivers. Our editors review the content for accuracy, though we encourage readers to verify information intended for primary source use. We strive to use public domain, licensed, or AI-generated images; due to the nature of online sharing, individual image sources are generally not credited. Please contact us regarding any copyright concerns.

Featured Friends
Worldly Adventurer.
Worldly Adventurer is a travel blog focused on exploring the vibrant and diverse landscapes of Latin America. Created by Steph, a seasoned travel journalist and guidebook author, the blog offers expert insights, personalized itinerary planning, and a commitment to sustainable travel. Discover hidden gems, experience local cultures, and embark on unforgettable adventures with Worldly Adventurer as your guide.
featured
our river collection
Crossword Puzzle

Collection Map
Let's Celebrate.
Travel the world, one river at a time. Explore our map and follow us as we collect precious rivers. Become part of the story by owning your own drops of history.
map
River Clips
Collection Videos.
Trace the origins of our extraordinary river water collection. Watch captivating video clips that capture the breathtaking birthplaces of these rivers.
videos
Be a River Guardian
recent posts
News
Central Saudi Arabia Flood Update: Wadi Hanifa and Wadi Al-Batha Levels Rising in Riyadh, Al-Kharj

Current monitoring shows water levels nearing bank-full at the Wadi Hanifa Wetlands as of April 17, 2026. While the Kingdom’s desert wadis often remain dry, the current atmospheric pressure system has triggered significant runoff, turning dry riverbeds into dangerous torrents that threaten low-lying residential sectors and critical transport arteries across the central plateau.

Read More »
History
Book Review: The Invention of Nature by Andrea Wulf – The Global Web of Life and the Forgotten Father of Environmentalism

Andrea Wulf doesn’t hand you a dry historical record; she restores the physical muscle of a man who saw the world as a single, breathing organism. From the 19,413-foot ledge of Chimborazo to the Krakow shelves where the journals were filed, this review looks at the grit required to map the global Web of Life. It’s time to rediscover the surveyor who warned us of a changing climate two centuries before the world was ready to listen.

Read More »
Alternative Covers

We had multiple art options for this post’s cover, but only one could make the cut. Here are 5 runner-ups. Did we choose the right one?

Leave a Reply

Your email address will not be published. Required fields are marked *

For security, use of Google's reCAPTCHA service is required which is subject to the Google Privacy Policy and Terms of Use.