List of 7 Rivers That Flow Backward in the World

When we think of rivers, we think of water generally flowing, in a linear fashion, from high ground to the sea. Did you know there are some rivers on Earth that actually flow in reverse from their source to the sea? Rivers that defy the normal flow of water can do so because of a geological shift, tidal forces, earthquakes, or changes in sea levels. 

Although it seems hard to believe, these rivers have baffled the scientific community and explorers for hundreds of years. From the Amazon River to the odd Chicago River, they each have a unique story regarding their reversal. Let's dive into the seven fascinating rivers that go against nature and flow upriver in a unique way, it is very interesting that the rivers themselves do not follow the rules of geography. This list has been curated based on data by Mekong River Commission. 

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7 Rivers That Flow Backward in the World

Here are the top 7 rivers that flow backwards along with their location and the reason for their backward flow: 

1. Amazon River (South America)

The Amazon River at one time flowed westward, but the uplift of the Andes Mountains about 10 million years ago reversed the river's direction toward the Atlantic Ocean.

This tectonic and geological activity created the largest river basin in the world. The Amazon River carries more water than any river has ever carried, and it is proof of the power of Earth's natural forces to even make rivers flow backward.

2. Chicago River (United States)

As a man-made river, the Chicago River flows backward by design. In 1900, engineers reversed the flow of the river to prevent sewage from being dumped into Lake Michigan, which provided drinking water to the city.

By building canals and locks, the engineers successfully redirected the river toward the Mississippi basin. It was a monumental historic solution to an environmental problem as well as one of the greatest engineering feats in American history.

3. Mississippi River (United States)

The Mississippi River has flowed backward on multiple occasions, such as in the 1812 New Madrid Earthquake and Hurricane Katrina. Because of violent seismic activity and storms, the river, for short periods of time, reversed during the shaking and stranding the river's waves upstream.

These moments, though brief, were a powerful lesson about nature and even one of the world's strongest rivers being detoured from its original course.

4. Fraser River (Canada)

The Fraser River runs through British Columbia and experiences occasional backward flow, influenced by significant ocean tides from the Pacific. In certain conditions, usually involving exceptionally high tides, seawater progresses against the river’s flow, causing some short-term backward flow energy near the mouth of the river.

This fascinating natural occurrence captures the attention of scientists and travelers, and it demonstrates the ways that tidal actions can influence the behavior of even the largest rivers in unexpected ways. 

5. Tonle Sap River (Cambodia)

The Tonle Sap River in Cambodia reverses flow direction in a unique way each year. During the monsoon season rain, floodwaters from the Mekong River push the river backward, greatly increasing the size of the Tonle Sap Lake.

However, when the dry season returns and water levels drop, the Tonle Sap River returns to normal forward flow. This predictable, yet extraordinary, natural cycle feeds millions of people by replenishing fish stocks and nourishing Cambodia's rich agricultural ecosystem.

Conclusion

Rivers that flow in reverse teach us how dynamic and unpredictable the Earth is. Whether caused by the moon, tectonic shifts, or engineering decisions, rivers flowing backward are the epitome of change and dynamism in nature. Whether the Amazon River or the Tonle Sap, these remarkable rivers represent an incredible story of nature's dynamism and unpredictable reality.