Rivers are usually imagined as steady natural systems that always move in one direction, from high ground towards seas or lakes. That is the basic idea taught everywhere. Yet in different parts of the world, some rivers appear to flow backward for short periods or even seasonally. This does not always mean the river has permanently changed direction, but it often happens due to tides, storms, rainfall pressure, or human engineering that reshapes natural flow. Rivers like the Chicago River in the USA, the Tonlé Sap River in Cambodia, show this behaviour in different ways. Some changes are brief, while some are seasonal. A few are permanent due to human design, like the Chicago River. Together, rivers like the Tonlé Sap, Narmada, Mekong, and others show that river systems are flexible, constantly reacting to the world around them rather than following a fixed path.
List of Rivers That Flow in the Backward Direction
Chicago River, United States
The Chicago River in the US is one of the key examples of the reversed direction of a river. The river, in its natural form, was flowing towards Lake Michigan. This resulted in a major problem at the end of the 19th century when waste products of the city were discharged into the lake, which was also the source of drinking water. People decided to take a step that was nothing less than drastic. Canals and locks were constructed that reversed the course of the river. Instead of flowing into Lake Michigan, it now flows away from it towards the Mississippi River System.
Tonlé Sap River, Cambodia
The Tonlé Sap River in Cambodia behaves in a way that seems almost like natural reversal. During the monsoon season, the Mekong River rises rapidly due to heavy rainfall. When this happens, the pressure forces water to flow backwards into the Tonlé Sap Lake. Later, when the dry season arrives, the situation reverses again. Water drains back into the Mekong River, restoring normal flow direction. This cycle repeats every year.
Orinoco River, Venezuela
The Orinoco River in Venezuela sometimes appears to flow backwards because of a natural phenomenon called river bifurcation and seasonal water pressure changes. A part of its flow connects with the Casiquiare channel, which can redirect water towards the Amazon basin. During heavy rainfall, increased water volume can also push the flow in unusual directions. It is not a permanent reversal, just temporary and driven by geography and rainfall patterns across the basin.
Narmada River, India
The Narmada River in India exhibits both natural and human-induced changes in flow. In its lower stretches, strong tides from the Arabian Sea can push water backwards during high tide conditions. At the same time, dams and barrages regulate flow for irrigation and hydroelectric power. This adds another layer of control over natural movement. The result is a mixed system where river behaviour changes depending on both environmental forces and infrastructure management.
Mekong River, Southeast Asia
The Mekong River in Southeast Asia is part of a large interconnected water system. During heavy rainfall, water levels rise dramatically across the basin. This pressure can cause temporary flow changes in smaller connected channels. In some areas, water is pushed upstream due to flood redistribution. It is closely linked with the Tonlé Sap system, forming one of the most dynamic river-flood networks in the world.
Araguari River, Brazil
The Araguari River in Brazil was once famous for a tidal phenomenon called the “pororoca”. This was a powerful tidal bore where ocean waves travelled far inland, moving against the river flow. At times, it looked like the entire river was flowing backward. Surfers used to ride this wave before dam construction reduced its strength. It remains a well-known example of ocean force overpowering river currents.
