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.
