The average lifespan of a river can vary significantly, influenced by factors such as geography, climate, and human activity. Generally, rivers can last anywhere from a few hundred to several thousand years, depending on their environment. Natural processes like sediment deposition, erosion, and climate change can impact river longevity. Additionally, human interventions such as damming, land use changes, and pollution can drastically alter a river's ecosystem and even lead to its disappearance. Understanding the lifespan of a river is crucial for conservation efforts and managing freshwater resources effectively.