Why would a river no longer be able to carry a load across its course?

A river may no longer be able to carry a load across its course due to a decrease in water flow, often caused by drought, upstream water extraction, or changes in precipitation patterns. Additionally, sediment buildup can create shallower areas or bars that obstruct the flow, limiting the river's capacity to transport materials. Environmental changes, such as dam construction, can also disrupt the natural flow, reducing the river's ability to carry its load effectively.