The Himalayas, being a young and tectonically active mountain range, exhibit dynamic fluvial processes, including river course shifting and river capturing. River course shifting, also known as avulsion, occurs when a river abandons its old channel and carves a new path. In the Himalayas, this is often triggered by high sediment loads, particularly during monsoon floods, which can choke existing channels and force the river to seek new, lower-gradient paths. Tectonic uplift and seismic activity can also alter river gradients and lead to course changes. The Kosi River in Bihar, often called the 'Sorrow of Bihar,' is a classic example, known for its frequent and dramatic shifts due to its enormous sediment load and braided nature.

River capturing, or stream piracy, is a geomorphological phenomenon where a more energetic or rapidly eroding river (the 'captor') erodes headward and intercepts the flow of another, less energetic river (the 'captured'). This typically happens when rivers flow on different sides of a watershed divide, and one river, due to a steeper gradient or softer rock, erodes faster. In the Himalayas, the intense headward erosion by antecedent rivers (those that predate the mountain uplift) and subsequent rivers (those that form after uplift) through softer sedimentary rocks or along fault lines can lead to capturing events. This process reshapes drainage patterns, often resulting in sharp bends (elbows of capture) in the captor river and a dry or underfit valley (wind gap) where the captured river once flowed. Both phenomena highlight the ongoing geomorphic evolution of the Himalayan landscape.