A river terrace is a relatively flat, elevated surface that borders a river valley. It represents a former floodplain that was abandoned as the river downcut and migrated laterally.

River terraces are formed as a result of the lateral migration of the river channel. As the river meanders and changes course over time, it leaves behind abandoned floodplains that become elevated above the current river level.

An abandoned channel is a former river channel that is no longer actively carrying water. It may have been abandoned due to changes in the river's course, avulsion, or the formation of a new channel.

Abandoned channels are formed as a result of the lateral migration of the river channel. As the river meanders and changes course over time, it may abandon certain channels, leaving them as isolated features in the floodplain.

River terraces and abandoned channels are valuable geomorphic features that provide insights into past climate change, river behavior, and the evolution of river systems. They also serve as important habitats for various organisms.

River terraces are not formed by the deposition of sediment during floods. They are formed by the lateral migration of the river channel, which leaves behind abandoned floodplains that become elevated above the current river level.

Abandoned channels are not always associated with river terraces. They can occur independently, especially in areas where the river has undergone significant changes in its course or where avulsion has occurred.

Avulsion is the process by which a river abandons its channel and creates a new one. This can occur suddenly or gradually, and it can result in the formation of abandoned channels.

Changes in climate, sea level, and tectonic uplift can all contribute to the formation of river terraces. Climate change can alter the discharge and sediment load of a river, leading to changes in its erosional and depositional patterns. Changes in sea level can cause rivers to adjust their base level, resulting in the formation of terraces. Tectonic uplift can also cause rivers to downcut and form terraces.

While river terraces and abandoned channels can be used for agriculture and development, this is not a potential ecological significance. Their ecological significance lies in their role as habitats for aquatic organisms, their support for riparian vegetation, and their function as corridors for wildlife movement.

River terraces can provide valuable information about past climate conditions, river discharge and sediment load, and tectonic activity. By studying the elevation, morphology, and sediment composition of river terraces, geologists can reconstruct the history of a river's evolution and gain insights into past environmental changes.

Abandoned channels can be found in floodplains, deltas, alluvial fans, and other depositional environments associated with rivers. They are particularly common in areas where rivers have undergone significant changes in their course or where avulsion has occurred.

The study of river terraces and abandoned channels falls under fluvial geomorphology, which is the branch of geomorphology that focuses on the processes and landforms associated with rivers and streams.

Lacustrine terraces are not a common type of river terrace. They are associated with lakes rather than rivers.

Abandoned channels can serve as important groundwater recharge zones, wetlands, and wildlife corridors. They provide valuable habitat for a variety of aquatic and terrestrial organisms, and they can also play a role in flood control and water quality improvement.