Describe the cross profile of a lower course?

In the lower course of a river, the cross-profile is generally characterized by a wide, shallow channel with gentle bank slopes. Here are some key features of the cross-profile of a lower course:

1. Wide Channel: The river channel in the lower course is typically wider compared to the upper course. This is because the erosive power of the river decreases as it reaches the lower gradient areas, resulting in the deposition of sediments and widening of the channel.

2. Gentle Bank Slopes: The banks of the river in the lower course are usually less steep compared to those in the upper course. This is due to the reduced erosive energy and increased sediment deposition, which leads to the formation of gentler slopes.

3. Floodplains: In the lower course, the river often develops floodplains. Floodplains are low-lying areas adjacent to the river that are prone to flooding during high water levels. These areas are formed by the deposition of sediments during overbank flooding events.

4. Meandering: Lower course rivers often exhibit meandering patterns. Meanders are sinuous bends in the river's course that are formed due to variations in flow velocity and sediment deposition. As the river flows through these meanders, the outer banks experience erosion, while sediment deposition occurs on the inner banks.

5. Deposition of Sediments: The lower course of a river is characterized by significant sediment deposition. This is because the river loses its erosive power as it reaches flatter areas, allowing the suspended sediments to settle down. As a result, the riverbed and the surrounding areas are built up by layers of deposited sediments.

6. Terraces: In some lower course rivers, terraces can be observed. Terraces are remnants of former floodplains that have been uplifted or abandoned due to changes in the river's course or variations in water levels over time.

7. Levees: Levees are natural embankments that are formed along the riverbanks in the lower course. They are built up from the deposition of sediments during periods of flooding. Levees help to confine the river's flow and prevent it from spilling over into the surrounding floodplains.

Overall, the cross-profile of a lower course river is characterized by a wide channel, gentle bank slopes, floodplains, meandering patterns, sediment deposition, terraces, and levees. These features reflect the reduced erosive energy and increased sediment deposition that occur in the lower reaches of a river system.