Geomorphic Processes | Class 11 Geography Notes

Depositional Landforms

Depositional landforms formed by running water occur when the velocity of water decreases sufficiently to deposit the sediments it carries. These landforms include alluvial fans, deltas, floodplains, natural levees, point bars, and meanders.

Alluvial fans form when streams flowing from higher elevations enter a plain or foot slope with a gentle gradient. The coarse sediments carried by the stream are deposited as a broad, cone-shaped deposit. In humid areas, these fans have low cones with gentle slopes, while in arid and semi-arid regions, they appear as high cones with steep slopes.

Deltas form where rivers deposit their load at the mouth, spreading sediments into the sea. Unlike alluvial fans, delta deposits are well sorted with clear stratification; coarser materials settle first, while finer silts and clays are carried farther into the sea. The river distributaries lengthen as the delta grows.

Floodplains are flat areas adjacent to river channels, formed by deposition during floods. The active floodplain is the river bed itself, while the inactive floodplain lies above the banks and contains flood and channel deposits. Natural levees are raised ridges of coarse sediments along river banks, formed by deposition during floods. Point bars are depositional features on the inside bends of meanders, consisting of mixed sediment sizes deposited by slower water.

Meanders are sinuous bends in river channels formed due to lateral erosion and deposition on gentle slopes. They are not landforms but channel patterns. Meanders grow as erosion occurs on the outer (concave) bank and deposition on the inner (convex) bank. When a meander loop is cut off, it forms an oxbow lake.

📊 Diagram: Figure 6.3: An alluvial fan deposited by a hill stream on the way to Amarnath, Jammu and Kashmir; Figure 6.4 : A satellite view of part of Krishna river delta, Andhra Pradesh; Figure 6.5: Natural levee and point bars; Figure 6.6: A satellite scene showing meandering Burhi Gandak river near Muzaffarpur, Bihar, showing a number of oxbow lakes and cut-offs; Figure 6.7: Meander growth and cut-off loops and slip-off and undercut banks

🔗 Connection: This section transitions to the role of groundwater in landform evolution.