Write a list of work of water/ River
Land forms?
Answers
Answer:
Landforms across different river courses.
Explanation:
Upper course Middle course Lower course
V-shaped valley Meanders Braiding
Interlocking spurs Ox-bow lakes Deltas
Waterfalls and rapids Gentle gradients Estuary
Steep gradients Flat land
Waterfalls - ...
Rapids - ...
Meanders - ...
Oxbow lakes - ...
Braided channel - ...
Floodplains - ...
Levees -
Explanation:
Landforms are categorised by characteristic physical attributes such as elevation, slope, orientation, rock exposure, and soil type.
Potholes:
These are the deep natural underground cave formed by the erosion of rock, especially by the action of water
These currents erode the river’s bed and create small depressions in it.
These are drilled into the bed of a river and are cylindrical in nature.
The diameter and depth varies from few centimetres to meters.
These are formed due to the whirling impact of the water current in the upper course of the river.
In India, the potholes can be observed in the river bed of the Kukadi, Krishna and Godavari river in Maharashtra.
A representational picture is given below :
V-Shaped valley:
In mountain ranges, you will find these types of valleys
V-shaped valleys have steep valley walls with narrow valley floors
V-Shaped valleys are deep river valleys with steep sides that look like a letter V, a diagram shown below will give you a better understanding
These are generally formed by the result of erosion and withering by fast-flowing rivers and are generally formed in the upper course of the river.
A deep and narrow valley with steep sides is called a Gorge.
Many gorge are found in river Ulhas in Thane district in Maharashtra and the gorge of the river Narmada at Bhedaghat near Jabalpur in Madhya Pradesh are well known.
Waterfalls (Geological):
Waterfalls are formed due to erosion of both hard rock and soft rock.
As the river flows over the resistant rock, it falls onto the less resistant rock, eroding it and creating a greater height difference between the two rock types, producing the waterfall.
Over thousands of years, the repeated collapse of the caprock and retreat of the waterfall produces a gorge of recession.
Waterfalls exist because of the difference in rock types. When a river flows, it passes through many different rock types and when a river passes from a resistant rock bed to a softer one, it erodes softer one very quickly and at the junction between the rock types, it steepens its gradient.
The highest waterfall in the world is Angel Falls in Venezuela (~800 m).
The largest waterfall is the Chutes de Khone (Khone Falls) on the Mekong River in Laos.
The Niagara Falls on the river Niagara and Jog falls in Karnataka on Sharavathi river are famous waterfalls.
Meanders and Ox-bow lakes:
Meanders are bends in a river that form as a river’s sinuosity increases.
A meander forms when moving water in a stream erodes the outer banks and widens its valley, and the inner part of the river has less energy and deposits silt.
Meanders form a snake-like pattern as the river flows across a fairly flat valley floor.
The sinuosity of a river is a measurement of how much a river varies from a straight line.
Meanders are formed due to lateral erosion and as the erosion increases over the period of time, the meanders in the river again start flowing in the straight line.
Meanders formation is a self-intensifying process where a greater curvature results in more erosion of the bank which in turn results in greater curvature.
Oxbow lakes are an evolution of meanders that undergo extensive deposition and erosion
When the meanders cut from the main course and water accumulates in this pool then it resembles the shape of the oxbow.
Fan-shaped plains:
These are formed in the region where the Tributaries Rivers joins the main river.
These are formed due to the deposition of material carried by the Tributaries Rivers.
These flows come from a single point source at the apex of the fan, and over time move to occupy many positions on the fan surface.
This deposition resembles the shape a Fan like plains
Flood Plains:
These are formed due to the overflows of the river and flood in the nearby areas.
It is an area of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding.
Floodplains are made by downstream travelling meanders.
Slit carried by the water gets deposited in flooded areas and formed flat plains on both sides of river.
The Gangetic plain is a flood plain.
Levees:
It is an embankment built to prevent the overflow of a river by a ridge of sediment deposited naturally alongside a river by overflowing water.
When a river floods, it deposits its load over the flood plain due to a dramatic drop in the river’s velocity as friction increases greatly.
Repeated floods cause the mounds to build up