Soil Erosion Types and Causes Questions and Answers

Answer: C

The match is P-3, Q-1, R-5, S-4, T-2.

• A flownet is drawn from streamlines and equipotential lines.
• The EI₃₀ index, storm energy times maximum 30-minute intensity, measures the erosivity of rainfall: soil erosion.
• Groynes are structures built out from a river bank to protect it.
• An isobath here is a line joining points of equal depth to groundwater.
• Runoff is estimated by the SCS curve number method.

The other options link the flownet to groundwater depth or the EI₃₀ index to the curve number, which misreads both terms.

Answer: C

Soil degradation takes place due to accelerated erosion.

Geologic (natural) erosion is the slow wearing of land by water, wind and gravity under natural vegetation; it is roughly balanced by soil formation. Accelerated erosion is erosion speeded up by human activity, such as deforestation, overgrazing and poor tillage, removing soil far faster than it forms. This is what degrades farmland.

Glacial erosion is the work of ice and is confined to glaciated mountains. Geologic erosion shapes landscapes over long periods without net degradation.

Answer: B

The removal of a thin, uniform top layer by overland flow is sheet erosion.

In sheet erosion, raindrop splash detaches soil and shallow overland flow carries it away more or less evenly over the field, so the topsoil thins without visible channels. It is the least noticeable form of water erosion but removes the most fertile layer.

Rill and gully erosion cut channels, and torrent erosion is channel erosion by fast mountain streams. Glacial erosion is caused by ice, not by overland flow.

Answer: C

Class IV land is partly suitable for cultivation.

In the USDA land capability classification used in India, Classes I to IV are suited to cultivation with increasing limitations, and Classes V to VIII are not suited to regular cultivation. Class IV land has very severe limitations, from steep slopes or erosion hazards, and can be cultivated only occasionally or with very careful management, so it is the last class that is partly suitable for cultivation.

'Suitable for cultivation' fits Classes I to III better. 'Not suitable for cultivation' describes Classes V to VIII.

Answer: B

A high intensity rain produces great splash.

Splash erosion depends on the kinetic energy of raindrops. High intensity storms have larger drops falling at higher terminal velocities, so their kinetic energy per unit of rain is greater. Each impact detaches and throws more soil, so splash increases with rainfall intensity. This is why the erosivity index EI₃₀ combines storm energy with intensity.

Less splash or no effect would mean intensity did not matter, which contradicts this relationship.

Answer: D

All three can deteriorate a watershed, so the answer is All above.

Rain falling on bare land and fires that strip vegetation leave the soil exposed to erosion. Industrial expansion clears land, seals surfaces and pollutes water. Unscientific mining and quarrying removes vegetation and topsoil, dumps loose spoil and silts up streams. Each reduces infiltration, increases runoff and sediment, and so degrades the watershed.

Picking only one of them ignores the others, which are equally recognised causes of watershed degradation.