Water Logging and Reclamation MCQ Quiz in मराठी - Objective Question with Answer for Water Logging and Reclamation - मोफत PDF डाउनलोड करा

Explanation:

Waterlogging is a phenomenon in which the productivity of land gets affected due to the rise in the water table, thus leading to flooding of the root zone of the plants.

Causes of Water Logging:

• Over and intensive irrigation
• Seepage of water from adjoining high lands
• Seepage of water through the canals
• Impervious obstruction
• Inadequate Surface Drainage
• Submergence due to floods
• Excessive rains
• Irregular or flat topography

Control of Water Logging: 

• Lining of canals
• Crop rotation
• Efficient Drainage System
• Providing Intercepting drains
• Lift Irrigation

Concept:

Tile drainage is a type of drainage system that removes excess water from soil below the surface. Plants need air as well as moisture in their root zones for their survival, excess irrigation farm water is free to move into the underground tile drains, this water, if not removed, retards the plant growth because It fills the soil voids and restricts proper aeration, Therefore there is a need for Sub-surface drainage or tile drainage.

The spacing of the drains is given by:

\(S = \frac{{4k}}{q}\left( {{b^2} - {a^2}} \right)\)

Where,

k = Coefficient of permeability

q = discharge per unit length in the drain

a = depth of the impervious strata below the drain

b = maximum height of the drained water table above the impervious layer

Therefore,

Explanation

SAR of 12 represents Medium Sodium Water

Sodium-ion in small amounts is good for plants. But excess sodium ion creates the problem for both plant and soil. Excess sodium contributes to salinity and it is toxic for some sensitive crops.

Soil with high sodium content becomes very plastic in nature in the wet stage, which shows low permeability and poor aeration.

This excessiveness of sodium ion is measured in terms of sodium absorption ratio (SAR).

\({\rm{SAR}} = \frac{{\left[ {{\rm{N}}{{\rm{a}}^ + }} \right]}}{{\sqrt {\frac{{\left[ {{\rm{C}}{{\rm{a}}^{2 + }}} \right] + \left[ {{\rm{M}}{{\rm{g}}^{2 + }}} \right]}}{2}} }}\)

Where,

[Na+] = concentration of sodium ion in milli-equivalent per liter

[Ca2+] = concentration of calcium ion in milli-equivalent per liter

[Mg2+] = concentration of magnesium ion in milli-equivalent per liter

Explanation

Sodium-ion in small amounts is good for plants. But excess sodium ion creates the problem for both plant and soil. Excess sodium contributes to salinity and is toxic for some sensitive crops.

Soil with high sodium content becomes very plastic in nature in the wet stage, which shows low permeability and poor aeration.

This excessiveness of sodium ion is measured in terms of sodium absorption ratio (SAR).

\({\rm{SAR}} = \frac{{\left[ {{\rm{N}}{{\rm{a}}^ + }} \right]}}{{\sqrt {\frac{{\left[ {{\rm{C}}{{\rm{a}}^{2 + }}} \right] + \left[ {{\rm{M}}{{\rm{g}}^{2 + }}} \right]}}{2}} }}\)

Where,

[Na+] = concentration of sodium ion in milli-equivalent per liter

[Ca2+] = concentration of calcium ion in milli-equivalent per liter

[Mg2+] = concentration of magnesium ion in milli-equivalent per liter

SAR = \(\frac{{{\rm{Na}^{+}}}}{{\sqrt {\frac{{{\rm{Ca}^{++}} + {\rm{Mg}^{++}}}}{2}} }}\) = \(\frac{{28}}{{\sqrt {\frac{{12 + 20}}{2}} }} = 7\)

Important Points

SAR - [0 - 10] (Type of water is Low sodium)

Concept:

The drainage coefficient is defined as the depth of water to be removed in 24 hours from the entire drainage area.

• It is used for the design of drainage systems for agricultural lands.
• In agricultural lands, open ditches or drains are the most commonly used surface drainage structures.
• The rate at which the open drains should remove water from a drainage area depends on:
  • Rainfall 
  • Size of the drainage area
  • Characteristics of the drainage area
  • Nature of the crops grown
  • The degree of protection required for them from waterlogging

​Calculation:

Given:

Drainage coefficient = 1.25 cm/day

Area = 12 ha = 120000 m² 

( 1 ha = 10000 m² )

Water removal period = 2 days

The volume of water removed = Drainage coefficient × Area × Time = (1.25/100) × 120000 × 2 = 3000 m³

In agricultural land, when the soil pores within the root zone of the crops get saturated with the subsoil water, the air circulation within the soil pores gets totally stopped, this phenomenon is termed as waterlogging.

The waterlogging makes the soil alkaline in character and the fertility of the land is totally destroyed and the yield of the crop is reduced.

Causes of waterlogging:

1) Over-irrigation, 

2) Seepage from canals, 

3) Inadequate surface drainage, 

4) Obstruction in a natural watercourse, 

5) Obstruction in subsoil drainage, 

6) Nature of soil, 

7) Incorrect method of cultivation, 

8) Seepage from the reservoir, 

9) Poor irrigation management, 

10) Excessive rainfall, 

11) The topography of the land, and

12) Occasional Flood

Remedial measures adopted for the prevention of waterlogging are:

1. Efficient surface drainage, 

2. Under - drainage by tie drains, 

3. Reducing Percolation from canals, 

4. Restriction of Irrigation, 

5. The lining of water resources, 

6. Removing obstruction in natural drainage, 

7. Prevention of seepage from water reservoirs, 

8. Depletion of groundwater storage by pumping, 

9. Changes in crop patterns, and 

10. Adoption of the sprinkler method for irrigation.

Concept:

Waterlogging:

• Waterlogging occurs when there is too much water in a plant’s root zone, which decreases the oxygen available to roots and Capillary fringe reaches the root zone of the plant.
• Waterlogging can be a major constraint to plant growth and production and, under certain conditions, will cause plant death.
• This constraint may not be apparent until the whole soil profile is saturated and water appears on the surface.
• The department provides landholders with technical information and support on management options to recognize and reduce the impacts of waterlogging.

Causes of waterlogging:

1) Over-irrigation

2) Seepage from canals

3) Inadequate surface drainage

4) Obstruction in a natural watercourse 

5) Obstruction in subsoil drainage 

6) Incorrect method of cultivation 

Remedial measures adopted for the prevention of waterlogging are:

1. Efficient surface drainage 

2. Under-drainage by tie drains 

3. Reducing Percolation from canals 

4. Restriction of Irrigation

5. The lining of water resources 

6. Removing obstruction in natural drainage 

7. Prevention of seepage from water reservoirs

Concept:

Waterlogging:

Waterlogging is the saturation of soil with water. Soil may be regarded as waterlogged when it is nearly saturated with water much of the time. ​It can happen when the water table rises to the extent that the soil pores in the crop root zone. The result is a restriction in the normal supply of air in the soil, a decline in the levels of oxygen, and an increase in the levels of carbon dioxide and ethylene.

Causes of Waterlogging:

• Inadequate drainage of over-land run-off increases the rate of percolation and in turn, helps in raising the water table.
• The water from rivers may infiltrate into the soil.
• Seepage of water from earthen canals also adds a significant quantity of water to the underground reservoir continuously.
• Irrigation water is used to flood the fields. If it is used in excess it may help appreciably in raising the water table. Good drainage facility is very essential.

Effects of Waterlogging:

• Creation of Anaerobic Condition in the Crop Root-Zone.

• Growth of Water Loving Wild Plants.

• Falling of soil temperature

• Accumulation of Harmful Salts

Preventive Measures:

• Controlling the loss of water due to seepage from the canals.

• By lowering the FSL of the canal.

• By lining the canal section.

• By introducing intercepting drains.

Explanation:

• Tile drainage is a type of drainage system that removes excess water from soil below the surface.
• Plants need air as well as moisture in their root zones for their survival, excess irrigation farm water is free to move into underground tile drains.
• This water if not removed retards the plant growth because it fills the soil voids and restricts proper aeration, therefore there is a need for sub-surface drainage or tile drainage.

Spacing of the tile drainage is given by,

\(S = \frac{{4K}}{q}\left( {{b^2} - {a^2}} \right)\)

Where K = Coefficient of permeability

q = Discharge per unit length in the drain

a = Depth of the impervious strata below the drain

b = Maximum height of the drained water table above the impervious layer.

So, from the above equation, it is clear that spacing of tile drains to relieve water-logged land is directly proportional to the coefficient of permeability of the soil to be drained

Explanation:

Saline and Alkali Soil:

When the Chloride (Cl-), Sulphate (SO42-), Carbonate (CO32-), and Bicarbonate (HCO32-) salts of Sodium (Na+), Calcium (Ca2+), and Magnesium (Mg2+) are increased in soil, the soil becomes saline and alkali. On the basis of the amount of salts, average quantity of exchangeable sodium, and pH, such soils are classified as saline, alkali, and saline-alkali soils. Saline and alkaline soils occur in areas having little rainfall (more than areas of desert soils). They are known by various names, namely Reh, Kallar, Usar, Thur, Rakar, Karl, and Chopan.

Saline Soil or White Alkali Soil:

• Commonly formed in arid and semi-arid regions having rainfall less than 55 cm.
• A high toxic concentration of soluble salts is present in the rootzone.
• It is also called Solonchak soil.
• The soluble salts are Cl- and SO42- of Na, Ca2+, and Mg2+.
• The electrical conductivity (EC) of soil solution saturated extract is more than 4.0 dS/m at 25°C, ESP is < 15%, and pH is < 8.5.
• Lots of salts are deposited on the soil surface in saline soils and the saline soil layer shines white in the dry season.

Sodic Soil or Black Alkali/Non-Saline Alkali:

• High exchangeable sodium percentage interferes with plant growth.
• EC < 4.0 dS/m at 25°C b) ESP > 15%.
• pH > 8.5 (8.5 - 10.0)
• Low infiltration rate.
• Also called solonetz soil.
• Occurrence in Indo-Gangetic plains of UP, Punjab, and Haryana.
• Replace exchangeable Na+ with Ca++ and thus released Na+ salt be leached out of the rootzone.