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Past Questions — 2025
What does Dicken’s formula estimate?
A)
The rainfall intensity
B)
The peak flood discharge in a catchment
C)
The evaporation rate
D)
The infiltration rate
Dickens' formula is an empirical formula used in hydrology to estimate the peak flood discharge (Q) of a catchment area. The formula is expressed as Q = C * A^(3/4), where 'Q' is the peak discharge, 'C' is Dickens' coefficient (which varies based on the region and catchment characteristics), and 'A' is the catchment area.
Analysis of options:
- Option (a) Rainfall intensity is typically measured using rain gauges or estimated via Intensity-Duration-Frequency (IDF) curves.
- Option (b) is correct as Dickens' formula specifically relates catchment area to peak flood discharge.
- Option (c) Evaporation rate is measured using evaporation pans or calculated via Penman's equation.
- Option (d) Infiltration rate is measured using infiltrometers or estimated via Horton's equation.
Which method is NOT a technique of contouring?
A)
Direct method
B)
Indirect method
C)
Compass method
D)
Grid method
Contouring is the process of determining the layout of a surface by joining points of equal elevation. There are two primary techniques used for contouring:
1. Direct Method: In this method, the points on the contour are located directly in the field using a level and a staff. It is highly accurate but very time-consuming.
2. Indirect Method: In this method, the elevations of a set of points are determined first, and the contours are then interpolated between these points. Common techniques under the indirect method include:
- Grid Method (or Square Method): The area is divided into a grid of squares, and elevations are taken at the corners.
- Radial Line Method: Elevations are taken along lines radiating from a central point.
- Cross-section Method: Elevations are taken along perpendicular sections.
Compass method is a technique used for traversing and determining the horizontal directions (bearings) of lines to map the boundaries or features of an area; it does not measure vertical elevations and therefore is not a technique for contouring.
What is a major disadvantage of surface drainage?
A)
Expensive initial installation
B)
Soil erosion due to rapid water removal
C)
High labor costs
D)
Inability to handle excess water
Surface drainage involves the removal of excess water from the land surface through open ditches, channels, or land grading.
1. Why Option (b) is correct: Because surface drainage relies on the movement of water across the top of the soil, it increases the velocity of runoff. High-velocity surface runoff carries away topsoil particles, leading to significant soil erosion, especially on sloped terrains. This is the primary environmental and agricultural disadvantage of surface drainage compared to subsurface (tile) drainage.
2. Why Option (a) is incorrect: Surface drainage is generally cheaper to install than subsurface drainage because it does not require expensive perforated pipes or specialized trenching machinery.
3. Why Option (c) is incorrect: While labor is required for digging ditches, the overall cost is typically lower than the technical installation and maintenance of complex underground systems.
4. Why Option (d) is incorrect: Surface drainage is specifically designed to handle excess water (surface ponding); therefore, the inability to handle water is not a characteristic disadvantage, but rather the purpose of the system.
Which factor affects groundwater movement?
A)
Soil permeability
B)
Temperature variations
C)
Humidity levels
D)
Atmospheric pressure
Groundwater movement is governed by Darcy's Law, which states that the flow rate (discharge) is proportional to the hydraulic gradient and the hydraulic conductivity of the medium.
1. **Soil Permeability (Hydraulic Conductivity):** This is the measure of the ability of a porous medium (soil or rock) to allow fluids to pass through it. High permeability (e.g., in sand or gravel) allows water to move quickly, while low permeability (e.g., in clay) restricts movement. Therefore, it is a primary factor affecting groundwater movement.
2. **Temperature variations (Option b):** While temperature can slightly affect the viscosity of water, it is not a primary driver or controlling factor of groundwater movement compared to the geological properties of the aquifer.
3. **Humidity levels (Option c):** Humidity refers to the moisture content in the air. While it affects evapotranspiration at the surface, it does not directly control the movement of water within saturated underground aquifers.
4. **Atmospheric pressure (Option d):** While atmospheric pressure acts on the water table, the pressure gradients within the aquifer (hydraulic head) are the dominant drivers of flow, not the ambient air pressure.
Which of the following factors does NOT influence canal alignment?
A)
Topography of the region
B)
Type of soil
C)
Number of people in the command area
D)
Availability of cross-drainage structures
Canal alignment refers to the layout of the centerline of a canal on the ground. The primary objective is to convey water from the source to the command area with minimum cost and maximum efficiency.
1. Topography of the region (Option a): This is a critical factor. The alignment is usually decided based on the contours of the land to ensure gravity flow and minimize expensive excavation or embankments.
2. Type of soil (Option b): Soil permeability and stability influence alignment. For example, canals are avoided in highly permeable sandy soils to prevent seepage losses, or in unstable soils to prevent breaches.
3. Availability of cross-drainage structures (Option d): The alignment is planned to minimize the number of crossings with natural drains (rivers, streams) to reduce the cost and complexity of constructing aqueducts, super-passages, or siphons.
In contrast, the 'Number of people in the command area' (Option c) relates to the socio-economic demand and the capacity (discharge) of the canal, but it does not dictate the physical path (alignment) the canal takes across the terrain. The alignment is determined by physical, geological, and engineering constraints, not by the population count.
Which of the following is NOT an effect of waterlogging?
A)
Reduced soil aeration
B)
Enhanced root respiration
C)
Increased salinity levels
D)
Stunted plant growth
Waterlogging occurs when the soil becomes saturated with water, filling the pore spaces that would normally contain air.
1. **Reduced soil aeration (Option a):** This is a direct effect of waterlogging. When water fills the soil pores, oxygen is displaced, leading to anaerobic conditions.
2. **Enhanced root respiration (Option b):** This is INCORRECT. Root respiration requires oxygen. In waterlogged soils, the lack of oxygen (hypoxia or anoxia) severely inhibits root respiration, forcing plants to switch to less efficient anaerobic fermentation, which can lead to the buildup of toxic ethanol and a lack of energy (ATP) for the plant.
3. **Increased salinity levels (Option c):** This is a common effect. Waterlogging often leads to a rise in the water table, which brings dissolved salts from deeper soil layers to the surface via capillary action. As the water evaporates, these salts accumulate in the root zone.
4. **Stunted plant growth (Option d):** This is a direct consequence. Due to the lack of oxygen for respiration and the potential increase in salinity or toxicity (e.g., manganese or iron toxicity), the roots cannot function properly, leading to nutrient deficiencies and stunted overall growth.
Therefore, since the question asks which is NOT an effect, 'Enhanced root respiration' is the correct answer because waterlogging actually suppresses root respiration.
How does drip irrigation help in reducing field irrigation requirement?
A)
By minimizing runoff
B)
By increasing infiltration
C)
By delivering water directly to the root zone
D)
All of the above
Drip irrigation (also known as trickle irrigation) is a highly efficient method of irrigation that reduces the overall field irrigation requirement through several mechanisms:
1. **Delivering water directly to the root zone (Option c):** This is the primary mechanism. By applying water precisely where the plant needs it, water waste in non-cropped areas is eliminated, significantly reducing the total volume of water required.
2. **Minimizing runoff (Option a):** Because water is applied at a very low rate (drop by drop), the application rate is typically lower than the soil's infiltration rate. This prevents surface ponding and subsequent runoff, ensuring almost all applied water enters the soil profile.
3. **Increasing infiltration efficiency (Option b):** While 'increasing infiltration' in a general sense might seem vague, in the context of irrigation efficiency, drip systems ensure that water infiltrates the soil precisely and steadily, reducing deep percolation losses (water sinking below the root zone) compared to flood irrigation.
Since all three factors contribute to the reduction of the total field irrigation requirement, the correct answer is 'All of the above'.
What is the most effective method to detect waterlogging?
A)
Checking soil color
B)
Measuring soil moisture content
C)
Observing plant height
D)
Measuring wind velocity
Waterlogging occurs when the soil is saturated with water, leading to anaerobic (oxygen-poor) conditions. Under these conditions, chemical reduction occurs: iron (Fe3+) is reduced to ferrous iron (Fe2+), which reacts with other minerals to create a characteristic 'gleying' effect. This results in the soil turning grey, bluish, or greenish-grey. This change in soil color is a definitive and widely used indicator for detecting long-term waterlogging and poor drainage.
Why other options are incorrect:
- b. Measuring soil moisture content: While this tells you how much water is present at a specific moment, it does not necessarily indicate 'waterlogging' (a systemic drainage failure) as moisture levels fluctuate daily due to irrigation or rain.
- c. Observing plant height: Stunted growth can be a symptom of waterlogging, but it is non-specific; plants can be short due to nutrient deficiency, pests, or poor seed quality.
- d. Measuring wind velocity: Wind velocity affects evaporation rates but is not a method to detect the presence of waterlogging in the soil profile.
A “benchmark” in surveying is used to measure-
A)
Horizontal distances
B)
Vertical elevations
C)
Magnetic north
D)
The width of a structure
In surveying, a Benchmark (BM) is a permanent point of known elevation above or below a fixed reference datum (such as Mean Sea Level). It serves as a starting point or a reference point for determining the elevations of other points in a survey area through a process called leveling.
- Option (a) is incorrect because horizontal distances are measured using tapes, chains, or EDM (Electronic Distance Measurement) instruments.
- Option (c) is incorrect because magnetic north is determined using a compass.
- Option (d) is incorrect because the width of a structure is a linear horizontal measurement, not a reference elevation.
What is the primary focus of hydrology?
A)
Study of ocean currents
B)
Study of groundwater only
C)
Study of movement, distribution, and quality of water on Earth
D)
Study of air pressure and weather patterns
Hydrology is defined as the science that deals with the occurrence, circulation, distribution, and properties of water on Earth and its atmosphere. This includes the study of the hydrological cycle (precipitation, evaporation, transpiration, runoff, and infiltration), surface water (rivers, lakes), and groundwater.
Analysis of other options:
- Option (a) refers to Oceanography, which is a specific branch of earth science focusing on the oceans.
- Option (b) refers to Hydrogeology, which is a sub-discipline of hydrology focusing specifically on groundwater; however, hydrology as a whole is broader.
- Option (d) refers to Meteorology, which is the study of the atmosphere and weather patterns.
Which of the following is NOT a type of canal alignment?
A)
Watershed canal
B)
Contour canal
C)
Side slope canal
D)
Lateral canal
In canal engineering, 'alignment' refers to the path or route the canal follows relative to the topography of the land.
1. Watershed Canal (Option a): A canal aligned along the ridge line (watershed) of the area. It allows irrigation on both sides of the canal by gravity.
2. Contour Canal (Option b): A canal aligned approximately parallel to the contours of the country. It is used when the land slopes gently in one direction.
3. Lateral Canal (Option d): While often categorized by function, in the context of alignment and distribution networks, laterals are branches that take off from the main canal to deliver water to specific fields, following a specific alignment relative to the main canal.
'Side slope' (Option c) is a geometric property of the canal cross-section (the ratio of horizontal distance to vertical distance of the bank), not a type of alignment. Therefore, a 'Side slope canal' is not a recognized term for a type of canal alignment.
What is the significance of the Base Period of a crop?
A)
It determines the time between sowing and harvesting
B)
It is the total period from first to last irrigation
C)
It defines the period of highest water demand in a crop cycle
D)
It represents the time taken for root development
In Irrigation Engineering, the 'Base Period' (B) is formally defined as the time elapsed between the first watering of a crop and the last watering of that crop. It is a critical parameter used to calculate the 'Delta' (total depth of water required by a crop) and the 'Duty' of water.
Analysis of options:
- Option (a) is incorrect because the time between sowing and harvesting is known as the 'Crop Period'. The base period is usually shorter than the crop period because irrigation is not required immediately after sowing or immediately before harvesting.
- Option (b) is correct as it aligns with the standard technical definition of Base Period.
- Option (c) is incorrect because the period of highest water demand is referred to as the 'Critical Period' of the crop.
- Option (d) is incorrect as root development is a biological growth phase and does not define the irrigation scheduling period known as the base period.
What is the primary advantage of using lined canals over unlined canals?
A)
Increased seepage losses
B)
Reduced seepage losses and increased efficiency
C)
Easier maintenance of canal embankments
D)
Reduced flow velocity
In canal engineering, lining refers to the provision of an impermeable layer (such as concrete, bricks, or plastic membranes) on the wetted perimeter of the canal.
1. **Seepage Control**: The primary purpose of lining is to prevent water from percolating into the ground (seepage). Unlined canals lose a significant volume of water to the soil, whereas lined canals drastically reduce these losses.
2. **Efficiency**: By reducing seepage, more water reaches the intended command area, thereby increasing the overall conveyance efficiency of the irrigation system.
3. **Velocity**: Lining reduces the roughness coefficient (Manning's n) of the canal bed, which actually allows for a higher flow velocity compared to unlined canals, preventing the deposition of silt.
Analysis of other options:
- Option (a) is incorrect because lining decreases seepage losses, not increases them.
- Option (c) is a secondary benefit (lining prevents weed growth and erosion), but the 'primary' advantage is water conservation (seepage reduction).
- Option (d) is incorrect because lining typically increases flow velocity due to a smoother surface.
Using Dicken’s formula, estimate the peak discharge if the catchment area is 500 km² and the Dicken’s coefficient (C) is 25.
A)
1565 m³/s
B)
2643 m³/s
C)
2547 m³/s
D)
3070 m³/s
Option B is correct: 2643 m³/s.
Which of the following factors has the most direct and immediate impact on runoff generation?
A)
Land slope
B)
Soil type
C)
Vegetation cover
D)
Rainfall intensity
Runoff generation is governed by the relationship between the rate at which water is supplied to the surface and the rate at which the surface can absorb it.
1. **Rainfall Intensity (Correct):** This is the most direct and immediate trigger. According to the concept of 'Horton Overland Flow', runoff occurs when the rainfall intensity exceeds the infiltration capacity of the soil. If the intensity is low, most water infiltrates; if it is high, runoff is generated immediately, regardless of other factors.
2. **Land Slope (Incorrect):** While slope affects the velocity of runoff and helps move water quickly to channels, it is a static characteristic. It influences the *efficiency* of runoff but does not 'trigger' the generation of runoff in the same immediate way as rainfall intensity.
3. **Soil Type (Incorrect):** Soil type determines the infiltration capacity (e.g., sandy soil vs. clay soil). While it sets the threshold for how much rain is needed to cause runoff, it is a constant property of the site and not the immediate cause of a specific runoff event.
4. **Vegetation Cover (Incorrect):** Vegetation intercepts rainfall and increases infiltration by improving soil structure. Like soil type, it is a modulating factor that influences the amount of runoff, but it is not the direct driver of the runoff process itself.
In summary, while options a, b, and c are critical parameters that define the 'catchment characteristics', rainfall intensity is the 'forcing function' that directly and immediately initiates runoff generation.
Which factor is most important when designing a drainage system layout?
A)
Soil type and permeability
B)
Color of the soil
C)
Plant height in the previous season
D)
The amount of fertilizers used
In agricultural drainage design, the primary goal is to remove excess water from the soil profile to maintain aerobic conditions for plant roots. The efficiency of water removal depends directly on the hydraulic conductivity (permeability) of the soil. Soil type (e.g., sandy, loamy, or clayey) determines how quickly water moves toward the drains. For instance, sandy soils have high permeability and require wider drain spacing, whereas clay soils have low permeability and require closer spacing to effectively lower the water table.
Other options are incorrect because:
- (b) Color of the soil: While soil color can indicate drainage conditions (e.g., gray/gleyed colors indicate poor drainage), it is a symptom, not a design factor used to calculate drain spacing or layout.
- (c) Plant height in the previous season: This is a biological outcome and does not influence the physical engineering requirements of a drainage system.
- (d) The amount of fertilizers used: Fertilizer application is a nutrient management practice and does not dictate the physical layout or hydraulic capacity of a drainage system.
Why is it essential to conduct levelling before constructing a highway?
A)
To determine the exact quantity of cement required
B)
To establish the correct elevation and drainage slopes
C)
To identify underground water sources
D)
To check soil fertility
Levelling is a fundamental surveying operation used to determine the relative heights (elevations) of points on the earth's surface. In highway construction, it is essential for two primary reasons: 1) Elevation: To design the vertical alignment (gradients) of the road to ensure it is safe for vehicles and minimizes the volume of earthwork (cutting and filling). 2) Drainage: Proper slopes (camber and longitudinal gradient) must be established to ensure that rainwater drains off the road surface quickly, preventing hydroplaning and protecting the pavement structure from water damage.
Why other options are incorrect:
- Option (a): Cement quantity is determined by the structural design and volume of the pavement, not by levelling.
- Option (c): Identifying underground water sources requires geophysical surveys or borehole drilling, not surface levelling.
- Option (d): Soil fertility is a concern for agriculture and is determined through soil sampling and laboratory analysis, not surveying.
Calculate the intensity of irrigation if the Gross Command Area (GCA) is 5000 hectares and the Culturable Command Area (CCA) is 4000 hectares.
A)
80%
B)
75%
C)
85%
D)
90%
Step-by-step calculation:
1. **Definitions**:
- **Gross Command Area (GCA)**: The total area that can be irrigated by a canal system, including forests, roads, villages, and wasteland.
- **Culturable Command Area (CCA)**: The portion of the GCA that is actually fit for cultivation.
- **Intensity of Irrigation**: This is defined as the ratio of the area actually irrigated to the Culturable Command Area (CCA), expressed as a percentage. However, in many standard textbook problems where the 'area actually irrigated' is not explicitly given separately from the CCA, the intensity of irrigation is calculated as the ratio of CCA to GCA to determine the proportion of the total command area that is cultivable.
2. **Formula**:
Intensity of Irrigation (%) = (CCA / GCA) × 100
3. **Substitution**:
Given GCA = 5000 hectares
Given CCA = 4000 hectares
Intensity = (4000 / 5000) × 100
Intensity = 0.8 × 100 = 80%
Therefore, the intensity of irrigation is 80%. Option (a) is correct, while options (b), (c), and (d) are mathematically incorrect based on the provided data.
Why is it important to consider the “Critical Velocity Ratio” in canal design?
A)
It determines whether the canal will experience erosion or sediment deposition
B)
It ensures that the water flows at the highest possible velocity
C)
It is used to calculate the amount of water required for irrigation
D)
It helps in increasing the depth of water in the canal
In canal engineering, the design must balance two opposing hydraulic phenomena: silting and scouring.
1. **Non-silting Velocity:** This is the minimum velocity required to keep the sediment in the water in suspension so that it does not settle at the bottom of the canal (deposition).
2. **Non-scouring Velocity:** This is the maximum velocity that the canal bed and banks can withstand without the soil particles being washed away (erosion).
The 'Critical Velocity Ratio' (often associated with the concept of the regime velocity or the ratio between actual velocity and critical velocity) is used to ensure that the actual velocity of flow falls between the non-silting and non-scouring limits.
- If the velocity is too low (below the critical silting velocity), sediment deposition occurs, reducing the canal's carrying capacity.
- If the velocity is too high (above the critical scouring velocity), erosion occurs, damaging the canal structure.
Therefore, option (a) is correct. Option (b) is incorrect because the highest possible velocity would cause scouring. Option (c) refers to water demand/duty, not velocity ratios. Option (d) refers to the hydraulic geometry, not the velocity ratio.
What is the primary benefit of using GPS in surveying?
A)
It eliminates the need for fieldwork
B)
It provides high-accuracy elevation measurements
C)
It allows real-time positioning with minimal effort
D)
It replaces all traditional surveying techniques
GPS (Global Positioning System) provides the coordinates (latitude, longitude, and altitude) of a point on Earth by receiving signals from satellites.
1. Why Option (c) is correct: The primary advantage of GPS in surveying is the ability to obtain precise positioning data in real-time (RTK - Real Time Kinematic) without the need for manual chaining, sighting, or complex triangulation between points, which significantly reduces the physical effort and time required for field data collection.
2. Why Option (a) is incorrect: GPS does not eliminate fieldwork; a surveyor must still physically go to the site to place the GPS receiver on the specific point being measured.
3. Why Option (b) is incorrect: While GPS provides elevation (Z-coordinate), it is generally less accurate for vertical measurements compared to traditional leveling techniques (like using a digital level or total station) due to the geometry of the satellite constellation.
4. Why Option (d) is incorrect: GPS complements traditional techniques but does not replace them. For example, in dense forests or urban canyons (where satellite signals are blocked), traditional surveying methods like Total Station or Theodolite are still essential.
A farmer installs a drainage system, but over time, its efficiency decreases. What could be the most likely reason?
A)
The soil structure has improved naturally
B)
The drainage system has become clogged with sediments
C)
The drainage system is working better than before
D)
The field has become more fertile
Step-by-step reasoning: 1. The question asks for the most likely reason why a drainage system's efficiency decreases over time. 2. Drainage efficiency refers to the ability of the system to remove excess water from the soil profile. 3. Option (b) describes 'clogging with sediments' (also known as siltation). In agricultural drainage, fine soil particles, organic matter, or mineral precipitates can accumulate inside the drainage pipes or tiles, restricting the flow of water and reducing the system's capacity to drain the field. 4. Option (a) is incorrect because improved soil structure generally enhances natural permeability and would not cause a man-made drainage system to lose efficiency. 5. Option (c) contradicts the premise of the question (efficiency is decreasing, not increasing). 6. Option (d) is incorrect because soil fertility relates to nutrient content and does not directly cause the mechanical failure or efficiency loss of a physical drainage installation.
What is the major disadvantage of side slope canals?
A)
High construction cost
B)
Excessive water loss due to seepage
C)
Prone to landslides and slope instability
D)
Requires pumping stations
In canal engineering, 'side slope canals' (referring to canals with sloping sides rather than vertical walls) have a significantly larger wetted perimeter compared to vertical-walled canals of the same cross-sectional area. The wetted perimeter is the surface area of the canal bed and sides that is in direct contact with the water. Since seepage loss is directly proportional to the wetted perimeter and the permeability of the soil, canals with side slopes experience much higher rates of water loss through infiltration into the surrounding ground.
Analysis of other options:
- (a) High construction cost: Generally, side slope canals are cheaper to construct than vertical walls (which require expensive reinforced concrete or retaining structures).
- (c) Prone to landslides: While slope stability is a design consideration, it is a failure mode rather than a general 'major disadvantage' inherent to the concept of side slopes; in fact, side slopes are used specifically to prevent the collapse that would occur with vertical cuts in loose soil.
- (d) Requires pumping stations: Pumping stations are required based on the topography and the need to lift water, regardless of whether the canal sides are sloped or vertical.
Which factor affects the selection of Manning’s coefficient for a canal?
A)
Water temperature
B)
Roughness of the canal bed and side slopes
C)
Water depth only
D)
Shape of the canal
Manning's equation is used to calculate the velocity of water in open channels. The formula is V = (1/n) * R^(2/3) * S^(1/2), where 'n' is Manning's roughness coefficient.
1. **Manning's Coefficient (n)**: This is an empirical coefficient that represents the resistance to flow offered by the boundary of the channel. It is primarily determined by the surface roughness of the canal bed and the side slopes. For example, a smooth concrete-lined canal has a much lower 'n' value than an earthen canal with vegetation or irregular rocks.
2. **Analysis of Options**:
- **Option a (Water temperature)**: Temperature affects viscosity and density, but it does not determine the roughness coefficient 'n'.
- **Option b (Roughness of the canal bed and side slopes)**: This is the primary factor. The physical texture, material, and alignment of the boundaries directly dictate the friction loss, which is what 'n' quantifies.
- **Option c (Water depth only)**: While depth affects the Hydraulic Radius (R), it does not define the coefficient 'n' itself (though in very shallow flows, relative roughness may play a role, it is not the primary factor for selecting the coefficient).
- **Option d (Shape of the canal)**: The shape affects the Hydraulic Radius (R), not the roughness coefficient (n). A trapezoidal concrete canal and a rectangular concrete canal would generally use the same 'n' value because the material (roughness) is the same.
Plane table surveying is best suited for-
A)
Large-scale geodetic surveys
B)
Highly accurate and precise measurements
C)
Quick and small-scale mapping
D)
Hydrographic surveys
Plane table surveying is a graphical method of surveying where field observations and plotting are done simultaneously.
1. Why Option 'c' is correct: Because the plotting is done in the field, there is no need for separate field notes or office-based plotting from notes. This makes the process very fast (quick). It is typically used for filling in details between primary control points or for mapping small areas where extreme precision is not the primary requirement.
2. Why Option 'a' is incorrect: Geodetic surveys account for the curvature of the earth and require extremely high precision over large areas. Plane table surveying assumes the earth is flat (plane), making it unsuitable for geodetic work.
3. Why Option 'b' is incorrect: Plane table surveying is generally less accurate than theodolite or total station surveying because it is subject to errors in plotting and sighting in the field.
4. Why Option 'd' is incorrect: Hydrographic surveys involve mapping water bodies (oceans, lakes, rivers) and require specialized equipment like echo sounders and sonar, which cannot be achieved using a plane table.
Which of the following irrigation methods is best suited for sandy soil?
A)
Sprinkler irrigation
B)
Drip irrigation
C)
Flood irrigation
D)
Furrow irrigation
Step-by-step reasoning:
1. Analysis of Sandy Soil: Sandy soils are characterized by high permeability and a high infiltration rate. Water percolates rapidly through the soil profile, leading to significant deep percolation losses if water is applied in large volumes over a long period.
2. Evaluating Flood and Furrow Irrigation: Both flood (c) and furrow (d) irrigation are surface irrigation methods. In sandy soils, water sinks vertically very quickly before it can move horizontally to cover the field. This results in extremely low irrigation efficiency and wasted water.
3. Evaluating Drip Irrigation: While drip irrigation (b) is highly efficient and can be used in sandy soils, it is primarily designed for high-value crops and specific root-zone targeting. However, for general field application in sandy soils, the primary challenge is the rapid downward movement of water.
4. Evaluating Sprinkler Irrigation: Sprinkler irrigation (a) is considered the best suited for sandy soils because it applies water in small, frequent doses (mimicking rainfall). This allows the water to be absorbed at a rate that matches the soil's infiltration capacity more effectively than surface flooding, reducing deep percolation losses and ensuring a more uniform distribution of moisture across the field.
Conclusion: Due to the high infiltration rate of sandy soils, sprinkler irrigation is the most technically and economically viable method among the choices provided.